Acute effects of Nordic hamstring exercise on hip and knee joints proprioception.

BACKGROUND AND OBJECTIVES: Nordic Hamstring Exercise (NHE) is one of the best exercises proposed for injury prevention of hamstring muscles. However, its effects on lower extremity proprioception are unclear. The aim of this study was to investigate the immediate effects of a single bout of NHE on hip and knee joints' proprioception. METHODS: Forty collegiate male soccer players participated in this study with a mean age of 22.85 ± 1.82 years and were randomized into either control (n = 20) or experimental (n = 20) groups. Each subject participated in pre-test measurements in which hip and knee active joints position sense (JPS) were assessed in standing and lying tasks using the image-capturing method. The experimental group then performed three sets of NHE with 10 repetitions in each set, while the control group rested for 10 min. Paired and independent t-tests were used for calculating the differences within and between groups on SPSS software, respectively. The level of significance was P ≤ 0.05. RESULTS: Hip JPS in the lying task and knee JPS in both of the standing and lying tasks were impaired significantly after performing a single bout of NHE (P ≤ 0.05). However, the effects of this exercise on hip JPS in the standing task were not significant (P ≥ 0.05). CONCLUSIONS: NHE performing with three sets of 10 repetitions can significantly impair hip and knee JPS immediately after exercise and reduce the proprioception acuity of the lower limbs. It is recommended to perform this exercise at a time rather than before training or match sessions.

Electromyography of shoulder muscles in individuals without scapular dyskinesis during closed kinetic chain exercises on stable and unstable surfaces: a systematic review and meta-analysis.

Introduction: Unstable surfaces are commonly utilized to enhance the flexibility of the musculoskeletal system for achieving training or rehabilitation goals. However, their effects on shoulder muscle activation during various push-up (PU) exercises have not been thoroughly investigated. Therefore, the purpose of this study was to synthesize electromyography (EMG) data of shoulder muscles in individuals without scapular dyskinesis performing different PU exercises on both stable and unstable surfaces. Methods: A systematic online search was conducted in electronic databases, including Web of Science, PubMed, Scopus, and Google Scholar, up to January 16, 2024, using predefined sets of keywords. Out of the 1,971 titles and abstracts screened, 80 articles were reviewed in detail by two independent researchers to check the eligibility, of which 28 eligible studies were ultimately included. Following assessment of the quality and risk of bias, the studies were categorized based on exercises and muscle groups, and a meta-analysis using a random-effects model was performed to estimate the overall effect size. Results: The use of unstable surfaces led to a decrease in anterior deltoid activity during PU [P = 0.032; I2 = 91.34%; SMD = -0.630 (95% CI -1.205, -0.055)], an increase in pectoralis major activity during PU [P = 0.006; I2 = 63.72%; SMD = 0.282 (95% CI 0.079, 0.484)], as well as during knee PU [P = 0.018; I2 = 32.29%; SMD = 0.309 (95% CI 0.052, 0.565)], and an increase in triceps brachii activity during PU [P = 0.000; I2 = 85.05%; SMD = 0.813 (95% CI 0.457, 1.168)], knee PU [P = 0.000; I2 = 0.00%; SMD = 0.589 (95% CI 0.288, 0.891)], as well as during push-up plus [P = 0.006; I2 = 13.16%; SMD = 0.563 (95% CI 0.161, 0.965)]. However, the use of unstable surfaces did not show a significant effect on the EMG activity of the pectoralis major during push-up plus [P = 0.312; I2 = 22.82%; SMD = 0.207 (95% CI -0.194, 0.609)]. Conclusions: Unstable surfaces can modulate muscle activity in different PU exercises, while the effects on the targeted muscles depend on the type of exercise. The findings of this review provide a framework based on the level of activity of each shoulder muscle during different PU exercises, which can help coaches, trainers, and sports therapists select the most suitable type of PU for designing training or rehabilitation programs. Particularly, the most suitable exercise for increasing anterior deltoid activity is PU on a stable surface. To concurrently increase activity of the pectoralis major and triceps brachii, adding unstable surfaces under hands during knee PU and standard PU is recommended. Systematic Review Registration: PROSPERO, identifier CRD42021268465.

Core Stabilization Exercises vs. Schroth's Three Dimensional Exercises to Treat Adolescent Idiopathic Scoliosis: A Systematic Review.

Background: Adolescent idiopathic scoliosis (AIS) is one of the most prevalent spinal abnormalities, appearing far into puberty. Schroth's exercises (SE) and core-stabilization exercises (CE) have become very prominent among the specialized and general methods to scoliosis treatment. However, their effects are still unclear and there is insufficient evidence of superiority between them. Therefore, we aimed to evaluate and compare the effectiveness of these methods on Cobb angles (CA) in AIS. Methods: A systematic review was performed on SE and CE papers. The databases included PubMed, Scopus, MEDLINE, Cochrane Library, CINAHL, and Google Scholar from January 2005 to June 2022. The physiotherapy evidence database (PEDro) scale assessed the quality and provided internal validity and the statistical information of the papers. Results: After screening 410 papers, nine papers (SE=5, CE=3 and SE vs. CE=1), with 339 participants, were admitted for review (PEDro=6). Among them, three (SE=moderate evidence) and two papers (CE=limited evidence) reported clinically significant reductions in CA>5°, alone or compared to control or other exercise methods, while only one paper (very limited evidence) showed the relative superiority of SE (-7.16°) compared to CE (-3.27°). However, three papers did not show clinically significant results (CA<5°). Conclusion: Moderate and limited evidence suggests that both SE and CE can effectively improve CA, respectively. There is very limited evidence to suggest that SE is more effective than CE in treating AIS. Thus, the definitive answers to the questions, especially concerning the superiority between these two methods, remained unclear. Further high-quality studies must be conducted in the future.

A systematic review of validity and reliability assessment of measuring balance and walking at the level of International Classification of Functioning, Disability and Health (ICF) in people with spinal cord injury.

Context: A spinal cord injury (SCI) is associated with a wide range of impairments in functioning, many limitations in activity, and restrictions for patients.Objectives: The present study aimed to systematically review the psychometric properties (reliability and validity) of outcome measures used to assess walking and balance in people with spinal cord injury.Methods: Databases such as PubMed, Embase, Scopus, and Web of Sciences were searched for relevant articles using various terms (title and abstract). Articles including the outcome measures of spinal cord injury patients and published in English from 2010 until 2021 were selected, and the quality of the selected studies was determined by applying the COSMIN checklist. Reliability and validity values were extracted, and conclusions were drawn about the psychometric quality of each measure.Results: A total of 1253 records were retrieved, and among them 22 potentially eligible articles were identified, 15 of which were included in the present study. The COSMIN tool (Consensus-based Standards for the selection of health status Measurement Instruments) was used to evaluate the quality level of imported articles based on the inclusion criteria.Conclusions: One consideration for testing people with disabilities is to observe the reliability and validity of the instrument, which was addressed in this study in various fields. In our study, seven tools for assessing SCI were evaluated, and it was found that the 10-meter walk (10MWT) tool performs better and more easily than other tools. The Mini-BESTest tool was suggested as a reliable tool for assessing standing balance in SCI subjects.

The effectiveness of fatigue on repositioning sense of lower extremities: systematic review and meta-analysis.

INTRODUCTION: An injury can significantly harm both individual and team performance. One of the most important risk factors for sports-related injuries, especially non-collision injuries, is fatigue. It seems that poor proprioception may play an essential role to impose athletes to further injuries. This systematic review and meta-analysis aimed to examine the effectiveness of fatigue on the repositioning sense of the lower extremity joints. METHOD: The electronic databases, including PubMed, Web of Science, Scopus, and Google Scholar were systematically searched from inception to 11January 2024. The obtained records were exported to the EndNote Software version 8. Then, two investigators examined the records independently to find eligible studies based on the inclusion/exclusion criteria. In the case of disagreements, a consequence method was utilized. The quality of the eligible studies was evaluated using the Downs and Black checklist. Comprehensive Meta-Analysis (CMA) software ver. 3 software was used for statistical analysis. Q-test and I2 were employed to examine the data homogeneity. In addition, considering the risk of bias, the Funnel Plot and trim-and-fill method were used. RESULTS: After reviewing the titles and abstracts of 3883 studies found in the selected databases, 43 articles were found to be eligible to include in meta-analyses. The results showed that fatigue led to a significant increase in the active absolute error of the knee (SDM = 0.524, 95% CI = 0.406-0.841), ankle in the horizontal plane (SDM = 0.541, 95% CI = 0.367-0.715), ankle in the sagittal plane (SDM = 0.443, 95% CI = 0.088-0.798), and hip (SDM = 0.988, 95% CI = 0.135-1.841). However, fatigue had no significant effects on the passive absolute error of the knee and ankle in horizontal plane and relative angular error of the knee. CONCLUSION: Fatigue can diminish the active joint position sense of the lower extremities and thus may increase the risk of injury by reducing proprioception. Therefore, future research could be conducted to investigate the potential impact of integrated fatigue-mitigating exercises into athletes' training programs, with the aim of reducing the incidence of sports-related injuries.

Outcomes of 12 Weeks of Schroth and Asymmetric Spinal Stabilization Exercises on Cobb Angle, Angle of Trunk Rotation, and Quality of Life in Adolescent Boys with Idiopathic Scoliosis: A Randomized-controlled Trial.

Objectives: The available evidence on the efficiency of well-known Schroth's exercises (SE) for correcting adolescent idiopathic scoliosis (AIS) is limited, especially in combination with the asymmetric spinal stabilization exercises (ASSE) method. Therefore, we hypothesized that, first, there is no difference in the efficiency of the combined exercises (SE+ASSE) and SE alone in improving Cobb angle, angle of trunk rotation (ATR), and quality of life (QoL) in AIS. Second, there is no difference in the efficiency of SE and no intervention on corresponding variables in treating AIS. Methods: This randomized controlled trial (RCT) consisted of 40 patients with mild AIS (10-18-year-old boys) divided into three groups: SE (n=15), SE+ASSE (n=15), and a waitlist control group (n=10). For 12 weeks (three days a week), both experimental groups performed SE, the combined group additionally received ASSE, and the control group received no intervention. The assessment included Cobb angle (photogrammetry), ATR (Adam's test), and QoL (Scoliosis Research Society-22 questionnaire). Results: It was found that Cobb angle, ATR, and QoL improved significantly in the combined SE+ASSE group (Cobb=16.45° to 9.01°; ATR=4.93° to 1.33°) compared to the SE group (P<.001). In addition, the SE group showed significant amelioration in the mentioned variables (Cobb=15.09° to 9.77°; ATR=4.23° to 2.17°) compared to the control group (P<.001), whereas the control group remained almost unchanged. Conclusion: Based on the obtained results, the combination of SE and ASSE provided more benefits than SE alone, and the SE results were efficient compared to the no-intervention group regarding the correction of scoliosis and related problems. However, patients with moderate to severe scoliosis should also be investigated in longer treatment periods in future.

Knee Biomechanics During Neurocognitively Challenged Drop Landings in Male Elite Soccer Players with Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Reactive decision-making during athletic movement has been demonstrated to evoke unfavorable biomechanics associated with anterior cruciate ligament (ACL) rupture. However, the current evidence is based on assessments of healthy individuals. We aimed to investigate unplanned jump landing kinetics and knee kinematics in ACL-reconstructed (ACLR) and non-injured athletes. METHODS: A total of 30 male professional soccer players (n = 15 ACLR after return to play, n = 15 matched controls) performed six drop landings onto a force plate. As a neurocognitive challenge requiring decision-making, a diode flashing in randomly selected colors indicated the requested landing location. Knee joint kinematics (flexion, valgus and tibial rotation angles) assessed with a 10-camera motion capture system, vertical ground reaction force (vGRF), time to stabilization (TTS) and length of the center of pressure (COP) trace (all analyzed from force plate data) were calculated. Cognitive function was assessed using the CNS Vital Signs battery. RESULTS: The ACLR group produced lower knee flexion angles than the control group (median [interquartile range] 50.00° [6.60] vs. 55.20° [4.45], p = .02). In addition, path length of the center of pressure (379 mm [56.20] vs. 344 mm [37.00], p = .04) and ground reaction force (3.21 N/kg [0.66] vs. 2.87 N/kg [0.48], p = .01) were higher for the ACLR group. No differences were found for knee valgus (p = .96), tibial rotation (p = .83) and TTS (p = .82). ACLR participants scored lower for reaction time (p = .02) and processing speed (p = .01). Unfavorable knee biomechanics were more often related to cognitive function in the ACLR group than in the control group (p < .05). CONCLUSIONS: Impaired reactive decision-making during athletic movement may contribute to the high re-injury risk in individuals with ACLR. Prospective studies confirming potential cause-effect relationships are warranted.

Effects of biofeedback on biomechanical factors associated with chronic ankle instability: a systematic review with meta-analysis.

BACKGROUND: Biofeedback may alter the biomechanics of lower extremities in patients with chronic ankle instability (CAI). We aimed to systematically review the literature on the effect of gait-training and biofeedback on biomechanical parameters in individuals with CAI and conduct a meta-analysis. METHODS: We searched four databases including PubMed, Web of Science, Scopus and Embase from their inception through 30th June 2022. The Downs and Black appraisal scale was applied to assess quality of included studies. Two reviewers screened studies to identify those reporting the effect of biofeedback on biomechanical factors associated with CAI. Outcomes of interest were kinetics and kinematics. Two authors separately extracted data from included studies. Data of interest were study design, number of sessions, intervention, tools, outcomes, number, sex, age, height, and body mass of participants. RESULTS: Thirteen studies with a total of 226 participants were included. Biofeedback was capable of shifting center of pressure (COP) and lateral plantar pressure medially and reducing foot inversion, adduction, propulsive vertical ground reaction force (vGRF), ankle joint contact force, peak pressure and pressure time integral in the lateral mid-foot and forefoot. Auditory biofeedback had agreater impact on modifying plantar pressure in individuals with CAI. The meta-analyses revealed that visual biofeedback reduces peak pressure in lateral mid-foot and pressure time integral at lateral and medial heel and pressure increases under the hallux. CONCLUSION: Biofeedback can alter pressure, vGRF, and foot inversion associated with CAI. Auditory biofeedback had greater impact on modifying plantar pressure in individuals with CAI. Further studies are required to assess the prolonged effect and clinical consequences of biofeedback or a combination of feedback on CAI in different age groups. Moreover, developing a low-cost and user-friendly device that can be evaluated in high quality RCTs is important prior to implementing the intervention in the clinical setting to reduce symptoms of CAI.

Electromyography of scapular stabilizers in people without scapular dyskinesis during push-ups: a systematic review and meta-analysis.

Background: Push-up (PU) is widely considered an effective exercise to stabilize the scapular, especially if performed on unstable surfaces. However, available studies cover a wide range of exercise variations and differ according to exercise prescription, muscle selection and study design. Therefore, findings are contradictory, and conclusions for a proper application of the PU are difficult to draw. Objective: To synthesize the available literature on the changes in the activity of the periscapular muscles in individuals without scapular dyskinesis while performing different types of PU on unstable surfaces. Search procedure: Four online databases were searched from the earliest publications to 9 August 2023, using predefined keywords. Out of the 2,850 potential references identified in the primary search, 92 studies were reviewed in detail, of which 38 met the inclusion criteria and were included. Methodological quality was evaluated using a standardized form based on the Newcastle‒Ottawa scale for observational studies. Data combination was performed using CMA (v3), and the random-effects model was used to calculate the standardized mean difference (SMD) with a 95% confidence interval (CI). Results: The use of unstable surfaces in people without scapular dyskinesis led to increased activity of the upper trapezius during the PU (p = 0.017; I2 = 84.95%; SMD = 0.425 [95% CI 0.077, 0.773]) and knee PU (p = 0.023; I2 = 70.23%; SMD = 0.474 [95% CI 0.066, 0.882]) exercises and increased activity of the middle trapezius (MT) (p = 0.003; I2 = 64.50%; SMD = 0.672 [95% CI 0.225, 1.119]) and serratus anterior (SA) (p = 0.039; I2 = 4.25%; SMD = 0.216 [95% CI 0.011, 0.420]) muscles during the push-up plus (PUP) exercise. Conclusion: Using an unstable support base during PU does not necessarily increase the activity of all scapular stabilizers. The amount of muscle activity depends on the type of PU other than the type of support base. If an unstable surface is used, PUP exercise appears to be the most effective modality to increase the quality of training, improve performance, and prevent the occurrence of scapular dyskinesis due to the increase in the activity of the MT and SA muscles. Systematic Review Registration: http://www.crd.york.ac.uk/PROSPERO, CRD42021268465.

Translation and psychometric evaluation of the Persian version of Knee Outcome Survey-Activities of Daily Living Scale (KOS-ADLS).

BACKGROUND: The present study aimed to translate and validate the Knee Outcome Survey-Activities of Daily Living Scale (KOS-ADLS) in Iran. METHODS: Following standard forward and backward translation procedure, content and face validity were tested by specialists and a sample of 32 patients. Then, in a cross sectional study, a sample of patients with knee disorders, recruited through simple sampling, completed the KOS-ADLS and the Short-Form Health Survey (SF-36) in their first visit to physiotherapy clinics in Tehran. Regarding construct validity, the Spearman's correlation (rs) and one-way ANOVA were employed to evaluate the correlations between the Persian KOS-ADLS and SF-36 subscales (convergent validity) and known groups comparison, respectively. Test-retest reliability and internal consistency were evaluated by intraclass correlation coefficient (ICC) and the Cronbach's α coefficient. RESULTS: In total 101 patients were included in the study. The mean age of patients was 42.39 (SD = 9.2). The finding indicated that the KOS-ADLS had strong correlations with SF-36 physical functioning, bodily pain subscales, and also physical component summary while it had lower correlations with other subscales of the SF-36 as expected. The KOS-ADLS was able to differentiate between the subgroups of patients who differed in BMI. The acceptable level of intraclass correlation coefficient (ICC = 0.91) and Cronbach's α coefficient (α = 0.91) was obtained for the Persian KOS-ADLS. Also no floor and ceiling effects were observed for the questionnaire. CONCLUSIONS: The Persian version of KOS-ADLS was found to be a reliable and valid outcome measure for assessing daily living activities in patients who suffer from knee pathological conditions.

Prevalence of idiopathic scoliosis in athletes: a systematic review and meta-analysis.

Objective: This study aimed to determine the prevalence of idiopathic scoliosis (IS) in child, adolescent and adult athletes of all sports activity levels. Design: Systematic review with meta-analysis. Data sources: Electronic databases (PubMed, Scopus, ProQuest, Sage journals, ScienceDirect, Google Scholar and Springer) were systematically searched up from inception to 28 September 2021. Eligibility criteria for selecting studies: Observational investigations were included to evaluate the prevalence of IS in athletes (engaged in any type of individual and team sports). Congenital scoliosis, neuromuscular scoliosis, Scheuermann's kyphosis and de novo scoliosis were not included. The risk of bias was assessed using the tool developed by Hoy et al. Results: Twenty-two studies were included (N=57 470, range 15-46544, participants), thirteen studies were of high-quality. The estimated prevalence of IS in athletes was 27% (95% CI 20% to 35%, I2=98%), with a 95% prediction interval (1% to 69%). The prevalence of IS was significantly higher in female athletes (35%, 95% CI 27% to 34%, I2=98%). Ballet dancers showed a high IS prevalence (35%, 95% CI 24% to 47%, I2=98%). Recreational athletes showed a higher IS prevalence (33%, 95% CI 24% to 43%, I2=98%) than at competitive-level athletes (0.05%, 95% CI 0.03% to 0.08%, I2=98%), followed by elite (20%, 95% CI 13% to 27%, I2=98%). Conclusions: The prevalence of IS in athletes was similar or higher to that as seen in other studies of the general population. IS prevalence may have a U-shaped relationship relative to level of competition. Further studies are required to determine which sports have the highest IS prevalence.

Higher Leg and Trunk Muscle Activation during Balance Control in Copers versus People with Chronic Ankle Instability and Healthy Female Athletes.

More than 70% of people with ankle sprain experience chronic ankle instability. However, some people are well adapted to this damage (copers) and do not suffer from chronic ankle instability (CAI). This cross-sectional study involved 34 female athletes, who were classified into three groups (athletes with CAI, copers, and healthy athletes) and tested on a Biodex Balance System. Surface electromyography (EMG) and balance scores were monitored. The coper and healthy group exhibited higher medial gastrocnemius (MG) EMG activity during unstable balance conditions. The rectus abdominus (RA) in the coper group and rectus femoris (RF) in the healthy group showed greater EMG activity compared to CAI during unstable conditions. During stable conditions, the coper group showed greater RA EMG activity compared to CAI, as well as higher tibialis anterior (TA) EMG activity compared to the healthy group. Additionally, balance error scores were higher in the CAI group than those in the healthy group under unstable conditions. In conclusion, decreased EMG activity of the MG, RF, and RA in CAI athletes may contribute to impaired balance in these individuals. The increased EMG activity of the MG, TA, and RA in copers might result in more trunk and ankle stability.

The effectiveness of the comprehensive corrective exercise program on kinematics and strength of lower extremities in males with dynamic knee valgus: a parallel-group randomized wait-list controlled trial.

BACKGROUND: Dynamic knee valgus (DKV) is a prevalent movement impairment widely regarded as a risk factor for lower extremity disorders such as patellofemoral pain syndrome. The present study aimed to investigate the effectiveness of the comprehensive corrective exercise program (CCEP) on kinematics and strength of lower extremities in males with DKV. METHODS: Thirty asymptomatic young men with DKV between the ages of 18 and 28 years participated in this study. They were randomly assigned to the intervention (n = 15) and control groups (n = 15). The intervention group performed the CCEP for three sessions per week for eight weeks, while the control group only did activities of daily living. Hip external rotator and abductor muscle strength and three-dimensional lower extremity kinematics consisting of knee varus/valgus, femur adduction/abduction, femur medial/lateral rotation, and tibial medial/lateral rotation were measured at the baseline and post-test. The data were analyzed using the analysis of covariance (ANCOVA). RESULTS: There were significant improvements in all kinematics variables in the intervention group after the 8-week CCEP. Moreover, the strength of abductor and external rotator muscle improved in the intervention group (P < 0.05). CONCLUSIONS: The CCEP led to substantial improvements in the selected variables of lower extremity kinematics and muscle strength in participants with DKV during a single-leg squat. These results imply that practitioners should adopt a comprehensive approach to pay simultaneous attention to both proximal and distal segments for improving DKV. TRIAL REGISTRATION: The protocol has been approved in the Registry of Clinical Trials (Registration N: IRCT20180821040843N1 ) on 2018-12-30.

What are gender differences in lower limb muscle activity during jump-landing tasks? A systematic review and meta-analysis.

BACKGROUND: Gender differences in muscle activity during landing have been proposed as a possible contributing factor to the greater incidence of anterior cruciate ligament injuries in women. Conflicting results among a few studies in this regard makes it impossible to reach correct conclusions. OBJECTIVES: The aim of this study was systematic review and the meta-analysis of previous studies which have compared the electromyographic activity of lower limb muscles in gluteus muscles (maximus and medius), quadriceps (rectus femoris, vastus medialis and lateralis), hamstrings (biceps femoris and semimembranosus), and gastrocnemius in men and women in jump-landing task. METHODS: A systematic search of the PubMed, SCOPUS, Science Direct databases was performed for eligible articles in October 2020. Cross-sectional studies that compared the muscle activity of male and female athletes without a history of previous injury in the jump-landing task were included. Unisex and non-athlete's studies were extracted from the included studies. The data were synthesized using a fixed and random effects model. RESULTS: Eight studies involving 145 participants were included. All participants were people who participated in regular exercises. The meta-analysis of timing and muscle activity was performed in the feedforward (pre contact) and feedback (post contact) stages. There were no significant differences in the muscle activity of biceps femoris (MD = -12.01; 95% CI - 51.49 to 27.47; p = 0.55; I2 = 87%), vastus medialis (MD = -53.46; 95% CI - 129.73 to 22.81; p = 0.17; I2 = 91%), semimembranosus (MD = 1.81; 95% CI - 6.44 to 10.07; p = 0.67; I2 = 0%), gluteus medius (MD = -3.14; 95% CI - 14.24 to 7.96; p = 0.58; I2 = 48%), and rectus femoris (MD = -5.83; 95% CI - 14.57 to 2.92; p = 0.19; I2 = 87%) in the pre contact phase between two sexes. There was a significant difference between men and women in the activity of vastus lateralis muscle in the post contact phase (MD = -34.90; 95% CI - 48.23 to - 21.57). No significant difference was observed between the men and women in the timing of semimembranosus (MD = 23.53; 95% CI - 14.49 to 61.54; p = 0.23; I2 = 56%) and biceps femoris muscle activity (MD = -46.84; 95% CI - 97.50 to 3.83; p = 0.07; I2 = 82%). CONCLUSION: The results showed that in all lower limb muscles except vastus lateralis there were no significant differences between muscle activity and muscle contraction timing in both sexes before and after foot contact. Therefore, it can be concluded that the reason for the greater susceptibility of ACL injuries in women than men is maybe related to other factors such as biomechanical and hormonal. Additional good quality research in this regard is required to strengthen these conclusions.

The Effects of a Self-Myofascial Release Program on Isokinetic Hamstrings-to-Quadriceps Strength Ratio and Range of Motion of the Knee Joint Among Athletes With Hamstring Shortness.

CONTEXT: Range of motion (ROM) and muscular strength are the main factors that affect athletic performance. Self-myofascial release is a flexibility technique, which is used to inhibit overactive muscle fibers. OBJECTIVE: To investigate the effects of the 8-week self-myofascial release on the isokinetic hamstrings-to-quadriceps strength ratio (H/QRatio) and the ROM of the knee joint among male athletes with the hamstring shortness. DESIGN: A randomized controlled trial. SETTING: Research laboratory. PARTICIPANTS: Twenty-four college-aged male athletes with hamstring shortness were selected for this study and were randomly assigned to a foam rolling group (FOAM, n = 12) and a control group (n = 12). INTERVENTIONS: Participants in the FOAM group performed supervised self-myofascial release program 3 times per week for 8 weeks. The control group received no intervention. METHODS: Data were analyzed via 2-way repeated-measure analysis of variance at the significance level of .05. MAIN OUTCOME MEASURES: ROM and the H/QRatio at the velocities of 60°/s, 120°/s, and 180°/s were measured by an isokinetic dynamometer. RESULTS: The results of 2-way repeated-measure analysis of variance demonstrated that hamstring ROM increased in FOAM group (P = .001). No significant changes were found in H/QRatio after self-myofascial release for FOAM group (P ≥ .05). CONCLUSIONS: When compared with other methods of stretching, self-myofascial release with foam rolling may be beneficial in increasing ROM without decreasing H/QRatio in people with the hamstring shortness.

Can lower extremity anatomical measures and core stability predict dynamic knee valgus in young men?

INTRODUCTION: Dynamic knee valgus (DKV) is a risk factor for lower extremity injuries such as anterior cruciate ligament and patellofemoral pain syndrome. Purpose of the current study was to investigate the relationship between lower extremity anatomical measures (LEAM) and core stability with DKV during the single-leg squat. METHODS: Thirty healthy men aged between 18 and 28 years participated in this cross-sectional biomechanical study.DKV was assessed using a 6-camera motion analysis system during a single-leg squat task. Anteversion of hip, hip internal and external rotation, Q-angle, knee hyperextension, tibial torsion, tibia vara, plantar arch index, and core stability were measured using standard clinical procedures. To predict DKV, a multiple linear regression model was used. RESULT: The stability index negatively and plantar arch index positively predicted greater DKV during the single-leg squat task (P = 0.001 and P = 0.09, respectively). Research variables together predicted 82% of the variance in DKV (F(4,26) = 28.09, p < 0.001). However, relationships between other variables and DKV were not found. CONCLUSION: The core stability index and plantar arch index were associated with observed DKV during the single-leg squat. These results suggested that proximal and distal variables to the knee should be considered when evaluating individuals who present DKV during the single-leg squat.

Factors Associated With Lower Limb Injuries in Recreational Runners: A Cross-Sectional Survey Including Mental Aspects and Sleep Quality.

Knowledge about prevalence and etiology of running-related injuries (RRIs) is important to design effective RRI prevention programs. Mental aspects and sleep quality seem to be important potential risk factors, yet their association with RRIs needs to be elucidated. The aims of this study are to investigate the epidemiology of RRIs in recreational runners and the association of mental aspects, sleep, and other potential factors with RRIs. An internet-based questionnaire was sent to recreational runners recruited through social media, asking for personal and training characteristics, mental aspects (obsessive passion, motivation to exercise), sleep quality, perceived health, quality of life, foot arch type, and RRIs over the past six months. Data were analyzed descriptively and using logistic regression. Self-reported data from 804 questionnaires were analyzed. Twenty-five potential risk factors for RRIs were investigated. 54% of runners reported at least one RRI. The knee was the most-affected location (45%), followed by the lower leg (19%). Patellofemoral pain syndrome was the most-reported injury (20%), followed by medial tibial stress syndrome (17%). Obsessive passionate attitude (odds ratio (OR):1.35; 95% confidence interval (CI):1.18-1.54), motivation to exercise (OR:1.09; CI:1.03-1.15), and sleep quality (OR:1.23; CI:1.15-1.31) were associated with RRIs, as were perceived health (OR:0.96; CI:0.94-0.97), running over 20 km/week (OR:1.58; CI:1.04-2.42), overweight (OR:2.17; CI:1.41-3.34), pes planus (OR:1.80; CI:1.12-2.88), hard-surface running (OR:1.37; CI:1.17-1.59), running company (OR:1.65; CI:1.16-2.35), and following a training program (OR:1.51; CI:1.09-2.10). These factors together explained 30% of the variance in RRIs. A separate regression analysis showed that mental aspects and sleep quality explain 15% of the variance in RRIs. The association of mental aspects and sleep quality with RRIs adds new insights into the multifactorial etiology of RRIs. We therefore recommend that besides common risk factors for RRI, mental aspects and sleep be incorporated into the advice on prevention and management of RRIs.

Electromyographic analysis in elite swimmers with shoulder pain during a functional task.

The purpose of study was to determine and compare electromyographic activity of selected shoulder girdle muscles in elite swimmers with and without shoulder pain. Twelve professional swimmers with shoulder pain (mean age: 18.55 ± 3.16 years, body mass: 74.33 ± 2.91 kg and height: 179.00 ± 5.29 cm) and 12 swimmers without pain (mean age: 18.11 ± 1.61 years, body weight: 73.33 ± 6.06 kg, height: 178.33 ± 5.07 cm) were recruited. Surface electromyography signals were collected from seven upper limb muscles during a task: participants were instructed to mark points with a pen within each of the three circles counterclockwise. The normalised root-mean-square value was used to determine the muscular activation. Swimmers with shoulder pain demonstrated greater activation of the upper trapezius (pain group mean: 28.04 ± 10.37, control group mean: 13.40 ± 06.04; p = 0.002, ηp2: 0.455), serratus anterior (pain group mean: 30.78 ± 20.09, control group mean: 13.30 ± 5.52; p = 0.023, ηp2: 0.283) and latissimus dorsi (pain group mean: 27.05 ± 17.87, control group mean: 4.99 ± 3.90; p = 0.002, ηp2 : 0.450) muscles. There was no difference (p > 0.05) in the activation of the middle and lower trapezius, middle deltoid and sternocleidomastoid. The altered muscle activation patterns may contribute to the painful shoulder in elite swimmers and need to be considered within the rehabilitation interventions.

Comprehensive corrective exercise program improves alignment, muscle activation and movement pattern of men with upper crossed syndrome: randomized controlled trial.

Upper crossed syndrome (UCS) refers to the altered muscle activations and movement patterns in scapulae along with some abnormal alignment in the upper quarter, which may contribute to the dysfunction of the cervicothoracic and glenohumeral joints. The present study aimed to investigate the effectiveness of a comprehensive corrective exercise program (CCEP) and subsequent detraining on alignment, muscle activation, and movement pattern in men with the UCS. This randomized controlled trial included 24 men. The intervention group conducted CCEP (8 weeks), followed by four weeks of detraining and the control group maintained normal daily activities. Electromyography of selected muscles, scapular dyskinesis test, head, shoulder, and thoracic spine angle were measured at baseline, post-test, and follow-up. There were significant differences for Group x time interaction and also for within-group from pre-test to post-test and follow-up in all outcomes. Also, significant differences were observed in three outcomes at post-test and follow-up between the CCEP and control group in favor of the CCEP. In Conclusion, the present study demonstrates that the CCEP for individuals with UCS is feasible and effective, improving muscle activation imbalance, movement patterns, and alignment. Importantly, these improvements were maintained after four weeks of detraining, suggesting lasting neuromuscular re-training adaptations.

Comparison of some intrinsic risk factors of shoulder injury in three phases of menstrual cycle in collegiate female athletes.

OBJECTIVES: present study aims to investigate the changes in the shoulder joint stability factors during the menstrual cycle. DESIGN: cross-sectional study; SETTING: laboratory. PARTICIPANTS: 15 healthy collegiate female athletes with normal menstrual cycles. MAIN OUTCOME MEASURES: shoulder strength, proprioception, laxity and functional stability were the primary outcomes. Participants were assessed in three phases (mense, ovulation, midluteal (day 21) by 4 different categories of tests, each designed for a different factor. Shapiro-Wilk Test was used to determine normality of data, ANOVA and Friedman Test were used to compare results. Significance level and alpha were considered 95 percent and ≥0.05, respectively. Data shown a relation between proprioception, strength and menstrual cycle. RESULTS: shoulder strength was significantly increased in ovulation phase compared to other phases (p < 0.5) (effect size >0.14). Proprioception was significantly decreased in luteal phase than in mense and ovulation phases (p < 0.5) (effect size >0.14). Finally, ligament laxity and functional stability showed no change in all phases (p < 0.5). CONCLUSION: Menstrual cycle and sexual hormones affect muscle strength and proprioception of shoulder joint, but have no effect on ligament laxity and functional stability.