Relative scapular-muscle ratios during maximal isokinetic shoulder-girdle strength performance in elite field hockey players

Context: The shoulder joint and girdle are highly loaded during field hockey play. To optimize performance and to better substantiate preventive programs, it is important to gain insight into shoulder-girdle muscle function and balance in this athlete population. Objective: To evaluate relative scapular muscle-activity ratios through surface electromyography during maximal isokinetic strength testing in elite male field hockey players compared with nonathletes. Design: Cross-sectional study. Setting: Institutional laboratory. Patients or Other Participants: Twenty-five elite field hockey players from the Belgian National Team and 25 age-and sex-matched nonathletes. Intervention(s): We measured bilateral activity in 4 scapular muscles (upper trapezius [UT], middle trapezius [MT], lower trapezius [LT], and serratus anterior [SA]) during an external-internal rotation and protraction-retraction isokinetic shoulder protocol. Main Outcome Measure(s): Relative scapular muscleactivity ratios, or balance ratios, of the UT : MT, UT : LT, UT: SA, SA : MT, and SA : LT. Results: We noted lower ratios bilaterally in the athlete group compared with the control group for the UT: MT, UT: LT, and SA: MT ratios during protraction, retraction, and external rotation, respectively, and unilaterally (dominant side only) for the UT: LT ratio during protraction. No consistent trend was present for established side differences in the studied balance ratios. Conclusions: Compared with nonathletes, elite field hockey players had altered intramuscular (within the trapezius) and intermuscular (between the trapezius and SA) balance ratios during maximal shoulder-girdle contractions, with relatively more MT and LT activity. This may reflect a sport-specific adaptation to optimize coordinated activity of the scapulothoracic muscles, meeting the specific demands of field hockey movements and simultaneously better protecting the shoulder against injury. Our results can assist in optimizing high-performance training and in supporting injury-prevention programs, which are key to both successful and long-lasting athletic careers

Upper-extremity functional performance tests : reference values for overhead athletes

This study aimed to provide an age, gender and sport-based normative database for three functional shoulder tests: Y Balance Test - Upper Quarter (YBT-UQ), Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST), and Seated Medicine Ball Throw (SMBT). A second aim was to discuss gender, age and sports differences. Finally, correlation between tests was evaluated. Overhead athletes (106 male, 100 female) between 18 and 50 years old and from three different sports (volleyball, tennis, handball) performed all functional tests. A linear mixed or regression model was applied to determine significant differences in test scores between gender, age and sports. Pearson correlation coefficients were analyzed to determine the relationship between tests. Normative values were established and divided by gender, sports and age. Results showed significant gender and age differences for all tests. For YBT-UQ, also significant side and sports differences were recorded. CKCUEST is moderately correlated with SMBT and YBT-UQ. Weak correlation was found between SMBT and YBT-UQ. In conclusion, this study provides normative data for YBT-UQ, CKCUEST and SMBT, which is clinically relevant for functionally screening overhead athletes and benchmark their performance to others from the same gender, age and sports. A combination of included tests is recommended

Incorporation of the kinetic chain into shoulder-elevation exercises : does it affect scapular muscle activity?

Context: Scapular rehabilitation exercises should focus on selective activation of weaker muscles and minimal activation of hyperactive muscles. For rehabilitation of overhead athletes, single-plane open chain exercises below 90 degrees of shoulder elevation are often recommended. Moreover, incorporating the kinetic chain in shoulder rehabilitation exercises is advised and has been suggested to influence scapular muscle activity levels. Objective: To study the influence of kinetic chain incorporation during 5 variations of a shoulder-elevation exercise on scapular muscle activity. Design: Cross-sectional study. Setting: University laboratory. Patients or Other Participants: Thirty-one asymptomatic participants (15 men, 16 women). Main Outcome Measure(s): The electromyographic activity of the upper (UT), middle (MT), and lower (LT) trapezius, and serratus anterior was determined during 5 variations of bilateral elevation with external rotation: (1) open-hand position (reference exercise), (2) closed-hand position, (3) dynamic bipedal squat, (4) static unipedal squat, and (5) dynamic unipedal squat on the contralateral leg. All data were normalized as a percentage of maximal voluntary isometric contraction (MVIC). Results: A closed-hand position (exercise 2) instead of an open-hand position (exercise 1) resulted in lower MT (mean difference = 3.44% MVIC) and LT (mean difference = 7.76% MVIC) activity. Incorporating the lower limb (exercises 3-5) increased UT activity when compared with exercise 1 (mean differences = 3.67, 2.68, 5.02% MVIC, respectively), which in general resulted in increased UT: MT ratios. Additionally, LT activity decreased when a dynamic unipedal squat was added (mean difference: 4.90% MVIC). For the serratus anterior, the greatest activity occurred during elevation in a static unipedal squat position (exercise 4, 22.90% MVIC). Conclusions: Incorporating the kinetic chain during shoulder-elevation exercises influenced scapular muscle activity and ratios. In particular, incorporating the lower limb resulted in more UT activity, whereas the open-hand position increased MT and LT activity