The effect of base of support stability on shoulder muscle activity during closed kinematic chain exercises.

Summary: METHOD: A total of thirty eligible subjects (17 female and 13 male, age = 22.26 ± 0.99 years, height = 170.96 ± 8.42 cm, weight = 61.63 ± 9.92 kg) were tested in six different randomly ordered positions. Surface Electromyography (EMG) was recorded from the upper trapezius (UT), lower trapezius (LT), serratus anterior (SA), long head of the biceps (LB), teres major (TM) and posterior deltoid (PD) muscles in the dominant shoulder in 6 different closed kinetic chain (CKC) positions. OBJECTIVE: To investigate changes in muscular activity of the shoulder muscles at different base of support stability levels. RESULTS: Muscle activity was greater in the most stable position for all muscles except UT (P < 0.01). CONCLUSION: Shoulder muscle activity did not increase in parallel with a reduction in base of support stability in the present study.