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.

Return to play decision after shoulder dislocation in upper limb athletes: Critical analysis between the habits of medical professionals and the literature.

BACKGROUND: The return to field is a critical moment for an athlete who has dislocated his shoulder as there is a significant risk of recurrence. The decision to return to field made by the doctor will therefore be crucial for the smooth continuation of the athlete's career. HYPOTHESIS: This objective is to compare the criteria most used by specialists in clearing an overhead athlete to return to competition after a first episode of antero-internal dislocation of the glenohumeral joint with or without surgery and those mentioned in the literature. PATIENTS AND METHODS: The target population consisted of French-speaking physicians in orthopedic surgery, physical medicine and rehabilitation or sports medicine. This study was conducted by the means of a questionnaire. The questionnaire was validated by three experts in sports medicine and published on an online survey website. RESULTS: Sixty-three medical specialists responded to the questionnaire. On average, they use more than nine criteria to decide if an athlete is fit to return to competition. Over the 12 criteria proposed, four are used by more than 90% of respondents: laxity/instability, pain, range of motion and patient's subjective feeling. The methods used to evaluate certain criteria such as pain, joint range or muscular strength are often subjective and very often not validated by the literature. CONCLUSION: Doctors use a set of criteria to allow an overhead athlete to return to competition. This study highlights that the techniques employed to evaluate these criteria are not always thoroughly validated by literature reviews. LEVEL OF EVIDENCE: III; observational study.

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.

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.

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.

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.

Activation Profile of Scapular Stabilizing Muscles in Asymptomatic People: Does Scapular Dyskinesis Have an Impact on It?

OBJECTIVE: The aim of the study was to assess the activation profile of scapular stabilizing muscles in dyskinetic asymptomatic people. DESIGN: This is a noninterventional observational study. Two groups of 20 people were included in the study. The first group involved asymptomatic athletes with scapular dyskinesis. The second one included athletes without scapular dysfunction. Muscle activation of upper trapezius, lower trapezius, and serratus anterior were recorded by a surface electromyography during shoulder flexion and shoulder abduction, in unloaded and loaded conditions. RESULTS: A significant increase of the activity of the upper trapezius (between 23% and 31%) and a significant decrease of the activity of the lower trapezius (between 32% and 65%) were observed in the dyskinetic group in comparison with the nondyskinetic group in asymptomatic athletes. A significant increase between 17% and 31% of the activity of the serratus anterior was also observed in dyskinetic people. Likewise, a significant increase approximately 24%-61% and 23%-70% was noted respectively in upper trapezius/lower trapezius and upper trapezius/serratus anterior ratio's in the dyskinetic group. CONCLUSIONS: An alteration of periscapular muscular activation exists in dyskinetic asymptomatic people. Future studies will be needed to know whether those alterations increase the risk of shoulder injuries.

Kinesiotaping for scapular dyskinesis: The influence on scapular kinematics and on the activity of scapular stabilizing muscles.

Scapular dyskinesis is observed in 61% of overhead athletes (Burn et al., 2016). For most of them, it remains asymptomatic. However, scapular dyskinesis is considered a risk factor for shoulder injury by some authors (Clarsen et al., 2014). The aim of this study is to explore the effectiveness of kinesiotaping in modifying scapular kinematics and peri-scapular muscle activity in dyskinetic athletes. The 3-dimensional position and orientation of the scapula as well as the activation of upper trapezius, lower trapezius and serratus anterior were recorded in twenty asymptomatic athletes during shoulder movements (flexion and abduction), in loaded and unloaded conditions and in three circumstances (standard, kinesiotaping 1, kinesiotaping 2). A significant decrease between 9 and 12% in upper trapezius activity was observed with kinesiotaping 1 and 2. Lower trapezius activity was slightly increased with kinesiotaping 1 while it was significantly decreased about 15-20% with kinesiotaping 2. No change was observed in serratus anterior activity, for either kinesiotaping 1 or 2. Considering scapular kinematics, both kinesiotaping 1 and 2 significantly increased posterior tilt and upward rotation. External rotation was decreased with kinesiotaping 2, in comparison to standard condition. Kinesiotaping, and especially taping 1, seems to be an effective method for changing periscapular muscle activity and scapular kinematics.