Strength and activity of the protractor and retractor muscles of the asymptomatic dyskinetic scapula.

The role of scapular dyskinesis as a risk factor of shoulder injury has been largely discussed. However, most studies have focused on symptomatic patients and less is known on the asymptomatic dyskinetic scapula. Removing the confounding effects of the pathologies could contribute to better characterize the scapula dyskinesis. As muscle properties (strength, fatigue, nerve injury …) have been identified as causative factors of scapular dyskinesis, this study focuses specifically on characterizing the protractor and retractor muscles of the dyskinetic scapula. Thirteen asymptomatic dyskinetic volunteers were compared to eleven asymptomatic non-dyskinetic control volunteers. Muscle characteristics were evaluated in terms of maximal strength, fatigue resistance and electromyographic activity during a functional closed-chained task. The results did not identify kinematic or muscle activity significant differences between the dyskinetic and the control group even in fatigue conditions. However, the results demonstrated that protractors vs. retractors fatigue resistance ratios were imbalanced (<0.8) in the dyskinetic group and significantly lower than in the non-dyskinetic one. Our study suggests that that strength imbalances are not necessarily related to the presence of pain at the shoulder joint. These results demonstrated the importance to complete the clinical assessments of the scapula with strength evaluations even for asymptomatic sport practitioners.

Upper limb functional testing in athletes: A Delphi study.

Background: Functional testing has recently become more and more popular to assess athletes, both for injury prevention, as well as in an objective of performance. However, the relationship between the results of these tests and performances (or injuries) or their interpretation remains unclear. Objective: The aim of this study is to explore the usefulness, the characteristics, and the interpretation of the most frequently used upper-limb functional test. Methods: Twenty-two experts with an excellent knowledge of upper limb functional tests and an expertise in sports medicine and/or sports training of at least 5 years were recruited. They answered to qualitative and quantitative questions about functional testing trough structured questionnaires (online). Results: Four rounds were needed to reach a consensus about the usefulness as well as the characteristics of each test. Different sports-specific batteries of tests were also suggested by the experts and reached consensus. However, concerning the interpretation of the test, a consensus was only found for half of the tests considered. Conclusion: The current study summarizes the characteristics and the usefulness of the most popular upper-limb functional tests. However, the interpretation of some tests will have to be further explored since no consensus was found for them.

Outcomes of Patients with Lower Limb Loss after Using a Training Prosthesis: A Retrospective Case Series Study.

The aim of this retrospective case series study was to investigate outcomes in patients with lower limb loss based on whether or not they used a training prosthesis (TP) during rehabilitation. The medical records of 171 consecutive patients admitted to rehabilitation hospitalization between January 2014 and December 2018 following a major amputation of the lower limb were reviewed. Patients were categorized into two groups: patients who underwent rehabilitation with a TP and patients who did not use a TP. Outcomes (i.e., discharge destination, length of stay, number of sockets required, and number of the size adaptation of each socket, as well as functional level) were compared between groups. Of the 171 patients, 126 underwent rehabilitation with a TP, and 45 patients underwent rehabilitation without any TP. In conclusion, we found that patients who used a TP had a significantly shorter hospital length of stay when compared to those who did not. This length of stay for patients with TP was not influenced by age but was lowered by a higher body mass index (BMI), tibial instead of femoral amputation, and the male gender. No association was found between the use of TP and discharge destination, functional level, number of socket modifications, and number of sockets required.

Finger counting to relieve working memory in children with developmental coordination disorder: Insights from behavioral and three-dimensional motion analyses.

A limited number of studies have attempted to understand how motor deficits affect numerical abilities in children with developmental coordination disorder (DCD). The purpose of this study was to explore the functionality of finger-counting (FC) in children with DCD. The participants, 15 children with DCD and 15 typically developing (TD) children matched on school level and fluid reasoning abilities, were asked to use FC to solve an ordinal task with high working memory (WM) load. Behavioral measures supplemented with biomechanical measures, from three-dimensional motion analysis synchronized to a voice recording were used to assess children's performance and FC functionality (total duration, inter-finger [IF] transition, IF variance, finger/voice synchronization, and automatization of FC movements). Children with DCD were less accurate than TD children in using FC to solve ordinal problems with high WM load. This group difference could not be accounted for by poor FC skills given that FC movement turned out to be as functional in children with DCD as in their TD peers. When added to the model as a covariate, WM captured a greater proportion of intergroup variability than manual dexterity, further suggesting that their difficulties would be better accounted for by limited WM resources than by fine motor skills.

Ankle strength assessed by one repetition maximum: A new approach to detect weaknesses in chronic ankle lateral instability.

BACKGROUND: Ankle muscle strength should be assessed after a lateral ankle sprain (LAS) because a strength deficit can lead to chronic ankle instability (CAI). No field method is available to obtain quantitative ankle dynamic strength values. This study aimed to assess the reliability of the one-repetition maximal (1-RM) method and to compare ankle muscle strength between healthy volunteers and those with CAI using 1-RM strength assessment approach. METHODS: We recruited 31 healthy volunteers and 32 with CAI. Dorsiflexor, evertor, and invertor 1-RM were performed twice at a one-week interval. The intraclass correlation coefficient (ICC) and minimal detectable change (MDC) were calculated. Strength values were compared between healthy volunteers and CAI. RESULTS: The 1-RM method is reliable for assessing ankle dorsiflexor, evertor, and invertor strength, with an ICC ranging from 0.76 to 0.88, and MDC ranging from 19 to 31%. Volunteers with CAI obtained evertor (3.0 vs. 3.5 N/kg), invertor (2.9 vs. 3.7 N/kg), and dorsiflexor (5.9 vs. 6.5 N/kg) strength values that were lower than healthy volunteers (p < 0.05). CONCLUSION: The 1-RM test can be used in practice to assess evertor, invertor, and dorsiflexor strength during the rehabilitation of LAS. This field method could help practitioners to detect a strength deficit and individualize a strengthening programme if necessary.

Prevention of shoulder injuries in volleyball players: The usefulness and efficiency of a warm-up routine.

OBJECTIVES: The objective of this study was to assess the efficiency of a warm-up routine focused on shoulder injury prevention in volleyball players. DESIGN: Prospective study. SETTING: University. PARTICIPANTS: Eight recreational volleyball teams (44 males, 49 females) were included in the study and assigned to two different groups (prevention or control) in a blinded way. In the prevention group, the players had to perform specific exercises at the beginning of each training session twice a week. MAIN OUTCOME MEASURES: Injuries were recorded monthly in both groups with an online questionnaire. RESULTS: A significant decrease in the total number of injuries as well as in the severity of the injuries was observed in the prevention group in comparison to the control group (p = 0.0001-0.013). For the shoulder, a decrease in injury incidence was also observed in the prevention group. This decrease reached significance in male players (p = 0.045). CONCLUSIONS: The program appears to be efficient to reduce the risk of shoulder injuries in recreational volleyball players. Adjustments in the duration and in the contents of the program will have to be made to further improve compliance and better meet the requirements of both players and trainers.

Contribution of finger gnosia and fine motor skills to early numerical and arithmetic abilities: New insights from 3D motion analyses.

Finger gnosia and fine motor skills (FMS) are assumed to play a key role in the development of arithmetic abilities, but their contribution to early numerical skills (i.e., enumeration skills and cardinality) has received little attention so far. The purpose of this study was to investigate the predictive value of finger gnosia and FMS to enumeration, cardinal, and arithmetical abilities and how these different dimensions contribute to arithmetic development. Overall, 3- to 5-year-old preschoolers were asked to perform tasks assessing enumeration, cardinality, and early arithmetic, as well as finger gnosia and FMS. FMS, involving either static or dynamic fine finger movement, were examined using 3D motion analyses. Using hierarchical regression, FMS were found to be the best predictor of both cardinality and early arithmetic skills, while finger gnosia did not predict the additional variance of arithmetic performance when FMS and age were considered in the regression model. Moreover, neither finger gnosia nor FMS were significant predictors of enumeration. Mediation analyses indicated that knowledge of the cardinal principle fully mediates the relationship between FMS and arithmetic skills, suggesting that FMS contribute to cardinal principle knowledge development, which would be a gateway to more complex arithmetical processing. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Foot and Ankle Muscle Isometric Strength in Nonrearfoot Compared With Rearfoot Endurance Runners.

Background: Transitioning to a forefoot strike pattern can be used to manage running-related knee injuries. However, adopting a nonrearfoot strike induces a higher load on foot and ankle structures than rearfoot strike. Sufficient foot muscle strength is also necessary to prevent excessive longitudinal arch (LA) deformation when running with nonrearfoot strike. The aim of this study was to investigate the potential differences in foot-ankle muscle strength between RF and NRF runners. Methods: A cross-sectional study including 40 RF and 40 NRF runners was conducted. The foot posture and the maximal voluntary isometric strength (MVIS) of 6 foot-ankle muscles were measured. The footstrike pattern was determined using a 2-D camera during a self-paced run on a treadmill. Results: NRF had higher MVIS for ankle plantar flexor (+12.5%, P = .015), ankle dorsiflexor (+17.7%, P = .01), hallux flexor (+11%, P = .04), and lesser toe flexor (+20.8%, P = .0031). We found a small positive correlation between MVIS of ankle plantar flexor with MVIS of hallux flexor (r = 0.26; P = .01) and lesser toe flexor (r = 0.28; P = .01). Conclusion: In this cross-sectional study, we found that NRF runners on average have a higher MVIS of hallux and lesser toe flexor compared with RF runners. NRF runners also have a higher MVIS of ankle plantar flexor and dorsiflexor than RF runners. We found only a small correlation between ankle plantar flexor and foot muscle strength. Level of Evidence: Level III, case-control study.

Nitroglycerin trapping in melamine matrices.

Melamine (Mel) was used as host matrix for liquid nitroglycerin (NG), to prepare Mel/NG solid powdered compounds containing up to 45 wt% of this explosive. The two preparation processes used for this purpose consisted in evaporating a solution of both components, either in ambient conditions or under reduced pressure by the Spray Flash-Evaporation (SFE) process. In Mel/NG materials, amorphous nitroglycerin is distributed in the crystallized melamine matrix as inclusions, which were found to be smaller in size in the material prepared by the SFE process. Mel/NG materials are not stable over time: they gradually lose the nitroglycerin they contain by evaporation.

Differences in strength and fatigue resistance of scapular protractors and retractors between symptomatic and asymptomatic dyskinesis.

CONTEXT: Scapular dyskinesis is a shoulder dysfunction that can be asymptomatic or associated with pain or weakness. Reduced strength and fatigue resistance of the scapular protractor and retractors muscles that stabilize the scapula might contribute to dyskinesis. OBJECTIVE: To determine the strength and fatigue resistance profiles of subjects with symptomatic and asymptomatic scapular dyskinesis, and to compare them to healthy controls using isokinetic assessment. DESIGN: Cross-sectional study. SETTING: University Hospital. PARTICIPANTS: Twenty healthy controls and 21 overhead athletes with symptomatic (n=10) and asymptomatic (n=11) scapular dyskinesis. MAIN OUTCOME MEASURES: Strength (peak torque, maximum work), fatigue resistance (total work) and protraction/retraction ratios measured during a closed-chain isokinetic protocol (40 repetitions in concentric mode at 24.4 cm/s). RESULTS: The scapular protractors' strength and fatigue resistance were significantly higher (p<0.01) in healthy controls (peak torque: 5.0±0.9 N/Kg; maximum work: 2.4±0.5 J/Kg; total work: 72.4±0.6 J/Kg) than in asymptomatic (peak torque: 3.4±0.7 N/Kg; maximum work: 1.7±0.4 J/Kg; total work: 50.0±13.7 J/Kg) and symptomatic (peak torque: 3.8±0.6 N/Kg; maximum work: 1.8±0.3 J/Kg; total work: 58.1±12.9 J/Kg) dyskinetic participants. The dyskinetic symptomatic group presented the highest retractors' strength and fatigue resistance (p<0.01) values (peak torque: 5.2±0.6 N/Kg; maximum work: 2.9±0.8 J/Kg; total work: 87.7±22.7 J/Kg) followed by the healthy controls (peak torque: 4.7±1.0 N/Kg; maximum work: 2.1±0.5 J/Kg; total work: 65.3±17.9 J/Kg) and the asymptomatic dyskinetic participants (peak torque: 3.9±1.0 N/Kg; maximum work: 1.9±0.6 J/Kg; total work: 58.6±18.5 J/Kg). The protraction / retraction ratios showed a gradual decrease (p<0.001) from healthy controls (1.1) to asymptomatic (0.9) and symptomatic (0.7) dyskinetic subjects. CONCLUSIONS: Scapular dyskinesis is characterized by weaker scapular protractors and reduced agonist/antagonist ratios, especially when symptomatic. Targeting the scapular protractors for a better balance of scapular musculature in rehabilitation and strengthening programs may improve shoulder symptoms and function, but more interventional studies are required.

Preseason shoulder screening in volleyball players: is there any change during season?

Background: Volleyball players sollicit their shoulder with high velocity and high ranges of motion. Musculoskeletal adaptations have been described after some years of practice but have not been explored after some months of practice. The objective of this study was to analyze the short-term evolution of shoulder clinical measures and functional performance in youth competitive volleyball players. Methods: Sixty-one volleyball players were assessed twice, at preseason and at midseason. Shoulder internal and external rotation range of motion as well as forward shoulder posture and scapular upward rotation were measured in all players. Two functional tests were also performed: the upper quarter Y-balance test and the Single-arm medicine ball throw. The results obtained at midseason were compared to those measured at preseason. Results: Compared to preseason, an increase in absolute value of shoulder external rotation, total rotation range of motion and forward shoulder posture were observed at midseason (P < .001). An increase in side-to-side difference for shoulder internal rotation range of motion was also observed during the season. As for scapular kinematics, scapular upward rotation was significantly decreased at 45° and increased at 120° of abduction at midseason. Concerning functional tests, an increase in throwing distance in the single-arm medicine ball throw was observed at midseason while no change was noted for the upper quarter Y-balance test. Conclusion: Significant changes in clinical measures and functional performance were observed after some months of practice. Since some variables have been suggested to be correlated to a higher risk of shoulder injuries, the current study emphasizes the importance of regular screening in order to highlight injury risk profiles throughout the season.

Survey of physicians' and physiotherapists' ankle muscle strength assessment practices for safe return to sports after lateral ankle sprain: A short report.

BACKGROUND AND PURPOSE: Ankle muscle strength is an important criterion to consider and assess for return to play (RTP) after lateral ankle sprain (LAS). This study therefore focuses on the reported ankle muscle strength consideration for RTP by physicians and physiotherapists, both clinicians involved in RTP decisions, and how they assess it in daily practice. The primary aim is to compare reported clinical practice on ankle muscle strength evaluation between physicians and physiotherapists. Our secondary aims are: to assess the prevalence of use of qualitative versus quantitative assessment and; to determine if there are any differences in how clinicians with or without a Sports Medicine or Physiotherapy Education approach this assessment. METHODS: A survey on RTP criteria after LAS was completed by 109 physicians in a previous study. A number of 103 physiotherapists completed the same survey. A comparison between clinicians' answers was realized and additional questions on ankle muscle strength were analysed. RESULTS: Physiotherapists consider ankle strength for RTP more than physicians (p < 0.001). A large majority of physicians (93%) and physiotherapists (92%) reported assessing ankle strength manually and less than 10% use a dynamometer. Physicians and physiotherapists with Sports Medicine or Physiotherapy Education selected more quantitative assessment than those without (p < 0.001). DISCUSSION: Despite being recognized as an important criterion, ankle muscle strength is not always part of the RTP criteria after LAS in daily practice. The dynamometers are scarcely used by physicians and physiotherapists, whereas it could accurately quantify ankle strength deficits. Sports Medicine or Physiotherapy Education increases the use of quantitative ankle strength assessments by clinicians.

Preseason assessment of anaerobic performance in elite soccer players: comparison of isokinetic and functional tests.

Isokinetic and functional jump tests are frequently performed for assessing the physical qualities of soccer players during preseason. The purpose of this investigation was to explore, in an elite soccer players population, the relationships between isokinetic strength and functional jump performances. Thirty-eight professional soccer players were evaluated as follows: isokinetic knee assessment in concentric (CON) mode (60, 240°/s) for quadriceps and hamstrings, and in eccentric (ECC) mode for the hamstrings only (30°/s); one-leg hop tests for distance (single hop (SH), triple hop (TH) and triple crossover hop (TCH)); one-leg vertical jump tests (countermovement jump, drop jump). Players with a low bodyweight normalised (BWN) quadriceps (Q) strength (<2.71 Nm/kg) performed, for a majority of the measured variables, significantly reduced jump performances compared to the players with high BWN Q strength (>3.14 Nm/kg; p < 0.05). Greater bilateral differences between uninjured and past injured lower limbs were found with isokinetics (Q CON 60°/s (mean bilateral difference (MBD): 10.3%; p < 0.01), Q CON 240°/s (MBD: 9.9%; p < 0.05), H ECC 30°/s (MBD: 16.1%; p < 0.001) than with functional tests (MBD: 2 to 9%; p > 0.05. In conclusion, due to their complementary role and implications for performance, functional and isokinetic tests should be associated in a preseason soccer players assessment.

The Modified-Athletic Shoulder Test: Reliability and validity of a new on-field assessment tool.

OBJECTIVES: To assess the reliability and the validity of a modified version of the Athletic Shoulder Test (M-AST), using a handheld dynamometer instead of a force plate. DESIGN: Test-retest reliability and concordance between tools. SETTING: University Motion Lab. PARTICIPANTS: Twenty healthy volunteers who practiced an upper limb sport for at least 5 h per week were recruited for the study. MAIN OUTCOME MEASURES: The concordance between the Athletic Shoulder Test (AST) and the Modified-Athletic Shoulder Test (M-AST) was assessed with intra-class correlation coefficients (ICC), paired T-Test and Bland-Altman plots. The inter-session reliability was assessed with intra-class correlation coefficients (ICC), SEM, MDC and paired T-Test. RESULTS: A strong concordance was found between AST and M-AST values (ICC = 0.86-0.97; p > 0.05) in all the positions considered and for both sessions. Bland-Altman plots confirmed these results. However, the inter-session reliability was more variable for both AST and M-AST (ICC = 0.643-0.923; p < 0.05). CONCLUSIONS: The M-AST seems to be a reliable, cheaper and easier to implement alternative to the AST to measure recovery status following matches or training sessions in upper limb athletes. As for the AST, familiarization trials will have to be performed before the assessment to have accurate measurements. CLINICAL TRIALS REGISTRATION NUMBER: NCT05112380.

The influence of growth and development on shoulder rotators strength in young male and female elite tennis players.

BACKGROUND: Tennis practice requires a lot of technical, physical and mental qualities that have to be trained from the youngest age. The important number of hours spent on the court can lead, medium-to-long term to strength or flexibility adaptations, even in the youngest players. The current study aimed to explore the developmental consequences of repetitively playing tennis on shoulder range of motion and shoulder rotators' strength in elite male and female tennis players. METHODS: Eigthy four painfree elite tennis players were assessed during preseason between 2009 and 2019. Clinical assessment included internal and external rotation range of motion and forward shoulder posture while maximal internal and external rotators strength were assessed with an isokinetic dynamometer in concentric and in eccentric modes (at 60°/s and 240°/s). RESULTS: In male players, growth and maturation induced an increase in forward shoulder posture. Absolute peak torque and bodyweight peak torque of internal and external rotators in concentric and eccentric mode were also significantly increased during with age while ER/IR concentric ratios were significantly decreased. In the female players, only absolute peak torque of internal and external rotators in concentric mode and eccentric strength of external rotators were significantly influenced by the development. CONCLUSIONS: Specific adaptations were found in male and female players with age and practice. The important variability in the results within the different age categories and the gender strengthens the importance of regular screening (and isokinetic evaluations) in young tennis players in order to highlight potential atypical profiles, which could have a negative influence on performance or increase the risk of injuries during the development of the player.

Current practice for safe return-to-play after lateral ankle sprain: A survey among French-speaking physicians.

BACKGROUND: Recommendations are available for assessment criteria for safe return-to-play (RTP) after a lateral ankle sprain. However, their current use among physicians is unknown. METHODS: French-speaking physicians in Belgium, France and Switzerland were asked to complete an online survey and report their clinical assessment of selected RTP criteria. RESULTS: The respondent sample (n=109) included physicians with and without Sports Medicine education, varied level of experience and proportion of athletes in their practice population. Pain was the most selected criterion for safe RTP (90% of physicians), followed by ability to engage in functional tasks (82%), functional instability (73%), range of motion (61%), proprioception (47%), mechanical instability (39%), strength (38%) and swelling (31%). A low proportion of physicians use quantitative measures to assess these criteria (between 4% and 53%). CONCLUSIONS: A large proportion of physicians consider the recommended criteria for RTP decisions. However, physicians do not frequently use quantitative measures.

Evolution of the trophy position along the tennis serve player's development.

The trophy position is a coaching cue for the tennis serve that usually corresponds to the racquet high point (RHP) during the preparatory action for the stroke. Mastering this position and its time of occurrence seems essential in overarm movements like in the tennis serve. Clinicians and coaches have a real interest in understanding the trophy position and its evolution during the development of the elite players at different ages. A 3D motion system was used to measure the kinematics of the serve. A group of high-level tennis players were selected for three different age groups: 8 adults (ITN 1), 8 teenagers (ITN 3) and 8 children (ITN 5-6). Results show a modified pattern sequence of the tennis serve between children and adult players. RHP appears earlier relative to impact for children (-0.54 ± 0.10 s) than for adults (-0.36 ± 0.11 s) and teenagers (-0.33 ± 0.05 s) (p = 0.007). At RHP, children present lower trunk transverse plane rotation (p < 0.003) and higher shoulder external rotation (p < 0.003). These positions for the child players may represent an increased risk of shoulder and trunk injury than for older players and contribute to a lower racquet resultant velocity at impact.

Tight shoulders: A clinical, kinematic and strength comparison of symptomatic and asymptomatic male overhead athletes before and after stretching.

A tightness of the posterior structures of the throwing shoulder has been hypothesised to be associated with injuries and pain because of alterations of the scapular kinematics and muscular imbalances. The aims of this study were to identify the clinical and biomechanical profile of symptomatic and asymptomatic overhead athletes with a tight shoulder and to evaluate the efficiency of a self-applied stretching program. Twenty male overhead athletes were recruited. Half of them reported a painful shoulder at the beginning of the study. For four weeks, the volunteers performed daily stretching exercises. Before and after the stretching program, gleno-humeral mobility, scapular kinematics, rotator muscles strength and pain were evaluated. Before stretching, the main difference between the groups was more impingement syndrome and rotator cuff tendon lesion positive tests in the symptomatic group (p < 0.027, effect size = 0.51). After the program, pain reported by the symptomatic volunteers was reduced by approximately 40% and the gleno-humeral internal rotation bilateral difference was significantly reduced by 77.6% (p < 0.009, effect size = 0.84). In the symptomatic group, the scapula at rest was significantly more posteriorly tilted (p = 0.027, effect size = 0.69) after the stretching; a position that has been shown to limit the risk of impingement. The absence of significant differences of the profiles of the symptomatic and asymptomatic overhead athletes before stretching may indicate that the initiation of early prevention programs, including self-applied stretching, should not rely solely on biomechanical and clinical parameters and might be recommended to all players with a tight shoulder.

Normalizing gastrocnemius muscle EMG signal: An optimal set of maximum voluntary isometric contraction tests for young adults considering reproducibility.

BACKGROUND: Even though most studies normalize the surface EMG signal of the gastrocnemius muscle using a single position of maximum voluntary isometric contraction (MVIC), several studies tend to indicate that several positions are in fact needed to obtain a maximal voluntary activation (MVA) for most of the subjects. However, no combination of positions has already been described. RESEARCH QUESTION: A combination of MVIC positions to normalize the EMG signal of the gastrocnemius muscle is investigated. the influence of using several positions on the reproducibility of the normalization process is evaluated. METHODS: Twenty healthy volunteers (45 % female - 55 % male, 25.4 years (SD 4.3), 72.6 kg (SD 13.9), 1.78 m (SD 0.12)) were recruited. Six positions for MVIC were compared and the effect of several normalization combinations on a functional task (gait) was evaluated. RESULTS: Several positions are needed to obtain at least 90 % of the MVA for 90 % of the volunteers even though the use of a single well-chosen position (unipodal standing position with knee fully extended and ankle fully plantar-flexed) will lead to no statistically significant differences of the gait evaluation during stance phase. For each position, five repetitions of the MVIC are recommended to obtain a valid MVA. SIGNIFICANCE: This study confirms that using several MVIC positions is recommended when possible to normalize the gastrocnemius muscle EMG signal. However, in the situation of a patient where limited MVIC attempts are possible, using a single well-chosen position should not significantly influence the amplitude and the reproducibility of the measures.

Risk Factors of Overuse Shoulder Injuries in Overhead Athletes: A Systematic Review.

CONTEXT: Shoulder injuries are highly prevalent in sports involving the upper extremity. Some risk factors have been identified in the literature, but consensus is still lacking. OBJECTIVES: To identify risk factors of overuse shoulder injury in overhead athletes, as described in the literature. DATA SOURCES: A systematic review of the literature from the years 1970 to 2018 was performed using 2 electronic databases: PubMed and Scopus. STUDY SELECTION: Prospective studies, written in English, that described at least 1 risk factor associated with overuse shoulder injuries in overhead sports (volleyball, handball, basketball, swimming, water polo, badminton, baseball, and tennis) were considered for analysis. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: Data were extracted from 25 studies. Study methodology quality was evaluated using the Modified Coleman Methodology Score. RESULTS: Intrinsic factors, previous injury, range of motion (lack or excess), and rotator cuff weakness (isometric and isokinetic) highly increase the risk of future injuries. Additionally, years of athletic practice, body mass index, sex, age, and level of play seem to have modest influence. As for the effect of scapular dysfunction on shoulder injuries, it is still controversial, though these are typically linked. Extrinsic factors, field position, condition of practice (match/training), time of season, and training load also have influence on the occurrence of shoulder injuries. CONCLUSION: Range of motion, rotator cuff muscle weakness, and training load are important modifiable factors associated with shoulder injuries. Scapular dysfunction may also have influence. The preventive approach for shoulder injury should focus on these factors.