Comparison of isometric ankle strength between females with and without patellofemoral pain syndrome

Ana Paula de Moura Campos Carvalho e Silva, PT, MSc Student1 Eduardo Magalhães, PT, Msc2 Flavio Fernandes Bryk, PT3 Thiago Yukio Fukuda, PT, PhD3

INTRODUCTION

Patellofemoral pain syndrome (PFPS) is the most common source of anterior knee pain in athletes and sedentary women, representing 20 to 40% of all individuals that are treated for knee injuries in orthopedic rehabilitation centers. Traditionally, the treatment of PFPS has focused on addressing structures about the knee joint, including quadriceps strengthening and hamstring and iliotibial flexibility, in order to decrease patellar maltracking and normalize patellofemoral contact. Recently, PFPS has been related to dynamic lower limb malalignment including excessive femoral medial rotation and adduction during eccentric daily activities, resulting in reduction of contact area in the patellofemoral joint. However the dynamic increase of tibiofemoral internal rotation could also decrease the patella to femur contact. Excessive or prolonged rearfoot eversion during gait could lead to a compensatory mechanism, causing an increase tibiofemoral internal rotation and consequently an excessive dynamic valgus. Baldon et al observed that greater rearfoot eversion (pronation of the foot) was associated with greater tibial internal rotation in subjects with PFPS. Based upon these biomechanical findings, many authors have recommended the use of foot orthoses to positively affect the alignment of the lower extremities, resulting in significant short and long-term satisfactory clinical outcomes. Thus, controlling excessive foot pronation may decrease the tibial and femoral internal rotation, thereby decreasing overload of the patellofemoral joint. The authors of this study believe that excessive foot pronation and calcaneal eversion during the midstance phase of gait could be the result of a muscular imbalance, related to dorsiflexor and invertor musculature weakness, especially the tibialis posterior muscle, which is assists in maintaining the medial longitudinal arch. With these concepts in mind, Barton et al17 and Powers et al18 suggested that increased foot pronation may be contributing factor in PFPS. Therefore, the aim of the current study was to compare the ankle dorsiflexor and invertor muscles strength, as well as rearfoot eversion and NDT in females with PFPS to a control group of females of similar demographics without PFPS. The authors hypothesized that when compared to a pain-free control group, females with PFPS would exhibit decreased ankle strength and increased rearfoot eversion and navicular drop. This study may help in the clinical understanding of the relationship between ankle muscle strength and PFPS. METHODS Subjects Twenty females between the ages of 20 and 40 years (mean 23.0 ± 3.0 years; height 162.0 ± 7.0 cm; body mass 56.8 ± 10.0 kg) diagnosed with unilateral (n=7) or bilateral (n=13) PFPS were recruited from the Physical Therapy sector of the Irmandade Santa Casa de Misericordia de São Paulo Hospital. The inclusion criteria for the PFPS group were the same criteria described by Thomee et al.19 Pain during at least 3 of the following activities: squatting, climbing up or down stairs, kneeling, sitting for long periods, or when performing resisted isometric knee extension at 60 degrees of knee flexion; insidious onset of symptoms unrelated to trauma and persistence for at least 4 weeks; and pain on palpation of the medial or lateral facet of the patella. Twenty control females (mean ± SD age, 24.0 ± 3.0 years; height, 163.0 ± 6.0 cm; body mass, 61.9 ± 10 kg), who presented with upper extremity tendinopathies and without lower extremity involvement were recruited from the same sector to serve as the control group. The exclusion criteria for both groups included the presence of any other associated knee conditions including patellar instability, patellofemoral joint dysplasia, meniscal or ligament injuries, tendon or cartilage injury, a decrease of range of motion in dorsiflexion, and a history of inversion injuries within the last 2 years. Subjects were also excluded if they had any neurological diseases, previous surgery of the lower limbs, lumbar pain, sacroiliac joint pain, rheumatoid arthritis, or were pregnant. It is important to highlight that all females included in both groups were active, but not competitive athletes.20 Before taking part in this study, the subjects were informed of the procedures and signed an informed consent approved by the Ethics Committee on Research of the ISCMSP.

Procedures

A senior physical therapist determined subject participation in both groups based on the inclusion and exclusion criteria. The subjects completed the Anterior Knee Pain Scale (AKPS) and a verbal numeric pain rating scale (NPRS). Another evaluator, who was blinded to group assignment, measured all subjects for the NDT and rearfoot eversion bilaterally, followed by ankle manual muscle strength assessment. The data for pain, function, duration of symptoms, ankle strength, rearfoot eversion and NDT for the PFPS group were obtained from the affected limb of the subjects with unilateral PFPS and the most affected limb of subjects with bilateral PFPS. In relation to control, the authors used the mean value of both sides for data analysis.

Functional

Evaluation The Anterior Knee Pain Scale (AKPS) was used to measure self-reported function. The AKPS contains 13 items, each based on a 6-point scale, where the highest score represents no difficulty when performing the task and the lowest score represents complete inability to perform the activity. The maximum score is 100 and indicates that there is no deficiency; a score below 70 suggests moderate pain and disability. This questionnaire is reliable and valid, and has been widely used for patients with PFPS. Pain was measured with an verbal 11-point Numeric Pain Rating Scale (NPRS) where 0 corresponded to no pain and 10 corresponded to “worst imaginable pain”.

Foot evaluation

Foot pronation was assessed using the NDT. This test measures the difference in millimeters of the navicular tuberosity from the ground between a relaxed, weight bearing position, and a position of “imposed” subtalar neutral in standing. Initially, the subjects were placed on a rigid surface and placed in a neutral subtalar joint position, and the navicular height was measured. Next, the subjects were asked to relax and stand in their preferred posture, and the measurement was repeated. In the authors’ laboratory the reliability for NDT, was 0.80 (ICC2,1) and SEM 0.20mm. Then, the therapist passively positioned the calcaneus in maximum eversion and motion was measured with a goniometer, and named rearfoot eversion. The reliability for rearfoot eversion in the authors’ laboratory28 was 0.82 (ICC2,1) and SEM 0.75 degrees.

Isometric

Muscle Strength A Nicholas hand-held dynamometer (Lafayette Instrument Company, Lafayette, IN) was used to measure isometric strength during a “make test” of the ankle dorsiflexors and invertors. This instrument is widely used clinically to measure muscle isometric strength. The dorsiflexor ankle strength was assessed while the subject lying in a supine position. The evaluated limb was positioned with the extended knee and the ankle joint remained in an unrestrained and neutral position. The dynamometer was placed against the dorsal surface of the foot near the metatarsal heads (FIGURE 1-A). In the authors’ laboratory, reliability for isometric muscle strength measurement of the dorsiflexors was 0.95 (ICC2,1) and SEM of 1.00 kg. The invertor muscles were evaluated with the subject in the same position and the dynamometer was placed on the medial border of the foot at the shaft midpoint of the first metatarsal. In the authors’ laboratory, reliability for isometric muscle strength measurement of the invertors was 0.77 (ICC2,1) and SEM 1.97 kg. During isometric strength testing, two submaximal trials were allowed for the subject to become familiar with each test position. This was followed by two trials with the subject providing maximal isometric effort for each muscle group, using consistent verbal encouragement. The interval between the second submaximal contraction and the first maximum isometFigure 1. Strength measurement for the dorsifl exor (A) and invertor (B) musculature IJSPT ric contraction was 10 seconds. The duration of each maximum isometric contraction was standardized at 5 seconds, with a rest time of 30 seconds between maximum isometric contractions. Testing order for the muscle groups was randomized. After evaluation of a muscle group, a standard 1-minute rest period was given before evaluating the other muscle group. When the examiner observed any compensation or combined movements during a test, the values were disregarded and the test was repeated after 20 seconds of rest. The mean values of the two maximal effort trials (one mean for each of the tested muscle groups) were utilized for data analysis.

Data Reduction

Isometric strength measurements, measured in kilograms (Kg), were normalized to body mass, also reported in Kg by using the following formula: (Kg strength / Kg body weight) x 100.29,33

Data Analysis

Normality was assessed using Shapiro-Wilk test. Independent t-test were used to measure and compare demographics data, NPRS scores, AKPS scores, normalized dorsiflexor and invertor isometric strength; and the Mann-Whitney test was used to compare the NDT and rearfoot eversion measurements between groups. SigmaStat 3.5 was used for data analysis and the alpha level was set at 0.05.

RESULTS

Demographic data for the PFPS group and the control group are provided in Table 1. The PFPS and the control group were not statistically different in terms of age, weight, and height (p>0.05). Dorsiflexor and invertor muscle strength, NDT measurements, and the rearfoot eversion measurements of both groups are presented in Table 2. There were no statistically significant differences in normalized dorsiflexor (p=0.80) and invertor (p=0.60) muscle strength between the PFPS group and the control group. Moreover, the NDT and the rearfoot eversion measurements were not significantly different (p = 0.40 and p = 0.30, respectively) between groups.

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DISCUSSION

The purpose of this study was to compare ankle dorsiflexion and inversion isometric strength, measures of foot pronation and rearfoot eversion between sedentary women with and without PFPS. There were no differences between groups, thus rejecting the authors’ initial hypothesis. Faulty mechanics at the hip have been correlated with PFPS, particularly excessive femoral adduction and internal rotational. Strengthening of the hip abductor and external rotators is commonly recommended in the management of this disorder. Similarly, faulty mechanics of the foot and ankle distally have been implicated in PFPS including excessive foot pronation and internal tibial rotation resulting in medial femoral rotation and increased patellofemoral stress. It is not surprising that the subjects in this study did not differ in ankle strength from the control group. Piazza stated that when the foot is in a pronated position, the anterior tibialis would present an active restraint to pronation, thereby losing it is function as a rearfoot invertor. Then, one possible reason for the lack of differences between groups in the current study is the fact that the invertor muscles did not lose their function, since the subjects and controls did not differ in relation to foot pronation (as measured using the NDT) or rearfoot eversion. In contrast to the current findings, Barton et al39 inferred that subjects with PFPS would present with greater navicular drop measurement when compared to controls. However, even if a difference had been found in NDT between groups, maybe that would not interfere with isometric strength of the chosen ankle muscles, since Snook did not find a positive correlation between excessive pronation and ankle muscle weakness in healthy population. Some authors have reported that the foot remains pronated when it should already be supinated during closed chain activities such as walking, running and other functional activities in subjects with PFPS, resulting in excessive internal tibial rotation. So, this suggests a possible delay in the activation time of rearfoot inversion during these activities.11,12,41 Many authors have surmised that this inversion occurs due to muscular delayed activation or pre vious muscle fatigue, instead of actual ankle muscle weakness, thus subjects with PFPS may not present with weakness of the inverters and dorsiflexors. Other factors that could be related would be the difference between available ankle range of motion (ROM) and pronation velocity during closed chain activities in subjects with and without PFPS, however these two constructs were not studied in the current research. Another contributor to PFPS may be excessive hip adduction and internal rotation. Fukuda et al35 and Mascal et al34 observed that after a hip abductor and external rotator strengthening program, subjects with PFPS showed significant clinical improvement in terms of function and pain relief. Corroborating these data, some authors demonstrated that an associated 6-week strengthening program focusing on hip abductor and external rotator strengthening, can control the dynamic tibial internal rotation during jogging, thus decreasing the eversion amplitude and the inversion rearfoot moment.42 Some limitations of this study include the method of muscle strength evaluation, due to lack of other evidence regarding ankle muscle isometric dynamometry. Also, handheld dynamometry testing is both examiner- and test-position dependent. However, a pilot study was previously performed by the authors in order to establish reliability, and demonstrated satisfactory to excellent reliability. It is important to highlight that other options for assessment methods of rearfoot eversion could have been used, such as plain film radiographs or motion analysis during a dynamic gait task. However, we chose the NDT and eversion range of motion measures because they are widely used methods in the clinical practice with good to excellent interrater and intrarater reliability for patients with patellofemoral pain syndrome. To the authors’ knowledge, this is the first study focusing on the measurement of isometric ankle muscle strength of the PFPS population. Therefore, future studies are needed to better understand the relationship between such variables as ankle muscle strength and patellofemoral contact area, as well as the possible influence of the timing of muscle activation using electromyography and kinematic assessments of changes during functional activities. Finally, the main clinical implication of this study is that there were no statistical differences in the ankle muscle strength measurements, and measures of foot pronation and rearfoot eversion between PFPS and control groups.

CONCLUSION

The results of this study indicate that there is no difference in nomalized isometric ankle strength in women with PFPS and those without. When compared to a matched control group, neither the NDT nor the rearfoot eversion measurements were statistically significantly different.

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Stabilization exercise compared to general exercises or manual therapy for the management of low back pain: A systematic review and meta-analysis

Mansueto Gomes-Neto, Jordana Moura Lopes, Cristiano Sena Conceição, Anderson Araujo, Alécio Brasileiro e, Camila Sousa, Vitor Oliveira Carvalho e Fabio Luciano Arcanjo.

1. Background: Low back pain (LBP) is a multifactorial disorder with a high prevalence; most people experience back pain at some point in their life and it has a significant impact on individuals, their families, and the healthcare systems. This disorder causes disability, participation restriction, a career burden, the use of health-care resources, and a financial burden. In addition to medical treatment, musculoskeletal physiotherapy (exercise therapy and manual therapy) is the most common method of conservative intervention for LBP (Amit, Manish, & Taruna, 2013; Hoy, Brooks, Blyth, & Buchbinder, 2010; Smith et al., 2014). The European Guidelines for Management of Chronic Non-Specific Low Back Pain (Airaksinen et al., 2006) recommend supervised exercise therapy as the first-line treatment. Stabilization exercise programs have become widely used for low back rehabilitation because of its effectiveness in some aspects related to pain and disability (Ferreira, Ferreira, Maher, Herbert, & Refshauge, 2006; Liddle, David Baxter, & Gracey, 2009). Stabilization exercise are exercise interventions that aim to improve function of specific trunk muscles thought to control inter-segmental movement of the spine and enable the patient to regain control and coordination of the spine and pelvis using principles of motor learning such as segmentation and simplification (Hodges and Richardson, 1996; Richardson, Jull, Hides, & Hodges, 1999). Although stabilization exercises have become the major focus in spinal rehabilitation, as well as in prophylactic care, the therapeutic evidence using pain and disability control variables as outcomes remains controversial. Most therapeutic studies have compared stabilization exercise, general exercise, and manual therapy. Systematic reviews to date that have evaluated the effectiveness of exercise therapies have concluded that there is no evidence to support the superiority of one form of exercise over another (Ferreira et al., 2006; Macedo et al., 2010). In a recent review, Wang et al. (Wang et al., 2012) showed that stability exercise is more effective for decreasing pain than general exercise, and it may improve physical function in patients with chronic LBP. However, the efficacy of stability exercise was not compared with manual therapy. After reviews on this topic were published (Ferreira et al., 2006; Macedo et al., 2010; Wang et al., 2012), new randomized controlled trials (RCTs) have been released (Amit et al., 2013; Inani and Selkar, 2013; Macedo et al., 2012; Sung, 2013). The Cochrane Collaboration recommends that systematic reviews be updated biannually (Higgins and Green, 2006). Moreover, as far as we know, no meta-analysis has been performed on studies comparing segmental stabilization exercise with manual therapy. The meta-analysis technique minimizes subjectivity by standardizing treatment effects of relevant studies into effect sizes (ESs), pooling, and analyzing data to draw conclusions. The aim of this systematic review with meta-analysis was to analyze published RCTs that investigated the efficacy of stabilization exercises versus general exercises or manual therapy in patients with LBP.

2. Methods: This review was planned and performed in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines (Moher et al., 2009).

2.1. Eligibility criteria: This systematic review included all RCTs that investigated the efficacy of stabilization exercises in patients with non-specific LBP. Studies that compared a stabilization exercises group with a general exercises group or a stabilization exercises group with a manual therapy group were included. Studies were considered for inclusion regardless of publication status, language, or size. Trials that enrolled patients with chronic non-specific LBP were included in this meta-analysis. For this study was considered the chronic nonspecific LBP as low back pain (>3 months’ duration) without leg pain. The studies that enrolled patients with acute LBP in association with neurologic diseases were excluded from this systematic review. The main outcomes of interest were pain (assessed using visual analog scale, numerical rating scale, or any other instrument or scale) with scores ranging from 0 to 10, disability, and function assessed by any questionnaire. To be eligible, the RCTs should have randomized patients with chronic LBP to at least one group of stabilization exercises. For this review, stabilization exercises was considered as prescribed exercises aimed at improving function of specific trunk muscles that control inter-segmental movement of the spine, including the transversus abdominis, multifidus, diaphragm, and pelvic floor muscles (Hodges and Richardson, 1996; Richardson et al., 1999). General exercise were prescribed exercises that included strengthening and/or stretching exercises for the main muscle groups of the body as well as exercises for cardiovascular fitness. Manual therapy comprised physiotherapy based on manual techniques (joint mobilization or manipulation techniques).

2.2. Search methods for identification of studies: We searched for studies on MEDLINE, LILACS, EMBASE, SciELO, Cumulative Index to Nursing and Allied Health (CINAHL), PEDro, and the Cochrane Library, up to November 2014, without language restrictions. A standard protocol for this search was developed and whenever possible, a controlled vocabulary was used (Mesh terms for MEDLINE and Cochrane; EMTREE for EMBASE). Keywords and their synonyms were used to sensitize the search. For identification of RCTs in PUBMED, the optimally sensitive strategy developed for the Cochrane Collaboration was used (Higgins and Green, 2006). For identification of RCTs in EMBASE, a search strategy using similar terms was adopted. In the search strategy, there were four groups of keywords: study design, participants, interventions, and outcome measures. We analyzed the reference lists of all eligible articles in order to detect other potentially eligible studies. For ongoing studies or when any data was to be confirmed or additional information was needed, the authors were contacted by e-mail. The previously described search strategy was used to obtain titles and abstracts of studies that were relevant for this review. Each identified abstract was independently evaluated by two authors. If at least one of the authors considered one reference eligible, the full text was obtained for complete assessment. Two reviewers independently assessed the full text of selected articles to verify if they met the criteria for inclusion or exclusion. In case of any disagreement, the authors discussed the reasons for their decisions and a consensus was reached. Two authors, independently blinded, extracted descriptive and outcome data from the included studies using a standardized form developed by the authors and adapted from the Cochrane Collaboration’s (Higgins and Green, 2006) model for data extraction. We considered: 1) aspects of the study population, such as the average age and sex; 2) aspects of the intervention performed (sample size, type of stabilization exercise performed, presence of supervision, frequency, and duration of each session); 3) follow-up (if the patients included were analyzed); 4) loss to follow-up (if there was a loss in the sample); 5) outcome measures; and 6) presented results. Another author resolved disagreements. Any additional information required from the original author was requested by e-mail. The risk of bias of included studies was assessed independently by two authors using The Cochrane Collaboration’s “Risk of bias” tool (Higgins and Green, 2006). The following criteria were assessed: Random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, intention-to-treat analysis, and completeness of follow-up. The quality of evidence was independently scored by two researchers based on the PEDro scale (Olivo et al., 2008) that consisted of 11 items based on a Delphi list (Verhagen et al., 1998). The PEDro scale is a useful tool for assessing the quality of physical therapy and rehabilitation trials (Olivo et al., 2008). One item on the PEDro scale (eligibility criteria) is related to external validity and is generally not used to calculate the method score, leaving a score range of 0e10 (Maher, Sherrington, Herbert, Moseley, & Elkins, 2003).

2.3. Statistical assessment: Pooled-effect estimates were obtained by comparing the least square mean percentage change from the baseline to the study end for each group, and were expressed as the weighted mean difference between groups. Calculations were performed using a random-effects model. Two comparisons were made: stabilization exercises group versus general exercises group and stabilization exercises group versus manual therapy group. An a value of 0.05 was considered significant. Statistical heterogeneity of the treatment effect among studies was assessed using Cochran’s Q-test and the inconsistency I (Hoy et al., 2010) test, in which values between 25% and 50% were considered indicative of moderate heterogeneity, and values > 50% were considered indicative of high heterogeneity (Higgins, Thompson, Deeks, & Altman, 2003). All analyses were conducted using Review Manager Version 5.0 (Cochrane Collaboration). (CollaborationAvailab).

3. Results: The initial search led to the identification of 653 abstracts, from which 24 studies were considered as potentially relevant and were retrieved for detailed analysis. After complete reading of 24 articles, 13 were excluded. Finally, 11 papers (Akbari, Khorashadizadeh, & Abdi, 2008; Amit et al., 2013; Ferreira et al., 2007; França, Burke, Hanada, & Marques, 2010, 2012; Goldby, Moore, & Doust, 2006; Inani and Selkar, 2013; Macedo et al., 2012; Rasmussen-Barr, Nilsson-Wikmar, & Arvidsson, 2003; Sung, 2013; Unsgaard-Tøndel, Fladmark, Salvesen, & Vasseljen, 2010) met the eligibility criteria. Fig. 1 shows the PRISMA flow diagram of studies for this review. Each of the papers was scored using the PEDro scale. Table 1 presents the results of individual assessment by the PEDro scale. The final sample ranged from 30 to 172 participants, and the mean age ranged from 59 to 67 years. All studies analyzed in this review included outpatients with documented LBP. The parameters used in the application of stabilization exercises have been reported, and all studies described the progressive nature of the programs. The duration of stabilization exercises programs ranged from 4 to 12 weeks. The duration of sessions varied from 20 to 60 min in the studies. The frequency of sessions ranged from one to three times per week. Table 2 summarizes the characteristics of included studies.

3.1. Pain intensity: In total, eight trials assessed pain intensity (Akbari et al., 2008; Amit et al., 2013; Ferreira et al., 2007; França et al., 2010; Goldby et al., 2006; Macedo et al., 2012; Rasmussen-Barr et al., 2003; Sung, 2013). The meta-analyses showed (Fig. 2) a significant improvement in pain of 1.03 (95% CI: 1.79 to 0.27, N ¼ 603) for participants in the stabilization exercises group compared to the general exercises group. Three studies compared stabilization exercise to manual therapy (Ferreira et al., 2007; Goldby et al., 2006; Rasmussen-Barr et al., 2003). A non-significant difference in pain of 0.38 (95% CI: 0.98 to 0.22, N ¼ 358; Fig. 3) was noted for participants in the stabilization exercises group compared to the manual therapy group. Age mean.

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3.2. Disability: Seven trials assessed disability (Ferreira et al., 2007; França et al., 2010, 2012; Inani and Selkar, 2013; Macedo et al., 2012; Sung, 2013; Unsgaard-Tøndel et al., 2010). Five of these studies measured disability using the Oswestry Disability Index (França et al., 2010, 2012; Inani and Selkar, 2013; Sung, 2013; Unsgaard- Tøndel et al., 2010), and two assessed disability using the Roland-Morris Disability Questionnaire (Ferreira et al., 2007; Macedo et al., 2012). In four individual trials, significant improvements were found in the stabilization exercises group compared to the general exercises group as measured by the Oswestry Disability Index. The meta-analyses showed a significant improvement in disability of 5.41 (95% CI: 8.34 to 2.49, N ¼ 209; Fig. 4) for participants in the stabilization exercises group compared to the general exercises group. As assessed using the Roland-Morris Disability Questionnaire, the non-significant difference in disability of 0.75 (95% CI: 2.26 to 0.75, N ¼ 310; Fig. 5) was noted for participants in the stabilization exercises group compared to the general exercises group. Three studies compared stabilization exercise to manual therapy (Ferreira et al., 2007; Goldby et al., 2006; Rasmussen-Barr et al., 2003). A non-significant difference in disability of 0.17 (95% CI: 0.38 to 0.03, N ¼ 358) was found for participants in the stabilization exercises group compared with manual therapy (Ferreira et al., 2007; Goldby et al., 2006; Rasmussen-Barr et al., 2003). (Fig. 6) Owing to the differences between instruments used to measure disability (stabilization exercises group versus manual therapy group), a meta-analysis was performed using the standardized mean difference. All studies included patients of both genders, but there was an overall predominance of female. The mean age ranged from 38 (Rasmussen-Barr et al., 2003) to 53 (Ferreira et al., 2007) years. All studies analyzed in this review included outpatients with documented chronic nonspecific LBP (pain duration > 12 weeks). The parameters used in the application of manual therapy have been reported. The duration of manual therapy programs ranged from 8 (Ferreira et al., 2007) to 12 (Goldby et al., 2006; Rasmussen-Barr et al., 2003) weeks. The duration of sessions varied from 45 (Rasmussen-Barr et al., 2003) to 60 (Ferreira et al., 2007; Goldby et al., 2006) min in the studies. The frequency of sessions ranged from one (Rasmussen-Barr et al., 2003) to two (Ferreira et al., 2007) times per week. Table 2 summarizes the other characteristics of included studies.

3.3. Function: Two trials assessed function using the Patient-Specific Functional Scale (Macedo et al., 2012; Verhagen et al., 1998). The nonsignificant difference in function of 0.01 (95% CI: 1.18 to 1.21, N ¼ 310) (Fig. 7); was noted for participants in the stabilization exercises group compared with the general exercises group.

3.4. Risk of bias in the included studies: The studies did not have enough detail for assessing the potential risk of bias. Details regarding the generation and concealment of the random allocation sequence were poorly reported. Six studies presented objective evidence of the random allocation characteristics. The studies presented objective evidence of balance in baseline characteristics. Only three studies stated that the measurements were blinded.

4. Discussion: In the present systematic review, a meta-analysis of 8 studies indicated that stabilization exercises were more effective than general exercises in reducing pain. Five studies demonstrated a significant improvement in disability between patients treated with stabilization exercises compared with those treated with general exercises. Moreover, the meta-analysis of three studies demonstrated that stabilization exercises were as efficacious as manual therapy in decreasing pain and disability. In our meta-analysis the mean of pain in the analyzed studies was 6.01 at baseline, being 2.1 at the end of the stabilization exercises on a 0e10 pain scale. Specifically, the WMD in pain was 1.03 favoring stabilization exercises, what represents an improvement of 39% in pain. Considering pain, for patients with subacute or chronic LBP, the minimally clinically important change for pain on a visual analog scale (0e10) should at least be 20%. If a numerical rating scale (0e10) is used it seems reasonable to suggest that the minimally clinically important change should at least be 25% for patients with chronic LBP (Ostelo and de Vet, 2005). The results of this review are consistent with the findings of a previous systematic review (Ferreira et al., 2006; Macedo et al., 2010) on the effects of stabilization exercise on nonspecific LBP. Our meta-analysis indicated that stabilization exercise can be more effective than general exercise in improving pain and disability in the short term, but it was not superior to manual therapy. In another systematic review by Pereira et al. (Pereira et al., 2012), stabilization exercise and Pilates offered no significant improvement in functionality. Previously, two other meta-analyses (Rackwitz et al., 2006; Wang et al., 2012) reported that specific stabilization exercises was better than ordinary medical care provided by a general practitioner to reduce pain over the short and intermediate terms. However, in a recent meta-analysis, Macedo et al. (Macedo, Maher, Latimer, & McAuley, 2009) demonstrated that stabilization exercises were superior to minimal intervention, but not more effective than manual therapy. Macedo and coworkers’ results are in agreement with those of our meta-analysis (Macedo et al., 2009). Contrary to our results, the meta-analysis by Macedo et al. (Macedo et al., 2009) also demonstrated that stabilization exercises were not more effective than other forms of exercise.

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This disagreement can be explained by several different approaches currently in use for stabilization exercise to treat LBP. A standard protocol and definition for stabilization exercises is yet to be established. Therefore, there is a wide variation among studies in how the exercises were named and implemented (Lewis et al., 2005). Nevertheless, multiple studies have shown that not all subjects with LBP benefit equally from stabilization exercise (Hicks, Fritz, Delitto, & McGill, 2005). A recent review of studies has shown that therapy that is specifically directed at well-defined subgroups leads to improved effectiveness of interventions (Karayannis, Jull, & Hodges, 2012). The identification of predictive factors in patients with LBP should allow the prescription of the most appropriate treatment intervention, maximizing the likelihood of a favorable clinical outcome (Brennan et al., 2006; Fersum et al., 2010). In the present review, the included studies did not report concealment allocation or randomization in an appropriate manner. Thus, the effectiveness of stabilization exercises may be even lower in studies with proper randomization and concealment allocation. Our meta-analysis showed that stabilization exercise was as efficient as manual therapy for improving in pain and disability. However, the total number of patients involved in the meta-analysis was too small to identify relatively small disparities between the effects of stabilization exercise and manual therapy. It is difficult to make a definitive and pragmatic recommendation regarding stabilization exercise for patients with LBP. There was a variation in the duration of exercise programs, progression criteria, muscle activation, and type of feedback used during the interventions. However, with the exception of the study of Ferreira et al. (Ferreira et al., 2007) did not inform which protocol was used for stabilization, the protocol used in the studies were based on the protocol proposed by Richardson & Hodges (Hodges and Richardson, 1996; Richardson et al., 1999). Caution is warranted when interpreting the present results given the significant heterogeneity found in primary analyses. The use of different instruments for assessment and intervention programs (session time and duration of intervention) can compromise the comparisons. The studies used different scales and time periods to measure pain intensity (e.g., pain in last 24 h, pain in the last months) and disability (e.g. the Roland Morris Disability Index and the Oswestry Disability Index) and the duration of intervention and the time points of follow-up were different. Despite the differences in frequency and duration, stabilization exercise using the principles proposed by Richardson & Hodges (Hodges and Richardson, 1996; Richardson et al., 1999). were superior to general exercise that prioritizes exercise of superficial muscles. One of the limitations of this review was that the findings were based on relatively low quality data that led to a high risk of bias. Additional research is required to ascertain the positive effects of stabilization exercise over time and to determine their essential attributes, such as mode, intensity, frequency, duration, and timing. New RCTs testing different stabilization exercise for LBP should be conducted to determine the optimal treatment approach. Additionally, it will be important to match exercise prescription to clinical/treatment characteristics of a patient subgroup or individual patient.

5. Conclusion: Stabilization exercises and/or manual therapy can be encouraged as part of musculoskeletal rehabilitation for patients with LBP. However, the best prescription program, needs to be determined by new RCTs.

The initial effects of a Mulligan’s mobilization with movement technique on dorsiflexion and pain in subacute ankle sprains

Natalie Collins, Pamela Teys, Bill Vicenzino*
Department of Physiotherapy, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia
Received 17 December 2002; received in revised form 25 July 2003; accepted 21 August 2003

Introduction

The lateral ligament complex of the ankle, described as the body’s ‘‘most frequently injured single structure’’ (Garrick, 1977), is mechanically vulnerable to sprain injury. At extremes of plantarflexion and inversion, influenced by the shorter medial aspect of the ankle mortise, the relatively weak anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) are prone to varying grades of rupture, often via minimal force (Hockenbury and Sammarco, 2001). Immediate inflammatory processes produce acute anterolateral pain and oedema, with avoidance of movement and weight bearing (Wolfe et al., 2001). Subsequent losses of joint range, particularly dorsiflexion, and muscle strength results in significant gait dysfunction. Recent data from our laboratory highlights the presence of a dorsiflexion deficit not only in the acute stage, but also in the subacute stage (Yang and Vicenzino, 2002). Early physiotherapy intervention consists of rest, ice, compression, elevation (RICE) and electrotherapy modalities to control inflammation, as well as manipulative therapy and therapeutic exercise techniques to address impairments of movement and strength (Wolfe et al., 2001; Hockenbury and Sammarco, 2001). Green et al. (2001) investigated the impact of combining nonweight-bearing talocrural anteroposterior (AP) passive mobilisations, believed to restore dorsiflexion range, with the RICE protocol in the treatment of acute ankle sprains. The experimental group ðn ¼ 19Þ demonstrated a more rapid improvement in pain-free dorsiflexion and function than the control group ðn ¼ 19Þ who were treated solely with RICE. This provides important evidence substantiating the role of passive joint mobilizations in an acutely injured population. The mobilization with movement (MWM) treatment approach for improving dorsiflexion post-ankle sprain combines a relative posteroanterior glide of the tibia on talus (or a relative anteroposterior glide of the talus on the tibia) with active dorsiflexion movements, preferentially in weight bearing (Mulligan, 1999). Claims of rapid restoration of pain-free movement are associated with MWM techniques generally (Mulligan, 1993, 1999; Exelby, 1996). Through examination of the effects of MWM on ankle dorsiflexion in asymptomatic mildly restricted ankle joints, Vicenzino et al. (2001) found that both the weight bearing and non-weightbearing variations of the dorsiflexion MWM technique produced significant gains in dorsiflexion range. However, weight-bearing treatment techniques are widely believed to be superior to non-weight-bearing techniques, as they replicate aspects of functional activities (Mulligan, 1999). Acute ankle sprains, whilst having marked reduction in dorsiflexion range of motion, are frequently painful in full weight bearing, and weightbearing techniques are not clinically indicated. The subacute ankle sprain is characterized by significant residual deficits in dorsiflexion (Yang and Vicenzino, 2002) and the capacity to fully weight bear, making it a good model on which to study the initial effects of weight-bearing MWM on dorsiflexion. The mechanism of action of manipulative therapy has been the focus of several reports in recent times, however spinal manipulative therapy appears to be the common subject of research. A synopsis of current evidence for the initial mechanism of action of manipulative therapy indicates in part a neurophysiological basis (Vicenzino et al., 1996, 1998, 2000). Manipulative therapy treatment techniques studied have exhibited non-opioid hypoalgesia to mechanical but not thermal pain stimuli (Vicenzino et al., 1995, 1998). The primary objective of this study was to test the hypothesis that application of Mulligan’s MWM technique for talocrural dorsiflexion to subacute lateral ankle sprains produces an initial dorsiflexion gain, and simultaneously produces a mechanical but not thermal hypoalgesia.

Methods

The double-blind randomized controlled trial incorporated repeated measures into a cross over design, in which each participant served as their own control.

Participants: Sixteen participants, eight males and eight females aged 18–50 (average 28.25 years and standard deviation 9.33 years), were recruited through the University Physiotherapy Clinic, local physiotherapy practices and sporting clubs, and University advertising. The primary criterion for inclusion was a grade II ankle lateral ligament sprain that was sustained on average 40 days (724 days standard deviation) prior to testing. We defined this sprain as ‘‘an incomplete tear of the ligament with mild laxity and instability (and) slight reduction in functiony’’ (Safran et al., 1999); A minimum pain-free dorsiflexion asymmetry of 10mm on weight-bearing measure (Vicenzino et al., 2001), anterolateral ankle tenderness, and full pain free weightbearing capacity were also required. Acute ankle sprains were excluded due to the potential for exacerbation of pain with repeated testing on the outcome measures. Exclusion also occurred if fracture or intra-articular ankle effusion were clinically detectable, or if there was a recent history of other lower limb or lumbar spine conditions. Physiotherapists and physiotherapy students were excluded to remove a potential source of bias from the participants. Ethical clearance was obtained from the relevant Institution Review Board for ethics at the University of Queensland, and all participants provided informed consent.

Outcome measures
Dorsiflexion: Weight-bearing dorsiflexion (DF), found to have excellent inter- and intra-rater reliability (Bennel et al., 1998), was measured using the knee-to-wall principle. The participant stood in front of a wall, with the test foot’s second toe and midline of the heel and knee maintained in a plane perpendicular to the wall. The participant slowly lunged forward into talocrural dorsiflexion until the knee contacted the wall, and progressively moved the foot back to the point where the knee could just touch the wall with the heel sustained on the ground. This represented end of range dorsiflexion, and the distance between the wall and second toe was measured in millimetres using a tape measure. The examiner ensured maintenance of heel contact via verbal instructions and manual contact with the calcaneum. Vicenzino et al. (2001) found this measure to be more sensitive in detecting treatment effects than an angular weight-bearing measure and a non-weight-bearing measure.

Pain: Quantitative measures of pain were obtained via pressure and thermal pain threshold. Pressure algometry, which has demonstrated reliability (Pontinen, 1988), was used to measure pressure pain threshold (PPT) at three lower limb sites:over the proximal third of the tibialis anterior muscle belly; (2) directly distal to the lateral malleolus over the CFL; directly anterior to the lateral malleolus over the ATFL. A digital pressure algometer (Somedic AB, Farsta, Sweden) was used to measure the pressure applied to the test site by a rubbertipped probe (area 1 cm2), which was positioned perpendicular to the skin. The pressure was applied at a rate of 40 kPa/s. Activation of a button by the participant at the precise moment that the pressure sensation changed to one of pain and pressure, signalled cessation of pressure application, and froze the measurement onscreen for manual recording. The Thermotest System (Somedic AB, Farsta, Sweden) measured hot and cold thermal pain threshold (TPT). A rectangular contact thermode was manually positioned over two sites: (i) the proximal third of the tibialis anterior muscle belly, and (ii) over the ATFL, extending from the anteroinferior border of the lateral malleolus toward the toes at an angle that allowed maximal contact with the foot contours. The hot or cold stimuli were increased at a rate of 1ºC/s from a baseline of 30ºC. Participants pressed a button at the precise moment that the thermal sensation changed to one of pain and heat for heat pain threshold, and one of pain and cold for cold pain threshold. At this point, stimulation ceased and the temperature reached was manually recorded. Automatic cut-off points of 52ºC and 2.5ºC were adopted to ensure safe stimulus application.

Treatment conditions: Three treatment conditions, consisting of MWM for dorsiflexion, placebo and a no-treatment control, were studied. During the treatment condition, the dorsiflexion MWM technique was performed on the symptomatic talocrural joint, as described by Mulligan (1999). With the participant in relaxed stance on a bench, a nonelastic seatbelt was placed around the distal tibia and fibula and the therapist’s pelvis, with foam cushioning the Achilles tendon. A backward translation by the therapist imparted tension on the seatbelt and a posteroanterior tibial glide, while the talus and forefoot were fixated with the webspace of one hand close to the anterior joint line. The other hand was positioned anteriorly over the proximal tibia and fibula to direct the knee over the second and third toes to maintain a consistent alignment of the distal leg and foot. The glide was sustained during slow active dorsiflexion to end of pain-free range, with the seatbelt kept perpendicular to the long axis of the tibia throughout movement, and released after return to the starting position. Three sets of 10 repetitions were applied, with one minute between sets (Exelby, 1996). Pain experienced during treatment resulted in immediate cessation of the technique and exclusion from the study. The placebo condition replicated the treatment condition, with the following exceptions. The seatbelt was placed over the calcaneum, and only minimal tension imparted to take up the slack. One hand remained on the proximal tibia and fibula, however the other hand was positioned across the metatarsal bases. Instructions were given to produce a small inner range dorsiflexion while the seatbelt was maintained perpendicular to the tibia. An identical number of repetitions, sets and interval period were used. In the control condition, the participant assumed the same relaxed stance position as for treatment and placebo, and maintained this for five minutes. No manual contact occurred between the therapist and participant.

Procedure: A preliminary session, during which a clinical examination and the three outcome measures were performed on both ankles, was conducted initially to determine the participant’s suitability for inclusion. This session also served to familiarize participants with testing procedures. Suitable participants returned for three testing sessions within one week of the initial appointment. These were scheduled at similar times of the day to prevent diurnal variations in joint range and pain, and allow a 24-h interval for wash-out of any treatment effects. Testing was conducted in an environment-controlled laboratory, with constant temperature and humidity. Each testing session began with the asymptomatic then symptomatic ankles undergoing each of the three outcome measures. With the participant in side lying, a splint was applied to the testing ankle to maintain a standardized 10 of plantarflexion. PPT and TPT measures were then conducted in an order randomized by the toss of a coin, followed by weight-bearing dorsiflexion. Three repetitions of each measure were taken. The examiner then left the laboratory while the therapist then entered and applied one of the treatment conditions (MWM, placebo, control) to the symptomatic ankle. Following treatment, outcome measures were repeated on the symptomatic ankle by the examiner to evaluate the effect of treatment. This  procedure facilitated blinding of the examiner. The participant was unaware of the aim of the study and which treatment condition was under investigation. Over the 3 days of involvement in the primary study, each participant experienced all three treatment conditions in a randomised order as determined by the roll of a dice by the therapist.

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Reliability

Acceptable intrarater reliability was determined through analysis of pre-treatment data from the three testing sessions. The intraclass correlation coefficient (ICC) and standard error of measurement (SEM) data for the pain measures are presented in Table 1. The ICC and SEM for the dorsiflexion measure were 0.99 and 3.50 mm, respectively. The ICC for the pain measures ranged from 0.95 to 0.99. The SEM for pressure pain threshold ranged from 5.57 to 12.00 kPa, and the thermal pain threshold SEM ranged from 0.22 to 0.74C. Note that both the size of the error (SEM) and the ICC are indicative of reliable measures.

Data management and analysis

Two independent variables were incorporated into the research design; TREATMENT (MWM, placebo, control), and TIME of application (pre- and post-intervention). Three dependent variables, measures of pressure pain threshold (PPT), thermal pain threshold (TPT) and dorsiflexion (DF), were evaluated. Prior to analysis, triplicate DF, PPT and TPT data were averaged. Data pertaining to two of the participants were excluded from analysis; subject 4 who had a post-testing MRI that revealed an osteochondral lesion of the talus and ankle joint effusion, and subject 7 who experienced pain during the MWM technique. Pre-experiment differences between sides (symptomatic–
asymptomatic) were evaluated by paired t-tests ða ¼ 0:05Þ: A two-factor analysis of variance (ANOVA) was then performed on each of the three dependent variables to test the hypothesis that MWM produced changes in excess of placebo and control from pre- to postapplication. Any significant interaction effects were followed up with tests of simple effects. Post hoc tests of main effects were performed in the absence of an interaction. A Bonferroni adjustment ðaadjusted ¼ 0:05=3 ¼ 0:017Þ was used to interpret results of the pair wise tests of simple effects and to adjust for any type I error resulting from multiple comparisons.

Results

Pre-experiment deficits in outcome measures: Pre-experiment values for dorsiflexion and pain measures of the affected and unaffected ankles are displayed in Table 2. Statistical analysis of side-to-side differences revealed a deficit only for dorsiflexion (DF) (t ¼ 5:689; Po0:001) and pressure pain threshold over the anterior talofibular ligament (PPT ATFL) (t ¼ 2:570; P ¼ 0:025). No such deficits in thermal pain threshold (TPT) were found.

Primary study
Dorsiflexion: A significant interaction time by condition effect for the dorsiflexion outcome measure was detected by the ANOVA (Fð2;26Þ ¼ 7:817; P ¼ 0:002). The interaction plot is shown in Fig. 2. Post hoc analysis revealed a significant treatment effect for dorsiflexion from pre- to post-application (t ¼ 2:870; P ¼ 0:013). The post hoc analysis for the pre- and post-application data showed no significant differences between the placebo (t ¼ 1:343; P ¼ 0:202) and control (t ¼ 1:324; P ¼ 0:208) conditions. Table 3 presents the dorsiflexion data.

figure2 table2 table3 table4

Pain: The data for pain thresholds for pressure, cold and heat stimuli are expressed as mean and standard deviation in Table 4. Statistical analysis of the pain related data revealed no interaction effects (see Fig. 2 for plots). However, there were main effects for time for PPT ATFL (Fð1;13Þ ¼ 6:401; P ¼ 0:025) and PPT TA (Fð1;13Þ ¼ 9:17; P ¼ 0:010). Post hoc tests of simple effects demonstrated significant pre- to post-differences for PPT ATFL in the placebo condition (t ¼ 2:774; P ¼ 0:016) (Fig. 3), but no significant change in PPT TA. No significant time or condition effects were evident for PPT CFL, or the TPT measures.

Discussion

Application of the dorsiflexion mobilization with movement (MWM) technique to patients with subacute lateral ankle sprains produced a significant immediate improvement in dorsiflexion, but had no significant initial effect on mechanical and thermal pain threshold measures. This dorsiflexion gain following manipulative therapy parallels findings by Green et al. (2001) in acute ankle injuries, and Vicenzino and colleagues’ (2001) study of asymptomatic minimally restricted ankles. Current and previous research findings suggest that the predominant mechanism of action for the dorsiflexion MWM technique is most likely mechanical, rather than a direct hypoalgesic effect. An excessive anterior displacement of the talus is believed to occur during plantarflexion/inversion injury and persist with residual laxity of the anterior talofibular ligament (ATFL) (Mulligan, 1999). Denegar et al. (2002) reported increased ATFL laxity and restricted posterior talar glide in twelve athletes who had sustained an ankle sprain 6 months earlier and had since returned to sport. The clinical rationale given for the anteroposterior glide component of the weight-bearing dorsiflexion MWM technique is to reduce any residual anterior displacement of the talus (Mulligan, 1999). Mulligan (1993, 1999) proposed that correction of the restricted posterior glide, via repetitions of DF with a sustained anteroposterior talar mobilization (mechanically similar to posteroanterior tibial glide on talus), restores the normal joint kinematics even after release of the glide. The mechanism by which this occurs in the presence of ATFL laxity requires further examination. Despite the presence of a reduction in pressure pain threshold (PPT) over the ATFL, the MWM technique did not produce a significant change in local PPT in the initial post-treatment period. The dorsiflexion MWM’s mechanism of action therefore appears to be mechanical, and not directly via changes in the pain system. The conduct of further research is required to identify a precise mechanism. While small but non-significant increases in pressure pain threshold occurred following treatment and control application, it was the placebo condition that produced a statistically significant improvement in pressure pain threshold over the ATFL. It is possible that the gentle inner range dorsiflexion movement performed during the placebo condition was more successful at altering the local pathophysiology peripherally at the ankle or via central neurophysiological mechanisms than the sustained end of range glide and larger range movement of the MWM technique. The application of small amplitude accessory glides of joints in an acute and painful state has been previously advocated (Maitland, 1985) and their benefits in the subacute population requires further investigation. The reasonably small sample size should also be considered to have influenced the results of the statistical analysis. It is possible that the pain measures have a lower sensitivity to change than the dorsiflexion measure, yet the significant dorsiflexion improvement seen post-treatment indicates that range gains are the predominant effect. In addition the failure to elicit prestudy deficits in thermal pain thresholds most likely lessened the likelihood of detecting a change with treatment. Research using a larger sample size and possibly acute ankle sprains with deficits in thermal
pain, should they exist, may reveal differences not detected in this study.

Conclusion

Mulligan’s dorsiflexion mobilization with movement technique significantly increases talocrural dorsiflexion initially after application in subacute ankle sprains. The absence of hypoalgesia post-application suggests a predominant mechanical rather than hypoalgesic effect behind the technique’s success. Further research using a larger sample is required to determine the exact mechanism behind this.

Hydrotherapy on exercise capacity, muscle strength and quality of life in patients with heart failure: A meta-analysis

Mansueto Gomes Neto, Cristiano Sena Conceição, Fabio Luciano Arcanjo de Jesus , Vitor Oliveira Carvalho

Heart failure (HF) is clinically characterized by exercise intolerance, poor health related quality of life (HRQOL) and high mortality. Exercise training is a well-established method to improve exercise intolerance and to restore HRQOL in patients with HF. However, the most efficient modality is unknown. In this context, hydrotherapy (i.e. exercise in warm water) has been proposed as an alternative tool in the rehabilitation of patients with HF. There is no meta-analysis of the efficacy of this intervention in HF patients. The aim of this systematic review with meta-analysis was to analyze the published randomized controlled trials (RCTs) that investigated the effects of hydrotherapy on exercise capacity and HRQOL in HF patients. This review was planned and conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We searched for references on MEDLINE, EMBASE, CINAHL, PEDro, and the Cochrane Library up to May 2014 without language restrictions. This systematic review included all RCTs that studied the effects of hydrotherapy in aerobic capacity, muscle strength and/or HRQOL of the HF patients. Two authors independently evaluated and extracted data from the published reports. Methodological quality was also independently assessed by two researchers. Studies were scored on the PEDro scale a useful tool for assessing the quality of physical therapy trials based on a Delphi list that consisted of 11 items with a score range of 0 to 10.

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Pooled-effect estimates were obtained by comparing the least square mean percentage change from baseline to study end for each group. Two comparisons were made: hydrotherapy versus control group (non exercise) and hydrotherapy versus aerobic exercise group. All analyses were conducted using Review Manager Version 5.0 (Cochrane Collaboration). Six papers met the eligibility criteria. Fig. 1 shows the PRISMA flow diagram of studies in this review. The results of the assessment of the PEDro scale are presented individually in Table 1. The final sample size for the selected studies ranged from 14 to 25 and mean age of participants ranged from 51 to 75 years. All studies analyzed in this review included outpatients with documented HF and New York Heart Association (NYHA) classes II–III. Table 2 summarizes the characteristics. Hydrotherapy was considered as aerobic and strength exercises in warm water and the duration of the programs ranged from 3 to 24 weeks. Regarding the time of the session, there was a variation from 30  to 90 minutes. The frequency of sessions was three times per week in three studies and five times per week in others. Four studies assessed peak VO2 as an outcome, two compared hydrotherapy versus no exercise [10,11] and two hydrotherapy versus conventional aerobic exercise in land. The meta-analyses showed a significant improvement in peak VO2 of 2.97 mL·kg−1 ·min−1 (95% CI: 1.99, 3.94, N = 42) for participants in the hydrotherapy group compared with the no exercise group (Fig. 2A). A non significant change in peak VO2 of −0.66 mL·kg−1 ·min−1 (95% CI: −2.05, 0.72, N = 48) was found for participants in the hydrotherapy group compared with conventional aerobic exercises (Fig. 2B). Three studies assessed the 6-minute walk test (6WMT) as an outcome [10,11,14], two compared hydrotherapy versus no exercise and one hydrotherapy versus aerobic exercises in land. Significant improvements were found when comparing hydrotherapy with no exercise controls. The meta-analyses showed (Fig. 3) a significant improvement in 6WMT of 43.8 m (95% CI: 7.36, 80.16, N = 42) for participants in the hydrotherapy group compared with the no exercise group. Three studies assessed muscle strength as an outcome, two compared hydrotherapy versus no exercise and one hydrotherapy versus aerobic exercise in land. Significant improvements were found when comparing hydrotherapy with no exercise controls. The meta-analyses showed (Fig. 4) a significant improvement in muscle strength of 23.7 Nm (95% CI: 4.49, 42.89, N = 42) for participants in the hydrotherapy group compared with the no exercise group. Two studies measured HRQOL. The meta-analyses showed non significant improvement in HRQOL of −4.5 (95% CI: −14.40, 5.49, N = 42) for participants in the hydrotherapy group compared with the no exercise group (Fig. 5). Meta-analysis demonstrated a significant difference in peak VO2, distance in the six-minute walking test, muscle strength and DBP between patients with HF submitted to hydrotherapy and controls. Moreover, hydrotherapy was as efficient as conventional aerobic exercise in land for peak VO2. It is now known that cardiac function actually improves during water immersion due to the increase in early diastolic filling and decrease in heart rate, resulting in improvements in stroke volume and ejection fraction. These data created a positive scenario to discuss hydrotherapy as a potential tool in cardiovascular rehabilitation. This systematic review with meta-analysis is important because it analyzes the hydrotherapy as a potential co-adjutant modality in the rehabilitation of patients with HF. The mean of peak VO2 in the analyzed studies was 17.05 at the beginning and 18.3 mL·kg−1 ·min−1 at the end of the intervention. It has been demonstrated that improvements above 10% after a cardiovascular rehabilitation program represent a good prognosis in patients with HF. It has also been demonstrated that a minimum VO2 peak of 15 mL·kg−1 ·min−1 in women and 18 mL·kg−1 ·min−1 in men aged 55–86 years seems to be necessary for full and independent living. Thus the improvement generated by the hydrotherapy program can contribute to those patients with CHF to have better conditions to carry out their everyday activities.

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Quadriceps mass and strength are related to maximal exercise capacity in HF. Moreover, changes in muscle performance with exercise training have been demonstrated to be related to changes in physical function and quality of life. In the present systematic review, our meta-analysis demonstrated a significant difference in muscle strength between patients with HF submitted to hydrotherapy and sedentary controls. Despite the fact that hydrotherapy was shown to be efficient in improving peak VO2 and muscle strength, it is not possible to conclude about the benefits of hydrotherapy compared to no exercise in HRQOL. Considering the available data, our meta-analysis showed that hydrotherapy was efficient to improve exercise capacity in patients with HF. Well controlled RCTs are needed to understand the potential bene- fits of hydrotherapy in patients with HF.

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Síndrome femoropatelar, via Instituto Trata

O que é?

A Síndrome da Dor Femoropatelar (SDFP) é ocasionada por um desequilíbrio biomecânico, que atinge a articulação do joelho, mais especificamente a articulação entre o fêmur e a patela. Acomete até 25% da população, sendo mais comum em mulheres sedentárias e indivíduos com grau de treinamento elevado.

Causa
Diversas causas podem estar relacionadas com a SDFP como: largura excessiva da pelve, joelho valgo, fraqueza muscular dos músculos do quadril e da coxa, patela alta, insuficiência ligamentar, dentre outros.

Sintomas

Dor na região anterior do joelho, ao subir e descer escadas, ao agachar e saltar, após longo período sentado (sinal do cinema), estalos ao andar e correr, sensação de areia dentro da articulação.

Diagnóstico e exames

Um exame físico deve ser realizado pelo fisioterapeuta especializado ou médico a fim de avaliar prováveis insuficiências de partes moles, acometimento de estruturas articulares, além de fatores que afetem as força e o alinhamento articular.

Tratamentos
O tratamento depende da causa da dor no joelho, sendo geralmente conservador, baseado em técnicas de Fisioterapia. A fisioterapia específica visa melhorar o deslizamento da patela sobre o sulco troclear no fêmur, utilizando exercícios de fortalecimento muscular e correção biomecânica. Os resultados das sessões de fisioterapia vão depender das características individuais de cada paciente.

Postagem original: http://ojoelho.com.br/sindrome-da-dor-femoropatelar/

Contrologia no Pilates

Quem conhece um pouco sobre a história do Pilates sabe que o nome dado ao método por Joseph Pilates era “contrologia”. Isso porque o mais importante para ele era o controle total do corpo e da mente, por meio dos exercícios e dos princípios, traçados abaixo:

Respiração:
A respiração é um dos princípios mais importantes do método Pilates, e por este motivo está presente em todos os exercícios. Devemos usar um padrão respiratório eupneico (não aumentar nem diminuir a frequência respiratória), utilizando a parte inferior do tronco.
Concentração:
A concentração está diretamente relacionada com a atenção. Para realizar um exercício com concentração, precisamos estar atentos a todos os estímulos que recebemos. Devemos nos concentrar em cada parte do corpo, na sua disposição e se o alinhamento está correto.

Alinhamento Postural:
Melhorar a postura é um dos motivos que levam milhares de pessoas a procurar o método Pilates. Todas as estruturas do corpo devem estar alinhadas durante a prática do Pilates.

Controle:
Ter controle é realizar os movimentos com consciência, evitando compensações musculares e posições indesejadas. É realizar o exercício de forma exata, tendo plena noção de que ele está saindo da forma planejada, sem que as outras regiões do corpo sejam afetadas pelo movimento.

Fluidez:
A fluidez é o princípio que garante que todos os movimentos sejam leves e harmoniosos, sempre seguindo o ritmo da respiração.

Precisão:
A precisão, assim como a concentração, também ajuda a unir corpo e mente. Ela também está muito ligada ao controle, pois juntos eles garantem movimentos precisos e controlados, sendo a chave para exercícios com o máximo de eficiência e o mínimo de lesão.

Centralização da força:
A centralização da força é um dos focos mais importantes da técnica do Pilates. Durante todos os exercícios é necessário estar com o centro do corpo ativado e estável, por meio da contração dos músculos do tronco.

[Informações via Revista Pilates, publicação no dia 29.04.2015: http://revistapilates.com.br/2015/04/29/principios-da-contrologia/]

Estudo comparativo de lesões musculoesqueléticas em diferentes modalidades de capoeira

Mansueto Gomes Neto(1), Meirijane Conceição do Rosário(2), Fabio Luciano Arcanjo(3), Cristiano Sena Conceição(3). Universidade Federal da Bahia –Salvador, BA – Brasil.

INTRODUÇÃO

A Capoeira foi originada no Brasil no século XVIII, na época da colonização, uma manifestação cultural que houve evolução para um esporte nacional brasileiro. Um esporte de agilidade corporal, equilíbrio, destreza, golpes de defesa e ataque, com coreografias, saltos, aterrissagens. Teve influência de esporte existente na época como: judô, jiu-jítsu, karatê, tae-kwon-do e lutas livres. Atualmente existem duas modalidades de capoeira praticada no Brasil, a capoeira Angola, criada na época da escravidão com fundamentos, flexibilidade, com os golpes lentos, baixa velocidade, onde grande parte dos movimentos requer ambas as mãos no chão, as pernas são levantadas com pouca altura, flexionadas, com o tronco e a cintura baixa. A capoeira Regional foi modificada incorporando técnicas de outras lutas, com movimentos de agarramentos, golpes de ponta pé, golpe de mão influenciada do boxe, com movimentos velozes e bruscos, movimentos acrobáticos (saltos), pernadas rápidas.

As manobras e golpes desenvolvidos na capoeira preconizam-se por movimentos circulares comumente realizados no solo e, na maioria das vezes de cabeça pra baixo, em que ocorre a sobrecarga no aparelho locomotor, e o corpo sofre com constantes giros, acarretando impactos nas articulações durante a competição ou treinamento. Atividades com repetição de movimentos, impacto e sobrecarga, aumentam as chances de lesões principalmente em atletas mal condicionados, que realizam golpes de forma inadequada. Um bom treinamento requer organização, acompanhamento, exercícios funcionais que orientem a execução da modalidade desejada. Fradkin et al.(41) realizaram uma revisão sistemática, na qual investigou-se os efeitos do aquecimento sobre a prevenção de lesões, a maioria dos estudos estudados reportaram que o aquecimento realizado antes do exercício reduziu significativamente a incidência de lesão. É imprescindível um tempo de recuperação das estruturas do sistema motor após um treino intenso.

Algumas lesões podem ser desenvolvidas na prática de capoeira como: distensão, contusão, estiramento, contratura muscular, entorses. Durante a ginga, saltos, deslocamento de direção, e na execução de alguns golpes. A combinação de diferentes fatores, como a organização esportiva, o treinamento técnico, o sistema de competições e a falta de estrutura adequada, pode favorecer riscos para a saúde dos praticantes. É importante identificar os fatores que levam a lesões musculoesqueléticas em praticantes de capoeira, por ser um esporte de impacto, aumentando a chance de lesões por sobrecarga, treinos intensos, repetitivos e deslocamentos rápidos dos movimentos ou pela realização inadequada da técnica. Além disso, são escassos estudos biodinâmicos em capoeira e conhecer o perfil das lesões de acordo com o tipo de capoeira realizado pode contribuir para que sejam elaboradas estratégias que possam minimizar as lesões durante a prática. Assim, o objetivo do estudo foi comparar a frequência de lesões em diferentes modalidades de capoeira e identificar possíveis fatores associados.

MÉTODOS

Foi realizado um estudo transversal e analítico, que foi realizado nas academias de grupo de capoeira Angola e Regional da cidade de Salvador Bahia. A amostra foi constituída por 49 voluntários, de ambos os sexos, graduados e que não praticassem outras atividades físicas e/ou esportivas. No inicio todos os atleta foram orientado quanto á pesquisa, posteriormente assinaram um termo de consentimento formal livre e esclarecido de acordo com a resolução nº 196/96 do conselho nacional de saúde, o projeto foi aprovado com o protocolo nº 3440, na reunião plenária do CEP / IMES. Os voluntários foram submetidos a responder um questionário elaborado auto-aplicável, com questões fechadas, onde foi respondido individualmente e a caneta, na academia e em sua residência. O questionário foi explicado ao ser entregue, o tempo médio estimado da aplicação foi de um dia. O questionário foi elaborado pelos autores, contendo 12 questões, com dados pessoais do atleta, incluindo sexo, idade, etnia e questões relacionadas a pratica da capoeira, como tempo de prática, a frequência de treinos por semana, o tempo em horas de cada treino, graduação, se o atleta pratica outro esporte além da capoeira, o treino de capoeira por quem era preparado e se o treinamento e acompanhado pelo treinador. Na terceira parte foram realizadas perguntas relativa a lesão, histórico de lesão, numero de vezes que ocorreu a lesão, localizações das lesões, se a lesão foi em treino ou competição, tempo de afastamento do treinamento por parte do atleta devido à lesão, se a lesão foi diagnosticada por médico, tipo de diagnostico e método utilizado para o treinamento.

Estatística descritiva foi realizada para análise dos dados demográficos e clínicos, os dados de variáveis contínuas e categorias. Para análise da normalidade dos dados foi utilizado o teste Kolmogorov-Smirnov. Como os dados foram distribuídos de forma paramétrica, o teste t de estudente para amostras independentes e o qui-quadrado x² foram utilizados para comparação das variáveis do estudo entre grupos. A análise foi realizada com uso do software SPSS (Statistical Package for the Social Sciences) for Windows (versão 14.0), foi estabelecido um nível de significância α = 0,05.

RESULTADOS

Não houve diferença estatisticamente significativa entre idade e sexo na comparação entre grupos p>0,05. Na comparação da frequência e de lesão e numero de lesões houve diferença significativa (p<0,05) entre os grupos, com maior frequência e numero de lesões na modalidade regional. Na capoeira Regional, lesão 1 o local mais acometido foi o joelho com 6 (25,0%), seguido de ombro 4(16,7%), punho 3(12,5%), lombar 2(8,3%), coxa 2(8,3%), e pé 1(4,2%) 3(12,0%), coxa 1(4,0%), pé 1(4,0%), os tipos de lesão foram tipo 1 na capoeira Regional, houve luxação 6(25,0%), lesão muscular 3(12,5%), fratura 3(12,3%), contusão 2(8,3%), dor lombar 2(8,3%), entorse 1(4,2%), sem diagnóstico 1(4,2 2(8,0%), lesão muscular 2(8,0%), luxação 2(8,0%), entorse 1 (4,0%), e fratura 1(4,0%). Na lesão 2, na Regional tornozelo 5(20,8%), punho 2(8,3%), braço ( 4,2%), coxa 1(4,2%), joelho 1 (4,2%), e pé 1 (4,2%). tipo 2, entorse 3 (12,5%), lesão muscular 3 (12,5%), contusão 2 (8,3%), luxação 2 (8,3%), fratura 1(4,2%). Lesão 3 , lombar 2(8,3%), punho 1(4,2%), braço 1(4,2%), tornozelo 1 (4,2%), tipo 3 dor lombar 2 (8,3%), lesão muscular 2 (8,3%), contusão 1(4,2%). Na capoeira Angola o local mais acometido foi o ombro 3(12,0%), tornozelo 3(12,0%), coxa 1(4,0%), pé 1(4,0%). Tipo de lesão foram contusão 2 (8,0%), lesão muscular 2(8,0%), luxação 2(8,0%), entorse 1(4,0%) e fratura 1(4,0%). Na capoeira Regional o treino preparado pelo mestre dos 23(95,8%), e pelo próprio atleta foi de 1(4,2%), na capoeira Angola o treino preparado pelo mestre foi de 24(96,0%), e 1 (4,0%) pelo atleta. Na Regional o treino acompanhado o tempo todo foi 21(87,5%), parte do tempo 1(4,2%), não acompanhado 2(8,3%), já na Angola o treino acompanhado todo o tempo foi 24(96,0%), e não acompanhado 1(4,0%).

DISCUSSÃO

Neste estudo os resultados obtidos revelam que a capoeira Regional é a modalidade que leva maior índice de lesões em seus praticantes. Moraes em seu estudo informa que o estilo de capoeira com o maior adepto a lesão foi a Regional, onde os movimentos e golpes são bruscos e em alta velocidade, estando os praticantes mais suscetíveis às lesões, diferente da Angola. Os segmentos mais acometidos na capoeira Regional foram joelhos e tornozelos, foram encontrados resultados semelhantes em outros estudos, Signoret (2009). Dos 16 capoeiristas avaliados, cerca de (68,75%), sofreram lesões e os segmentos mais acometidos foi os tornozelos e pés (31,25%), seguido de face, ombro, mãos, e joelhos em menores proporções. Bonfim et al, relata que as lesões no joelho, ligamento cruzado anterior, ocorrem nas praticas esportivas, naquelas que envolvem rotação e saltos. As lesões do ligamento colateral medial e meniscos, também são comuns e responsáveis por uma considerável quantidade de tempo nos esportes. Sena et al observou que as lesões de joelho, com predominância de ligamento cruzado anterior e menisco, pode ocorrer em decorrência da postura do individuo, estando mais sujeito a acontecer através dos deslocamentos rápidos (ginga, golpes, e giratórios), repetições de movimentos, devido também ao pé de apoio no solo, ocasionando a força de atrito e resultando na força de reação do solo, onde dependendo do piso e o individuo estando descalço será menor e calçados será maior. Em outro estudo relatam que as lesões do joelho em capoeiristas também podem estar associadas ao excesso de peso do corpo, repetições dos movimentos de flexo-extensão, provocando desgaste nesta articulação. Roquette et al (1994) descrevem vários fatores que ocasionam desgaste na estrutura física do atleta, o frequente impacto advindo de quedas, a forma de aterrissagem são um dos fatores desencadeante de lesões musculares. Achour Júnior (1995) salienta que as habilidades atléticas que não exploram o movimento em Tabela 1. Características demográficas e frequência de lesão entre modalidades.

Brennecke et al (2000), afirmam que uns dos movimentos que podem gerar maior carga externa dentre os movimentos da capoeira estudado e a “armada pulada” e o “parafuso”, pode causar lesões em diversas estruturas biológicas, deve ser evitada as repetições desses movimentos no treino, já que em competição dificilmente se executa os mesmos movimentos diversas vezes. Segundo Kendal et al (1995), os capoeiristas para realizar algumas manobras, ocorre o mecanismo compensatório da coluna vertebral, para aumentar o ângulo do chute, e acaba desenvolvendo encurtamento dos músculos e dores na coluna vertebral. No estudo mostra que a prevalência de lesões musculoesqueléticas assemelha-se entre homens e mulheres e em diferentes idades. Moraes et al correlaciona a dor lombar e o sexo, mostrando significativa (p=0,001), e foi mais notada em capoeiristas do sexo feminino(55%). Papageorgiou et al. afirmam em seu estudo que a prevalência de lombalgia em relação a diferença de sexo, variaria também, de acordo com a idade. Observou que abaixo de 30 anos atacou as mulheres, 45 e 59 anos, foi mais frequente nos homens. Junior, diz que aproximadamente 54% das pessoas que jogam capoeira utilizando calçados, sentem dores na região do menisco e na região lombar, pois essas lesões estão associadas aos calçados que não são apropriados para treino ou competição. E a modalidade que costuma usar calçados é a Angola. O treinamento foi executado 3 vezes por semana com tempo de treino 2 horas diária. Esportes competitivos, como os de lutas, obrigam a treinamentos intensos e longos, havendo sem duvida sobrecarga ao corpo humano, e neste aspecto, o joelho fica vulnerável, seja em atletas ou esportistas. Em relação ao tipo de lesões, na capoeira Regional foi mais frequente a luxação e fratura, na Angola foi a lesão muscular e contusão, as lesões ocorreram em ambos os sexos e idades, enquanto que em outro estudo, houve maior prevalência de dor lombar e mais frequente no sexo feminino. Nos esportes de contato, o atleta é ainda mais suscetível, pois além destes fatores, ainda esta envolvido o peso do outro atleta, levando a uma maior sobrecarga. Os capoeiristas relataram não realizar outras atividades físicas além da capoeira, o que demonstra sua fidelidade ao esporte, com frequência regular e dedicação de tempo semanal. Apesar do acompanhamento e orientação dos treinos pelo mestre, a alta taxa de lesão é preocupante. Assim, uma completa avaliação musculoesquelética de um atleta previamente lesado e um completo planejamento de prevenção e reabilitação pode ser o meio mais efetivo para diagnosticar e controlar as lesões esportivas. Conclui-se que a modalidade Regional por utilização de movimentos bruscos tem maior prevalência de lesões do tipo luxação, fratura, que acometem principalmente o joelho, tornozelo, seguido do ombro, na capoeira Angola, o local mais acometido foi ombro e tornozelo, os tipos de lesões foram: contusão, lesão muscular.

Effects of the FIFA 11 training program on injury prevention and performance in football players: A systematic review and meta-analysis

Mansueto Gomes Neto, Cristiano Sena Conceição, Alécio Jorge Alves de Lima Brasileiro, Camila Santana de Sousa, Vitor Oliveira Carvalho and Fabio Luciano Arcanjo de Jesus.

Objective: To investigate the effects of FIFA 11 training on injury prevention and performance in football players. Design and methods: Systematic review and meta-analysis. We conducted a systematic search using four databases (CINAHL, Cochrane Library, EMBASE, and PubMed) to find controlled trials evaluating the effects of FIFA 11 on injury prevention and performance among football players. Weighted mean differences, standard mean differences, risk ratios, and 95% confidence intervals were calculated, and heterogeneity was assessed using the I2 test.

Results: We analyzed 11 trials, including 4700 participants. FIFA 11 resulted in a significant reduction in injury risk (risk ratio = 0.69; 95% confidence interval, 0.49–0.98; P = 0.02) and improvements in dynamic balance (weighted mean difference = 2.68; 95% confidence interval, 0.44–4.92; P = 0.02) and agility (standard mean difference = −0.36; 95% confidence interval, 0.70–0.02; P = 0.04). The meta-analysis indicated a nonsignificant improvement in jump height (standard mean difference = 0.25; 95% confidence interval, 0.08–0.59; P = 0.14) and running sprint (standard mean difference = −0.24; 95% confidence interval, 0.58–0.10; P = 0.17) in the FIFA 11 group.

Conclusions: FIFA 11 can be considered as a tool to reduce the risk of injury. It may improve dynamic balance and agility and can be considered for inclusion in the training of football players.

Background: Despite scientific advances in the understanding of injury mechanisms and screening techniques, the high injury rate in football players persists and is among the highest in sports. Junge and Dvorak, reported 10 to 35 injuries per 1000 hours of match play and two to seven per 1000 hours of training in international football players. Studies have described risk factors for football players’ injuries and discussed possible strategies for prevention, however, few programs incorporate football-specific components. Moreover, extensive time and special equipment are needed for these programs to be effective. A warm-up program called FIFA 11, developed with the support of the World Football Association (FIFA), was proposed as a complete warm-up focusing on prevention of football injuries.6 The FIFA 11 program requires no technical equipment other than a ball and can be completed in 10–15 minutes. In addition, other programs used in prevention protocols have also been shown to have performance effects among football players. A recent systematic review was performed to evaluate the impact of FIFA 11 on the incidence of injury, compliance, and cost effectiveness among football players. The authors reported considerable reductions in the number of injured players (ranging between 30% and 70%). However, individual studies reported conflicting results, and the authors did not perform any metaanalysis. Hence, the effects of FIFA 11 are still unknown. In addition, to the best of our knowledge, no meta-analysis of the effects of FIFA 11 on performance among football players has been published to date. The aim of this systematic review with meta-analysis was to analyze the published randomized controlled trials (RCTs) that have investigated the effects of FIFA 11 on injury prevention and exercise performance among football players.

Methods: This meta-analysis was completed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Eligibility criteria: This systematic review included RCTs that investigated the effects of FIFA 11 on injury prevention and exercise performance of football players. Trials enrolling football players were included in this systematic review. To be eligible, the trial must have randomized football players to a single group in which the FIFA 11 program was performed at least two times per week for at least four weeks. Studies that enrolled non-athletes or athletes from other sports were excluded. The main outcomes of interest were injury and exercise performance (balance, running sprint, and agility). Search methods used to identify studies We searched MEDLINE, PEDro, EMBASE, SciELO, Cumulative Index to Nursing and Allied Health (CINAHL), and the Cochrane Library for relevant studies published up to August 2016 without language restrictions. A standard protocol for this search was developed and whenever possible, controlled vocabulary (MESH terms for MEDLINE and Cochrane and EMTREE for EMBASE) was used. Keywords and their synonymous were used to sensitize the search. The strategy developed for the Cochrane Collaboration10 included study design, participants, and interventions, was used to identify the RCTs. The references of the eligible articles for this systematic review were analyzed to detect other potentially eligible studies. Authors were contacted by email for ongoing studies or when the confirmation of data or additional information was needed. Data collection and analysis The titles and abstracts identified in the search strategy were screened by two independent reviewers. If, at least, one of the authors considered one reference eligible, the full text was obtained for complete assessment. The reviewers independently evaluated full-text articles for eligibility using inclusion and exclusion criteria. In case of any disagreement, all of the authors discussed the reasons for their decisions and a final
decision was made by consensus. Two authors independently extracted data from the published reports using standard forms adapted from the Cochrane Collaboration’s10 model for data extraction. Aspects of the study population, intervention, follow-up and loss to follow-up, outcome measures, and results were reviewed. Disagreements were resolved by one of the authors. Any further information required from the original author was requested by email.

Quality of meta-analysis evidence: The quality of the RCTs was classified by two researchers using the PEDro scale, which is based on concealed allocation, intention-to-treat analysis, and adequacy of follow-up. These characteristics make the PEDro scale a useful tool for assessing the quality of physiotherapy and rehabilitation
trials. The PEDro scale consists of 11 items and is based on a Delphi list.12 One item on the PEDro scale (eligibility criteria) is related to external validity and is generally not used to calculate the method score, leaving a score range of 0 to 10.13 Any disagreements were resolved by a third investigator.

Data analysis: Pooled-effect estimates were obtained by comparing the least-square mean percentage change from baseline to study end for each group and were expressed as the weighted mean difference (WMD), standard mean difference (SMD), or risk ratio (RR) between the groups. Calculations were done using a random-effects model. When the standard deviation (SD) of change was not available, the SD of the baseline measure was used for the meta-analysis. One comparison was made: FIFA 11 vs. the control group. An α value of 0.05 was considered significant. Statistical heterogeneity of the treatment effect among studies was assessed using Cochran’s Q-test and the inconsistency I2 test, in which values above 25% and 50% were considered indicative of moderate and high heterogeneity, respectively.14 All analyses were conducted using Review Manager Version 5.0 (Cochrane Collaboration).

Results: The initial search led to the identification of 302 abstracts, from which 24 studies were considered as potentially relevant and retrieved for full-text analysis. After the complete reading, 13 studies were excluded. Finally, 11 articles16–26 met our eligibility criteria. Figure 1 shows the PRISMA flow diagram of included studies in this study. The results of the PEDro scale are presented individually in Table 1 (available online). Of the 11 included articles, five investigated exercise performance in FIFA 11 vs. control groups,16–20 whereas the other six studies investigated injury prevention in FIFA 11 vs. controls. The final sample ranged from 2419 to 202024 football players. Mean age of participants ranged from 39.316 to 46.223 years. Table 2 summarizes the included participants, sample size, outcomes, and results of the included studies. The parameters used in the application of FIFA 11 were reported in most studies. Table 3 (available online) summarizes the FIFA 11 characteristics of included studies. Figure 2 shows the meta-analysis of injury prevention between FIFA 11 and control groups. The RR was 0.64 (95% CI, 0.43 to 0.96), indicating a significant reduction of risk of injury in the FIFA 11 group (P = 0.03). Figure 3 shows the meta-analysis of dynamic balance between the FIFA 11 and control groups. For this meta-analysis, two studies were included. The total number of subjects in the FIFA 11 group was 54, whereas 51 subjects were included in the control group. FIFA 11 treatment significantly enhanced dynamic balance (WMD = 2.68; 95% confidence interval (CI), 0.44 to 4.92; P = 0.02) when compared with the control group. Figure 4 shows the meta-analysis of agility between the FIFA 11 and control groups. For this meta-analysis, three studies were included. The total number of subjects in the FIFA 11 group was 68, whereas 68 subjects were included in the control group. Analysis of agility showed significant improvements with FIFA 11 vs. control (SMD = −0.36; 95% CI, –0.70 to –0.02; P = 0.04). Figure 5 shows the meta-analysis of jump height between the FIFA 11 and control groups. For this meta-analysis, three studies were included. The total number of subjects in the FIFA 11 group was 68, whereas 68 subjects were included in the control group. This analysis indicated a non-significant improvement in jump height in the FIFA 11 group (SMD = 0.25; 95% CI, 0.08 to 0.59; P = 0.14). Figure 6 shows the meta-analysis of running sprint between the FIFA 11 and control groups. For this meta-analysis, three studies were included. The total number of subjects in the FIFA 11 group was 71, whereas 65 subjects were included in the control group. This analysis indicated a non-significant improvement in running sprint in the FIFA 11 group (SMD= −0.24; 95% CI, 0.58 to 0.10; P = 0.17).

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Discussion:  The main results of our meta-analysis indicate that FIFA 11 was effective in reducing the rates of injuries in football players. The FIFA 11 program was also effective in increasing dynamic balance and exercise performance in football players. FIFA 11 is a well-established warm-up program widely used to decrease the incidence of injuries among male and female amateur football players. Despite some published studies, we did not find any meta-analysis that evaluated the impact of FIFA 11 on physiological parameters and exercise performance of football players. Barengo et al.,8 performed a systematic review to evaluate the effects of FIFA 11 on injury prevention in football players. However, the study included clinical trials, observational cohort, and explorative studies, and no meta-analysis were performed. This meta-analysis is relevant because it analyzes FIFA 11 as a relevant tool to minimize the risk of injury and at the same time improves exercise performance. Steffen et al.22 reported that a 20-min neuromuscular injury prevention warm-up program improved dynamic and functional balance and reduced by 72% the risk of injury among players that strictly adhered to the intervention during the season. In another study, high adherence to the FIFA 11 resulted in significant improvements in functional balance and a reduction on risk of injury.22 Improvements on neuromuscular control appear to be a key element of FIFA 11, which is associated with improvements on technical and tactical performance of football players. The eligibility of dynamic balance testing as an outcome in this systematic review is important, because the higher the skill levels, the better functional performance that are associated with a lower risk of injury.27 It has been reported that impaired balance is indirectly associated to an increased risk of ankle and knee sprain injuries.28,29 Lower performances on dynamic balance tests is also associated with an elevated injury risk. Butler et al.30 assessed dynamic balance using the Star Excursion Balance Test in 59 football players and reported that those who had a score of less than 89% were at increased risk of injury. Athletes with a positive Star Excursion Balance Test result (<89% limb length composite score) had a substantially higher probability of sustaining a non-contact lower extremity injury (37.7%–68.1%).30 Moreover, proper functional balance and control of the lower extremities are essential for both technical and tactical performance among football players, and such attributes are assumed to decrease the risk of injury.31 Peterson et al. found that young players with low skill levels had a two-fold increased incidence of all injuries when compared with more skilled athletes. FIFA 11 also includes agility and plyometric exercises. Thus, the exercises used in FIFA 11 can be associated with an improvement in agility performance. Although the main aim of the FIFA 11 is injury prevention, the knowledge of training effects elicited by this program can also lead to benefits in exercise performance. FIFA 11 is easy to perform and takes approximately 10–15 minutes. FIFA 11 can be performed and integrated into regular football practice and requires no additional equipment. Thus, professionals can easily add this program for the training of athletes. Given the small amount of available studies, caution is warranted when interpreting our results. Further investigation is required to investigate how to sustain the positive effects of FIFA 11 in football players over time. Considering the moderate quality of the included studies, additional wellcontrolled RCTs are required to reinforce the conclusion that FIFA 11 is an important warm-up program for football players. Additionally, future studies should ensure that intention-to-treat analysis and more adequate randomization procedures are used to reduce the impact of issues related to internal validity. This systematic review with meta analysis showed that FIFA 11 is an important warm-up program that can be used to decrease the rates of injuries, and improve dynamic balance and agility among football players.

Clinical message: FIFA 11 significantly reduces the rate of injury and increases dynamic balance and agility in football players.

Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.

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Relationship between cycling mechanics and core stability

JOHN P. ABT,1 JAMES M. SMOLIGA, MATTHEW J. BRICK, JOHN T. JOLLY, SCOTT M. LEPHART AND FREDDIE H. FU

Introduction

Core stability has received considerable attention with regards to functional training in sports. Anecdotally, core strengthening has been adopted by the athletic community and clinical professionals both for performance enhancement as well as injury prevention, with particular focus related to strengthening the abdominal, paraspinal, and gluteal muscles. The core not only provides stability to the spine while controlling movement at the torso, but also affords greater leverage for upper and lower extremity motion and force development. Specific to cycling, the core provides the foundation from which force is generated. The core muscles maintain the neutral pelvic position on the bike when the anterior and posterior muscle components are equally balanced. On the basis of orientation and attachment of the psoas muscle on the lumbar spine, pelvic stabilization and resistance to fatigue are critical to maintain the natural curve of the spine as well as provide the leverage from which the psoas and gluteal muscles contract when a greater power output is required. Although the lack of core stability would appear to have the greatest influence on the back, lower extremity alignment could also be affected as the foundation from which power is generated becomes compromised. Appropriate bike fitting is critical to prevent injuries such that consistent lower extremity alignment is adopted throughout the pedal stroke. Decreased core strength however, could artificially induce malalignment of the lower extremity in an effort to maintain a given power output. Furthermore, the combined effect of lower extremity malalignment, excessive cadence, and increased riding volume or intensity could increase the risk of injury. The typical cyclist, with an average cadence of 90 revolutions per minute, will pedal between 16,000 and 21,000 revolutions during a typical 3–4-hour ride and upwards of 33,000 for a 6-hour ride. The repetitive motion of cycling and the fixed position of the pelvis and feet require efficient movement patterns to avoid excessive stresses being applied to the musculoskeletal structures of the lower extremity. Although the relationship between core stability and back injury in cyclists has been studied, no research that we are aware of has examined the role of core stability in maintaining lower extremity alignment during cycling. The core is often described according to the perspective of the investigator. For the purpose of this study, the core will refer to the main anterior and posterior lumbo-pevlic stabilizing muscles. The purpose of this study was to determine the relationship between cycling mechanics and core stability. It was hypothesized that diminishing core stability would result in altered cycling mechanics and pedal force application.

Methods

Experimental Approach to the Problem A within-subject, repeated measures design was used to determine changes in lower extremity joint kinematics and pedaling forces as a result of compromised core stability. Subjects reported for 3 sessions (1 training, 2 testing) throughout the study. Sessions were separated by a minimum of 1 week to ensure full recovery and prevent potential confounding results on subsequent tests. An initial training session was provided to introduce subjects to testing methods. Subjects performed an incremental ramp cycling protocol during test 1. Test 2 required the subjects to complete a precore fatigue isokinetic test, core fatigue workout, postcore fatigue isokinetic test, and a repeat of the incremental ramp protocol performed during test 1.

Subjects

Fifteen competitive cyclists (age: 34.5  9.8 years; height: 1.77  0.11 m; mass: 76.3  11.1 kg) participated in this study. Subjects were members of local road cycling teams with a road race classification of category 2–4 on the basis of racing experience and accumulated finishing place points by the U.S. Cycling Federation. Subjects provided written informed consent before participation in accordance with the university Institutional Review Board. Subjects who reported a history of musculoskeletal injury within the previous 3 months or participated in a core strengthening program (2 or more times per week for 6 weeks before study enrollment) on a regular basis were excluded.

Procedures

Training Session. Subjects were provided a separate training session to become familiar with the testing procedures and, specifically, riding on the treadmill (Woodway ELG; Woodway USA, Waukesha, WI). Proper gear ratio was determined during the training session to ensure subjects were able to maintain the desired pace with a cadence of 90–95 revolutions per minute. This would be the gear ratio that subjects would ride during the testing sessions. Incremental Ramp Protocol—Test 1 and Test 2. One week after the training session, subjects reported for test 1. Linear and circumferential anthropometric measurements of the dominant lower extremity were recorded for
each subject. Spherical reflective markers (diameter 0.025 m) were placed at designated anatomical landmarks previously described by Vaughan et al. Two additional markers were positioned at the most lateral aspect of the pedal in line with the pedal spindle and approximately 4.5 cm inferior to the pedal spindle marker. Raw coordinate data were collected with the Peak Motus 3D Motion Analysis System (software version 7.1; ViconPeak Inc., Centennial, CO) interfaced with 8 highspeed (120-Hz) optical cameras (Pulnix Industrial Product Division, Sunnyvale, CA). Dependent kinematic variables included total frontal and sagittal plane motion of the hip and knee and total sagittal plane motion of the ankle. Intraclass correlation coefficients (ICCs) and standard error of measurement (SEM) were previously calculated within our laboratory for test-retest reliability of all kinematic measurements (ICC 0.843–0.957; SEM 0.97–1.89). Raw force data (1,200 Hz) were collected with the use of custom-designed pedals constructed from silicone strain gauge force transducers (ATI Industrial Automation, Apex, NC) and Shimano Pedaling Dynamics (SPD) pedals (Shimano, Osaka, Japan). A local coordinate system was created on the bicycle, with the origin positioned on the seat tube, 5 cm inferior to the seat tube–top tube junction. Two additional markers were positioned on the down tube at the same vertical height as the origin marker and the center of the head tube. The local y-axis was calculated as the vector between the seat tube and down tube markers, whereas the x-axis was formed by the vector between the seat tube and head tube markers. The cross product of the x- and y-axes was used to calculate the z-axis. Dependent variables included power phase effective force, recovery phase effective force, total gross work, total net work, positive work, and negative work. Power phase was defined as the time period that corresponded to 0–180 of the pedal stroke, and recovery phase was defined as the time period that corresponded to 180– 360 of the pedal stroke. Coefficient of variation for pedal force data has been previously determined within our laboratory to be 18.3–24.4%. Coefficient of variation for work data has been previously determined within our laboratory to be 20.7–23.2%. Subjects rode their own bikes and wore their own cycling shoes with SPD cleats (Shimano, SM-SH51) to ensure natural position within the SPD pedal (Shimano, PD-M520). Subjects were provided a 10-minute warm-up before data collection. The treadmill protocol for test 1 and test 2 consisted of riding untethered on a high-speed treadmill at 25.8 km·h1. The treadmill elevation was increased in 1% increments every 3 minutes until exhaustion. Subjects were required to maintain the same gear ratio, cadence, and hand position throughout the test while remaining seated. A total of 7 pedal cycles were collected during the final 30 seconds of each stage, with the middle 3 trials being used for data analysis. Isokinetic Torso Rotation Test—Test 2. The Biodex System 3 Multi-Joint Testing and Rehabilitation System (Biodex Medical Inc., Shirley, NY) was used to validate core fatigue following the core fatigue workout by determining the changes in torque, work, and power after the exercise circuit. Subjects were seated in an upright position with their popliteal space approximately 6 cm from the edge of the seat of the chair. The torso rotation attachment was aligned with the long axis of the spine and lowered to contact the subject’s chest approximately 4 cm below the level of the clavicles. Practice trials were provided to ensure patient understanding and familiarity. Subjects were instructed to perform maximal intensity, concentric isokinetic axial torso rotations at 120·s1 for 3 minutes without pacing. Right and left rotational data were averaged for peak torque, total work, average power, maximum repetition total work, and average peak torque per repetition. Core Fatigue Workout—Test 2. Subjects performed a 32 minute circuit of 7 exercises designed to target core stabilizer muscles in multiple planes of motion. Each subject completed 4 consecutive sets of the exercise circuit, performing each exercise for 40 seconds and resting for 20 seconds. The exercise circuit consisted of the following exercises: seated upper torso rotations with medicine ball, static prone torso extension with medicine ball, supine lower torso rotations with medicine ball, incline sit-ups with weighted plate, lateral side bend (performed bilaterally) with weighted plate, rotating lumbar extension with weighted plate, and standing torso rotations with weighted pulley resistance. Immediately after the exercise circuit, subjects performed a second isokinetic torso rotation test to verify fatigue  of the core musculature. On completion of the postexercise isokinetic test, subjects performed a second incremental cycling treadmill test as described for test 1. Data Reduction. Raw coordinate data were filtered  with a fourth-order Butterworth filter with an optimal cutoff frequency (7). All of the kinematic calculations were performed in the Kincalc module of the Peak Motus software package and based on Vaughan et al. Raw force data were filtered with a fourth-order Butterworth filter with an optimal cutoff frequency. The filtered coordinate and analog data were then exported to a custom-designed LabView (version 6; National Instruments, Austin, TX) program to calculate the joint kinematic and pedal force data of interest. Initially, the pedal markers were converted to the local coordinate system of the bike. The average position of the pedal spindle marker was used to calculate the center of rotation of the crank and the vector from the crank center of rotation to the pedal spindle representing crank length. The vector from the inferior pedal spindle marker to the center pedal spindle marker represented the orientation of the pedal with respect to the crank vector. The pedal forces were initially calculated in their own orientations and then transformed to coincide with the local coordinate system of the bike. Forces in the bike local coordinate system were then transformed to an instantaneous coordinate system coinciding with the circular motion of the bike crank. The tangential force component axis was aligned along the fore/aft direction of the pedal, the normal force component axis was aligned perpendicular to the pedal, and the mediolateral force component was calculated as the cross product of the tangential and normal force directions to coincide with the mediolateral axis of the bike local coordinate system. The effective force (work perpendicular to crank) and ineffective force (work parallel to the crank) components were calculated from the normal and tangential pedal components and as force vectors relative to crank angle. Instantaneous angular work was calculated throughout each crank cycle as the product of the effective force and distance of rotation (arc length  crank length  angular displacement). Total positive work and total negative work were initially calculated as the area under the instantaneous work and crank angle curve. Net work was calculated as the difference between positive and negative work. Gross work was calculated as the sum of the absolute values of positive work and negative work.

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Statistical Analyses

SPSS 11.5 (SPSS, Inc., Chicago, IL) was used for all statistical procedures. Separate dependent t-tests were initially used to analyze differences for isokinetic torso rotation variables (peak torque, total work, average power, maximum repetition total work, and average peak torque per repetition) after the core fatigue workout. Separate dependent t-tests were used to examine kinematic (total frontal and sagittal plane motion of the hip and knee and total sagittal plane motion of the ankle) and force (power phase effective force, recovery phase effective force, total gross work, total net work, positive work, negative work) differences of the final stage attained between test 1 and test 2. Statistical significance was set a priori at p  0.05 for all analyses.

Results

A significant decrease (30.0–43.3%) in peak torque, total work, average power, maximal repetition total work, and average peak torque was demonstrated after the core fatigue workout, confirming the effect of the core fatigue workout to induce fatigue. Isokinetic torso rotational data are presented in Table 1. Because of variability in completion of the incremental ramp protocol between subjects, kinematic and force data are reported at the final stage as subjects self-terminated the test because of exhaustion. Termination of test 1 and test 2 were completed within the same stage within subjects (5  1%). Total frontal plane knee motion and total sagittal plane knee and ankle motion increased (13.4–54.3%) after the core fatigue protocol, indicating greater extraneous motion throughout the pedal stroke. Kinematic data are presented in Table 2. No significant differences were demonstrated for any pedal force or work data. Pedal force and work data are presented in Table 3.

Discussion

The purpose of this study was to determine the relationship between cycling mechanics and core stability. The results of this study only partially supported our hypotheses. Specifically, several of the kinematic variables were altered after the core fatigue workout, whereas the pedal force and work variables remained unchanged. Collectively, these results would suggest compensatory kinematic adaptations to maintain a given power output. Knee pain remains one of the most commonly diagnosed pathologies in cyclists, with factors such as bicycle fit, improper training, and anatomical abnormalities identified as contributors to injury. Considering the fixed pelvis and feet positions, the knee acts as the fulcrum of the thigh and shank, at which point excessive stresses are likely to be absorbed. Cycling mechanics typically involve a pistonlike, symmetrical motion of the legs for power generation and smooth rolling transition between the contact points of the patellofemoral joint. Disrupted tracking of the patella could result in wearing on the posterior surface of the patella because of excessive frontal plane motion of the knee. As identified in this study, disruption of core stability resulted in greater total frontal plane knee motion and altered the cyclical, aerodynamic position of knees near the top tube with a greater valgus positioning toward the top tube. The subjects also displayed a combination of greater total sagittal plane knee motion and total sagittal plane ankle motion. The adopted sagittal plane knee motion pattern could have been a compensatory adaptation as a result of ankling to increase the leverage of the foot against the pedal. The lack of core stability might amplify the influence of the other factors (strength imbalances, flexibility deficits, heavy gear selection, large accumulation of miles) that are known to contribute to knee pathology, particularly as cyclists continue to ride for durations of several hours with altered mechanics of the lower extremity. The application of pedaling forces has been previously studied in normal and prolonged cycling conditions. The typical pedaling stroke is separated into the effective (force application perpendicular to crank arm) and ineffective (force application parallel with crank arm) components. By partitioning the application of pedal forces into the respective components, inefficient force patterns can be identified, particularly as the feet transition through the top and bottom of the pedal stroke. Inefficient force patterns include persistent inferior vertical force at the bottom of the pedal stroke and insufficient superior forces during the recovery phase as the top of the pedal stroke approaches. The role of core stability and subsequent changes in pedaling forces has received limited attention. Sanderson and Black demonstrated an improvement in pedaling effectiveness during the power phase coupled with a reduction in pedaling effectiveness during the recovery phase as a result of prolonged cycling. The authors contended that the increased power phase effective force was a compensatory mechanism to offset the diminished effective force during the recovery phase. The lack of changes in pedaling forces, specifically during the recovery phase, was somewhat surprising considering our hypothesis that disrupting core stability would result in a reduction in pedaling effectiveness during the recovery phase. The lack of differences between test 1 and test 2 for positive work, negative work, net work, and gross work was also not expected. On the basis of our hypotheses, improved pedaling efficiency would have been demonstrated with decreased effective force during the recovery phase or a reduction in negative work. However, considering the response to the pedaling forces after the core fatigue workout, the work data followed a similar pattern and was consistent between the 2 treadmill tests. The fixed speed of the treadmill might have forced the subjects to maintain a similar pedaling efficiency (effective forces, work) between tests in this study in an effort to continue riding at the dictated pace, despite diminished core stability. Combined with the altered knee and ankle kinematic data, it is likely that core fatigue would have resulted in greater power phase effective force and less recovery phase effective force had a manual treadmill or roller system been used to better replicate the environment encountered during daily outside riding because the pace or resistance could be changed freely by the subject. The work of Sanderson and Black further supports the notion that the treadmill speed might have influenced the test results because no changes were demonstrated for either the power phase or recovery phase effective forces despite the kinematic changes. Similarly, Sarre et al. demonstrated greater positive and negative work during pedaling when the cadence increased. Several limitations have been recognized by the authors. The fixed speed and gear ratio within and between tests might have negated the likelihood of finding significance with the pedaling force data. The inability to shift to an easier gear or slow down could have forced the subjects to pedal in a manner that resulted in the same performance, despite the altered mechanics of the lower extremity. Combined with the fixed treadmill speed, it is understandable that no changes were present for the pedal force data because similar pedaling efficiency was required to maintain the same position on the treadmill. The lack of changes in pedal force data further supports the importance of the core in lower extremity cycling mechanics in that the altered kinematic patterns were likely compensatory adaptations to maintain similar force patterns. However, the changes in biomechanical variables indicated that the use of untethered treadmill cycling forced the cyclists to adopt similar stabilizing mechanisms as experienced with outdoor, natural cycling. The core fatigue protocol used in this investigation resulted in a significant reduction in core strength, endurance, and lower extremity alignment as verified by the isokinetic tests and the cycling treadmill tests. Furthermore, the cycling treadmill test of test 2 was started within 5 minutes of completing the isokinetic test to prevent recovery from the induced core fatigue. Although the targeted and acute core fatigue induced during the current study did not evolve in the progressive, low-intensity manner that would occur during natural cycling, the lack of core stabilization as a result of fatigue or weakness might produce a similar outcome regardless of mechanism. The results of this study suggest that core stability contributes to lower extremity cycling mechanics. Improvements in core strength could promote greater torso stability within the saddle and maintenance of lower extremity alignment to apply greater force transmission to the pedals. Future research should examine the role of core fatigue on muscle activity of the specific core muscles, joint mechanics, and pedaling forces during unrestricted, self-pacing cycling that better simulates outdoor riding. Finally, future research should be performed to develop cycling-specific training programs to improve core strength and to determine whether such training programs reduce fatigue-related changes in cycling mechanics. Collectively, these data could be used to determine how core training most effectively influences performance and reduces the risk of injury in cyclists.

Practical applications

The introduction of a core fatigue workout altered the mechanics of the lower extremity during cycling while pedal force application remained unchanged. Prolonged cycling with altered lower extremity mechanics as a result of a fatigued core might increase the risk of overuse injury from malalignment. Cyclists should integrate a yearround core conditioning program into current training to promote lower extremity alignment while cycling. Although cycling is primarily a sagittal plane activity, a core conditioning program should incorporate both sagittal and frontal plane exercises. Strengthening the core musculature could enhance the stability of the foundational leverage from which the cyclist generates power, and increasing the endurance of the core muscles could promote core stability maintenance.

Confira o artigo completo: https://www.ncbi.nlm.nih.gov/pubmed/18076271

Influence of a preventive training program on lower limb kinematics and vertical jump height of male volleyball athletes

Gustavo Leporace, Jomilto Praxedes, Glauber Ribeiro Pereira, Sérgio Medeiros Pinto, Daniel Chagas, Leonardo Metsavaht, Flávio Chame, Luiz Alberto Batista 

1. Introduction

Currently, decision making is an important task in managing a program of sports training. Among other things coaches should decide what physical exercise should be used to improve athletic performance most efficiently. From this point of view, selecting exercises that simultaneously act positively on more than one performance variable, seems an interesting choice. There is evidence that training programs, including plyometric, balance and lumbar-pelvic stability exercises, can contribute to reduce the incidence of ACL injuries in female athletes (Heidt, Sweeterman, Carlonas, Traub, & Tekulve, 2000). Biomechanically, it is believed that these exercises propitiate changes in the kinematic and kinetic lower-limb behaviours related to the mechanism of this type of injury, such as dynamic knee valgus displacement, maximum knee flexion and peak ground reaction forces (Hewett, Stroupe, Nance, & Noyes, 1996; Irmischer et al., 2004; Myer, Ford, Brent, & Hewett, 2006; Myer, Ford, McLean, & Hewett, 2006; Myer, Ford, Palumbo, & Hewett, 2005). Moreover, there is evidence that such training programs can also result in direct improvement of athletic performance variables, mainly those related to vertical jump height (VJH), power and agility. Therefore, it is reasonable to assume that such programs can be used for the purpose of improving the overall performance of athletes (Di Stefano et al., 2010; Luebbers et al., 2003; Myer et al., 2005; Myklebust, Maehlum, Holm, & Bahr, 1998; Newton, Kraemer, & Hakkinen, 1999; Villareal, Gonzalez-Badillo, & Izquierdo, 2008). Nevertheless, although such information might be important for the development of training strategies, its practical use and great widespread requires the overcoming of limitations not addressed in previous studies, particularly with regard to the preventive practice. One of the limitations previously mentioned is the epidemiological indicators associated with the gender of the subjects investigated. In this case, females tend to be more studied, probably because they are more susceptible to ACL injuries, although the prevalence is higher in the male population, likely because more men participate in sports (Renstrom et al., 2008). It seems that ACL injuries result from multi-planar movements and it has been argued that both the risk factors and the injuryinducing mechanisms differ between genders (Hewett, Myer, & Ford, 2005; Krosshaug, Slauterbeck, Engebretsen, & Bahr, 2007; Zazulak, Hewett, Reeves, Goldberg, & Cholewicki, 2007). In women, the injury is primarily associated with dislocations and mechanical load in the sagittal, frontal and transverse planes (Hewett et al., 2005), whereas injuries in men seem to be primarily related to movements and loads in the sagittal plane (Quatman & Hewett, 2009). Specifically, kinematic risk factors in  females are supposed to be related to knee valgus and flexion, associated with tibial rotation and hip adduction (Hewett et al., 2005). Otherwise, the risk factors in male athletes seem to be related mainly to decreased knee flexion (Quatman & Hewett, 2009). Thus, although there are studies demonstrating that males can reduce their injury rates with an injury prevention program (Caraffa, Cerulli, Projetti, Aisa, & Rizzo, 1996; Junge, Rosch, Peterson, Graf-Baumann, & Dvorak, 2002), the differences between sex-related mechanisms of injury lead us to suppose even that certain injury prevention exercises are effective in female populations, there is no guarantee that they will offer the same benefit to similar male populations. Another limitation of previous studies is related to the motor tasks used in the experiments. Researchers tend to use double-leg landings (Irmischer et al., 2004; Myer et al., 2005) to evaluate injury risk, which may also limit the generalisation of results because in some sports, such as volleyball, single-leg landings are common after a jump (Tillman, Hass, Brunt, & Bennett, 2004). In addition, approximately 25% of ACL injuries occur after single-leg landings (Krosshaug et al., 2007). According to DiStefano et al. (2010) the specificity of training should be considered carefully to improve both biomechanics and performance. However, the effect of a preventive training program on the kinematic of different motor tasks is not known. Finally, despite evidence of effectiveness of plyometric training to improve sports performance by increasing VJH, power and agility (Meylan & Malatesta, 2009; Newton et al., 1999; Villareal et al., 2008), as well as the potential effectiveness of PTPs in reducing the risk factors for and incidence of ACL injuries (Irmischer et al., 2004; Myer, Ford, Brent et al., 2006, Myer, Ford, McLean et al., 2006, 2005; Grindstaff, Hamiill, Tuzson, & Hertel, 2006), the degree of influence of PTPs on specific performance variables, such as those listed above, remains unproven. To our knowledge, only one study, by Myer et al. (2005), has evaluated the influence of PTPs in improving sports performance as well as reducing risk factors for ACL injury. The authors demonstrated the efficacy of neuromuscular training in increasing athletic performance and reducing ACL injury risk in female athletes. Kilding, Tunstall, and Kuzmic (2008) and DiStefano et al. (2010) also demonstrated the influence of preventive programs on athletic performance, but they did not examine biomechanical aspects. DiStefano et al. (2010) suggested that future studies should examine performance and lower-limb biomechanical behaviours to identify the effects of PTPs. Therefore, the aim of this study was to examine the effects of a neuromuscular training program on lower-limb kinematics during single-leg and double-leg landings and vertical jump height. The experimental hypotheses were that: (i) the training-related changes would be specific to each landing; (ii) the training program would improve vertical jump height; and (iii) the training program would induce kinematic changes, such as increased knee and hip range of motion.

2. Methods

Fifteen male volleyball athletes from a regional team (age: 13  0.7 years, height: 1.70  0.12 m and body mass 60  12 kg) with no history of lower-limb joint injuries participated in this  study. At the time of the intervention, all the athletes had  at least three years’ experience in the sport and all of them were used to playing in regional and national competitions. A parent/guardian signed informed consent for each athlete and authorised his participation in the study, which was approved by the State University of Rio de Janeiro Ethics Committee. In the week before starting and in the week after finishing training, the subjects underwent tests to examine lower-limb kinematics during landing after vertical jumps and the maximum height reached in these tasks. The training was performed  in the beginning of the season. Two vertical jumps were used to induce the targeted kinematic behaviour. For each sequence, the athletes performed the propulsive phase of jumping twice with both legs, but in one they landed with the dominant leg (SL) and in the other they landed with both legs (DL) (Fig. 1A and B). The dominant leg was defined as the leg the participant would use to kick a ball as far as possible (Myer, Ford, Brent et al., 2006, 2005). Initially, the athletes familiarised themselves with the tasks to reduce the influence of a learning effect on the biomechanical variables. At least 5 min after the familiarisation session, three SL and three DL were filmed in the sagittal plane and stored in a computer for later analysis. A trial was considered successful if the athlete could land without losing balance. No athlete had more than two unsuccessful trials. The landing tasks were performed in a random sequence to minimise the possible effects of fatigue, beginning with SL or DL. A one-minute rest interval was allowed between attempts. The subjects performed all tests and training with the shoes they used to play regularly. The only
instruction provided to the athletes was to jump as high as possible and land in the specific condition (double leg or single leg). The execution of landing tasks was filmed with a camera (Sony DCR HC 46) positioned in the sagittal plane 2 m away from the place of execution, with the optical axis projected onto the centre of the capture area perpendicular to the vertical and horizontal orientations and a sample frequency of 30 Hz, which allowed the interlaced processing of 60 frames per second. Six spherical, 20-mm reflective markers were positioned at each athlete’s iliac crest, greater trocanter, lateral condyle of the femur, lateral malleolus, lateral calcaneus and fifth metatarsal to allow us to examine the angular behaviour of the hip and knee in the sagittal plane (Fig. 2). The metatarsal point was used only to generate the corporal model. To assure marker placement reliability, the same researcher, with great experience in palpatory anatomy, positioned all markers in all subjects. A static trial was collected A static trial was collected by asking the subject to stand still while he was aligned with the laboratory (global) coordinate system. This measurement was used to define each subject’s neutral (zero) alignment, with subsequent dynamic kinematic measures quantified relative to this position. To calibrate the images, four non-collinear points were positioned at the vertices of a 50-cm-sided cube positioned parallel to the capture plane and located in the area where the landing tasks were executed (Robertson & Caldwell, 2004). The data for all subjects were captured in the same environment. Therefore, the devices were not relocated between data collection events. After capture, the images were transferred to a personal computer. The raw coordinates of the markers were transformed into global coordinates (Abdel-Aziz & Karara, 1971, p.1) and processed through the Skill Spector software (Geeware, Version 1.2.4, USA), according to the protocol validated by McLean et al. (2005). They found a high correlation between a single camera 2D and a 3D movement analysis system for inter-subject difference for coronal plane knee kinematics (r: 0.76e0.80). The between day intra-tester reliability of this systemwas measured by Button, van Deursen, and Price (2008). They found an ICC ranging from 0.75 to 0.87 for hip, knee and ankle sagittal plane kinematics. We used a low-pass, fourth order Butterworth filter in the forward and reverse directions to prevent phase distortions, with a cut-off frequency of 6 Hz to smooth the kinematic signal.

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To determine the instant of ground contact, we used a custommade footswitch transducer (FootPress LaBiCoM) set in the sole of the subjects’ shoes in the region of the first metatarsal. When the electrical circuit of the footswitch was triggered, a light-emitting diode (LED) positioned in the camera’s capture field was activated, indicating the presence or absence of ground contact. The signal produced by the footswitch was also used to calculate the time of the flight phase. This variable was used to estimate the maximum vertical height according to the formula 0.5*g*(t/2)2, where g is the acceleration of gravity (9.81 m/s2), and t is the flight phase duration, measured between the instants of loss and resumption of ground contact, according to the strategy validated by Leard et al. (2007). The largest vertical displacement achieved by athletes in three trials was considered the maximum height, as Moir, Shastri, and Connaboy (2008) have demonstrated that this strategy has an excellent reliability level for males (ICC > 0.9) and should be used instead of the arithmetic mean. MATLAB version 6.5 (The Mathworks, USA) was used for signal processing.

2.1. Preventive training program

The frequency of training was three times/week for six weeks, 45e60 min per session. Participants were monitored during training by a team of four or five physical education coaches and students trained to correct execution errors and to facilitate performance improvements, which provided an average of one coach for every three athletes, allowing effective and individualised control of the training process. The training program was implemented in the final half of the competitive season. The PTP used in this study consisted of a compilation of strategies used in previous studies (DiStefano et al., 2010; Grindstaff et al., 2006; Heidt et al., 2000; Hewett, Lindenfeld, Riccobene, & Noyes, 1999; Hewett et al., 1996; Irmischer et al., 2004; Meylan et al., 2009; Myer, Ford, Brent et al., 2006, 2005; Myer, Ford, McLean et al., 2006; Paterno, Myer, Ford, & Hewett, 2004; Pollard, Sigward, Ota, Langford, & Powers, 2006). The exercises aimed to allowa higher degree of specificity between training and volley all performance. Plyometric, balance and core stability exercises were used (Appendix 1 and 2). After each PTP session, the athletes performed their technical training routine. The PTP was divided into three phases according to Hewett et al. (1996): 1) The technique phase, focused mainly on basic aspects such as correct posture, body alignment throughout the jump, soft landings and instant recoil preparation for the subsequent jump; 2) The fundamentals phase, focused on proper technique to increase power and ability and 3) The performance phase, focused on achieving maximal vertical jump height through improved technique. The training programwas modified every two weeks to increase the difficulty of the exercises because the Principle of Overload indicates that a two-week period is long enough to allowathletes to assimilate the difficulties of previous exercises (Hewett et al.,1996). The degree of difficulty was increased through the use of single leg exercises, increased repetitions and intensity and the use of unstable surfaces with eyes open and closed during specific volleyball techniques (dual task). In each session, approximately eight or nine plyometric exercises, four or five core stability exercises and four or five balance exercises were conducted. A 2-min rest interval was allowed between exercises.

2.2. Statistical analysis

The vertical jump height and angular and temporal lower-limb kinematics related to two landing tasks were compared during bilateral vertical jumps (single-leg landings (SL) and double-leg landings (DL)) (Fig. 1A and B) between before and after the application of a preventive training program (PTP). The influence of the PTP was measured in the following variables: vertical jump height (VJH); angular position of the hip and knee upon ground contact after the flight phase (IAPH and IAPK, respectively); angular position of the hip and knee measured when the body’s centre of gravity reached its lowest position of vertical displacement (MAPH and MAPK, respectively); hip and knee range of motion (HRoM and KRoM) from the initial contact to the maximum angle of each joint; and the time of landing (TL), designated as the time, in seconds, from the initial contact to the lowest position of vertical displacement. These biomechanical variables were selected on the basis of studies that proposed a relationship between the behaviour of these variables and ACL injury risk
factors in men (Quatman & Hewett, 2009; Renstrom et al., 2008) and on the relationship between VJH and performance in volleyball players (Barnes et al., 2007). The reliability of all dependent measures among three attempts for each landing task before and after training was determined using the intraclass correlation coefficient (ICC2,1) and standard error of measurement (SEM) (Weir, 2005). To examine the influence of the training programme on the tested variables, the pre-test and post-test values were compared using the Wilcoxon ranked test, with a significance level of 5%. We used a non-parametric test due to the limited sample size and in consideration of the KolmogoroveSmirnov test results, which suggested a non- Gaussian distribution. The statistical analysis was performed using GraphPad Prism, Version 5.00 for Windows (GraphPad Software, San Diego, California, USA).

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3. Results

All individuals completed at least 80% of the training sessions and performed the tests before and after training, with a mean of 89% (16 from 18 total sessions) of compliance. No athlete was injured or had musculoskeletal pain during or after the training period.

3.1. Reliability analysis

The ICC2,1 of the dependent variables achieved in three attempts at each landing before and after training are shown in Table 1. Excellent reliability values (>0.8) were found for all the situations in both landings.

3.2. Vertical jump height

No statistically significant differences were found between the pre- and post-training in relation to the VJH values with SL or DL (Tables 2 and 3). The means, standard errors, confidence intervals and p values of SL and DL, the dependent variables of this study, are presented in Tables 2 and 3, respectively, and described below.

3.3. Single-leg landing

There were no significant differences between training periods for IAPH, IAPK, MAPH, MAPK, HRoM and KRoM. However, after training, athletes showed significantly longer TLs compared to the pre-training period.

3.4. Double-leg landing

There were no significant differences between training periods for IAPH, IAPK, MAPH, MAPK, HRoM and TL. After training, the athletes showed a statistically significant increase in KRoM.

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4. Discussion

Improving the overall athletic performance involves, among others things, acting on several variables specific to each situation, seeking that athletes achieve better performance with a low injury risk. In this context, an important goal of preventive exercise is to develop the ability to perform movements with less aggressive mechanical characteristics. In this study, male volleyball athletes participated in a PTP, and their subsequent performance was examined to determine the PTP’s influence on athletic performance and lower-limb kinematics in two landing tasks with different constraints. To our knowledge, this is the first study to examine the influence of preventive training on both the athletic ability and lower-limb kinematics of young male athletes during different types of landings. Other investigations that have addressed this type of training focused on its influence on women (Myer et al., 2005) or on athletic performance alone in young people of both sexes or just males (DiStefano et al., 2010; Irmischer et al., 2004). As has been already described, the risk factors and mechanisms of injury, although not proved by a prospective study, seem to be different between genders, therefore, the inference of the results obtained from female to male athletes should be done carefully. The results obtained in a previous investigation with the same population (Leporace et al., 2010) showed that the valgus angle of the examined group during landings tasks are regarded as being at low risk for ACL injuries (Hewett, Myer, & Ford, 2004; Schmitz, Kulas, Perrin, Riemann, & Shultz, 2007; Swartz, Decoster, Russell, & Croce, 2005; Yu et al., 2005). Although the knee flexion could be considered low, the adequate alignment in frontal plane may be related to low risk for ACL injury. Myer, Ford, Brent, and Hewett (2007) showed that youths with low susceptibility to this injury are less sensitive to preventive training and have a tendency to make minor biomechanical adaptations to exerciseinduced stimuli. Thus, it was generally expected the subjects in the present study to have a low response to training, which does not imply that this training program does not generate an increase in sports performance or that the results would be similar for both types of landings, which in fact could be confirmed in this study. It was verified for SL that, despite the increase in the angular range of motion of the hip and knee, the training effect on the kinematicswas minimal. This low expression for the angular lowerlimb kinematics during unilateral landing may be partially explained by the characteristics of the chosen exercises of the PTP (Tables 1 and 2). The programs have higher number of bilateral plyometric exercises than unilateral, and the stability exercises required no deep knee flexion and no pronounced anterior trunk displacement. Paterno et al. (2004) used plyometric and stability exercises with backward-forward displacement for 6 weeks, which resulted in improved control of body centre of gravity (CoG) displacement in the anterioreposterior direction, although no improvement in medialelateral control occurred. Louw, Grimmer, and Vaughan (2006), who used a training protocol consisting of unilateral plyometric exercises in a population similar to that of the present study, found significant changes in knee-joint displacement after training. This set of findings highlights the importance of respecting the Principal of Specificity when selecting an exercise training program. It is possible that the athletes presented a greater landing duration after training to compensate for their inability to stabilise the knee-joint in deep flexions during the SL. In general, this strategy may have been adopted to reduce the mechanical loads around a joint, given that with more time, the mechanical impulse generated is more likely to be distributed with lower peak forces, leading to greater absorption of the energy generated by a task.We suggest that exercise programs with longer durations and more specific exercises be conducted to evaluate the kinematic and kinetic adaptations in this population. Regarding the maximum flexion of the hip in DL, although the p value did not reach significance, there was a strong trend (p ¼ 0.0645) and a large effect size (Cohen’s d ¼ 0.83). The mean difference was approximately 10, which resulted in a joint ROM increase of approximately 12 in the post-training (Cohen’s d ¼ 0.78), mainly due to anterior trunk inclination. This kinematic behaviour suggests the CoG moving to coordinates in which it remains horizontally aligned with the axis of knee motion. This indicates decreasing extensor torque in this joint, which also reduces the ACL strain (Blackburn & Padua, 2008). This result may be related to the individual’s increased ability to control the CoG projection over the support basis, which is typically obtained as an effect of neuromuscular training programs (Paterno et al., 2004). The knee movement, regarded as a hip angular behaviour-associated movement, showed a significant difference (p ¼ 0.0371, Cohen’s d ¼ 0.80) of approximately 6 in the flexion displacement, which, according to Blackburn and Padua (2008), corroborates the ACL tension reduction. However, this alteration was probably due to the decrease in the knee flexion at initial contact, which may actually increase injury risk (Hewett et al., 2005; Quatman & Hewett, 2009). Future studies are needed to discuss the effect of the paradigm related to the increase of knee displacement as a result of decreased knee flexion at initial contact. Although other studies have suggested that neuromuscular training induces changes in athletic performance (Bobbert, 1990; Kilding et al., 2008; Myer et al., 2005; Villareal et al., 2008), we found no statistically significant difference when comparing pre- and post-training, either for SL or DL. It is possible that 6 weeks of neuromuscular training is insufficient to produce changes in these sports performance aspects in young male athletes. However, previous studies have reported that increases of approximately 10% in jump height with countermovement are associated with improvements in sports performance (Bobert, 1990; Markovic, 2007; Villareal et al., 2008). In this study, based on the evaluation of differences in preand post-training absolute values and on the medium effect size (Cohen’s d ¼ 0.52), we observed that improvements, although not statistically significant, in both landings types were compatible and, in some cases, even higher than the values that were associated in the literature with a positive impact on athletic performance. Villareal et al. (2008) demonstrated in a meta-analysis that plyometric training programs generally generate increases of approximately 7%, corresponding to 3.9 cm in jump height after about 10 weeks. Regarding the preventive programs, Myer et al. (2005) showed improvements of about 3.3 cm (8.3%) after six weeks of training; Kilding et al. (2008) reported improvements of 2 cm (6%) and Di Stefano et al. (2010) reported 1.7-cm improvements (6.9%) after nine weeks of training. The present study found differences of 2.7 cm (10%) and 3.5 cm (11.3%) for the vertical jumps with SL and DL landings, respectively. Despite the absence of statistical differences in the pre- and post-training values, the training program employed in this study increased the athletic performance of young male volleyball athletes in a way similar to that reported in the literature after a training period of only 6 weeks. Moreover, as described earlier the PTP was implemented in the final half of the season. The focus of the training at this stage was on tactical aspects of volleyball while technical aspects related to performance variables were already finished. This emphasizes the importance of implementation of PTP despite the cycle of periodization of the training seeking also performance improvement. The duration of neuromuscular training seems to be a decisive factor, given the significant changes in the young athletes’ performance. Thus, further studies using longer training periods are encouraged to determine the course of the changes in athletic performance over time and establish the minimum period necessary to achieve changes in biomechanical behaviours associated with performance improvements at different stages of training. Unlike other explanations presented in the literature, it can be suggested that the lack of statistical differences for performance in the vertical jump height could be associated with the research design. The majority of previous studies used pre-post-test differences to compare the training effect between intervention and control groups (DiStefano et al., 2010; Kilding et al., 2008; Myer et al., 2005). In contrast, this study adopted the strategy of matching samples. It is suggested the implementation of randomized controlled trials to test the hypothesis of an increase of vertical jump height after the performance of PTPs. Another interesting finding of this study is related to the reliability of the jump height in the three attempts with both landing conditions. Although the findings for the DL jump support the literature (Moir et al., 2008), no studies have examined the reliability of DL vertical jumps with successive SL landing, which is common in volleyball practice (Tillman et al., 2004). In this sense, our results suggest that both landing forms started from jumps of bilateral propulsion can be employed in training programs to evaluate maximal jump height, due to the high reliability value found. Although much of our findings obtained in this investigation are consistent with the literature, three facts must be re-examined carefully. One, which is a limitation of this study, concerns the training time used. Because of technical staff planning and the sports calendar, it was only possible to apply the preventative training for a sixeweek period. Although several studies intending to change movement patterns related to ACL injury risk have used a same time interval, the literature recommends that training programs with PTP features should be conducted throughout the sports season with adequate periodization (Grindstaff et al., 2006).  The second aspect is related to the absence of a control group. Thus, it is unclear whether the observed improvements are due to the results of the applied training or other, uncontrolled factors. Additional, controlled studies aimed at measuring the effect of neuromuscular training on lower-limb kinematics and kinetics after different periods of practice are recommended to determine the time required to obtain increased training efficiency without causing excessive stress on joints. The third aspect is related to the possible clinical significance of the results. Despite the present study’s values for the angular variables and height of jumps changes, alterations presented by athletes suggest that the exercise program employed has a mechano-inductive capacity, even in limited magnitude. However, it was also possible to verify that the exercises tended to induce more important developments in a type of landing that corroborates with the proposition that the biomechanical changes in different motor behaviours after a neuromuscular training program are specific to a given stimuli (DiStefano et al., 2010; Myer, Ford, McLean et al., 2006; Myer et al., 2005). Thus, a training program can be effective in inducing changes in motor behaviour related to preventing the incidence of ACL injuries and athletic performance in one motor conduct and not for another.

5. Conclusion

The PTP seems to induce changes to the kinematic behaviour of the lower limbs. In the single leg condition, the time of landing was increased, while in the double leg condition the knee range of motion was improved. This highlights the importance of the selection of the tasks used to compare the kinematics of lower limbs. Also, although the vertical jump height was not statistically different, the improvement of 10% in both jumps tasks agrees with the values described in the literature and is an important performance improvement in volleyball. Therefore, the results allow us to conclude that PTP may induce specific changes on lower limbs kinematics and improve variables related to sport performance. This supports the idea that training programs similar to the one used in this study should be used in sports; however, they must be applied for longer periods, with adequate periodization during the season.

Conflict of interest
None declared.

Ethical approval
This studywas approved by the State University of Rio de Janeiro Ethics Committee.

Funding
This study was partially supported by the Brazilian Research Council (CNPq), Carlos Chagas Filho Foundation for Research Support of Rio de Janeiro (FAPERJ) and Coordination for the Improvement of Higher Level Education (CAPES).

Leia o artigo completo: https://www.ncbi.nlm.nih.gov/pubmed/23312730