The Impact of Eight Weeks Closed and Open Kinetic Chain Exercise on Ratio of the External to Internal Shoulder Rotator Muscles’ Strength in Top Swimmers

Abstract

Objectives: Based on previous studies, the strength ratio of internal to external rotator muscles of the shoulder in elite swimmers is a predisposing factor of impingement syndrome. So this study was done to compare the effect of open and closed kinetic chain exercises on this ratio. Methods: Regarding the inclusion criteria, 45 swimmers were selected and distributed randomly to 3 groups of the open chain (15), closed chain (15), and control (15). Exercise prescribed for both open and closed chain groups three times per week, but the control group was deprived. Before starting the exercise and after eight weeks, the strength ratio of the internal to the external rotator shoulder muscles in both eccentric and concentric contraction was measured at various speeds of 60, 120, and 180 degrees/s. Subsequently, one-way ANOVA and Tukey post hoc tests were performed to compare the groups and show the intra-group difference (P < 0.05). Results: Both types of exercises reduced the strength ratio of internal to external shoulder rotator muscles in both contractions. There was no significant difference between closed and open chain exercises, but the open chain reduced the ratio of internal to external rotator muscles’ strength less than the closed chain in both types of contractions. Conclusions: To reduce the ratio of internal to external rotator muscles’ strength in swimmers and improve the muscle imbalance, open kinetic chain exercises are more effective than closed kinetic chain exercises and can be recommended for prevention and rehabilitation of swimmer’s shoulder.