Activation of Supraspinatus and Infraspinatus Partitions and Periscapular Musculature During Rehabilitative Elastic Resistance Exercises.

OBJECTIVE

The purpose of this study was to quantify the activation of partitions within supraspinatus and infraspinatus and some periscapular muscles during four resistance exercises with elastic bands.

DESIGN

Twenty-seven right-handed healthy volunteers (age, 22.5 ± 2.7 yrs) were recruited. Intramuscular electromyography from supraspinatus (anterior and posterior) and infraspinatus (superior and middle) and surface electromyography data from the upper, middle, and lower trapezius and serratus anterior were recorded during four elastic resistance exercises (Y, T, W, L). Kinematics were recorded synchronously. Electromyography values were presented as percentage of maximal voluntary isometric contraction and compared across exercises using analysis of variance. Muscle activation ratios were also calculated.

RESULTS

The mean activations of all rotator cuff partitions were more than 40% maximal voluntary isometric contraction, except middle infraspinatus during the T exercise (29.3% maximal voluntary isometric contraction). Serratus anterior activity was significantly higher during the Y exercise (P < 0.008). Lower trapezius was activated more than 80% maximal voluntary isometric contraction in all four exercises with higher contributions compared with the upper trapezius.

CONCLUSIONS

The investigated exercises induced moderate to high activation in supraspinatus and infraspinatus partitions and very high activation in lower trapezius. YTWL exercises are appropriate for strengthening of some rotator cuff and periscapular muscles and for late stages of shoulder rehabilitation.