Relationship between muscle strength during closed kinetic chain exercise using upper extremities at different flexion angles of the shoulder joint and basic activities

Abstract

The purposes of this study were to compare muscle strengths during closed kinetic chain (CKC) exercise using upper limbs at different flexion angles of the shoulder joint, and to clarify the relationship between these muscle strengths and basic activities. Fourteen healthy women aged 19.1 ± 1.2 years (mean ± SD) participated in this study. The extensor muscle strengths during CKC exercise using upper extremity were measured under twelve conditions combining each shoulder flexion angle of 0, 30, 60 and 90 degrees with velocities of 60, 180 and 300 degree/sec. The three basic activities, wheelchair driving time on a 10 m path, the number of push-ups performed in 30 seconds, and the ratio of weight bearing relieved by loading on a T-cane to body weight, were measured under subjects' maximum effort. The muscle strengths (peak torque/body weight) during CKC exercise using the upper extremity did not show significant differences among shoulder flexion angles at all exercise velocities. Peak torque/body weight in all movement directions at 300 degree/sec tended to relate inversely to the wheelchair driving time, whereas there was no significant relationship between muscle strengths and the number of push-ups. In addition, peak torque/body weight in all exercise directions at 60 degree/sec tended to correlate with the ratio of weight bearing relieved by loading on a T-cane. In particular, there was a significant relationship between peak torque/bodyweight in shoulder flexion angle of 30 degrees at 60 degree/sec and the ratio of weight bearing relieved by loading on a T-cane. These results suggest that there is no exercise direction specificity, even though muscle strengths of CKC exercise using upper extremity at different flexion angles of the shoulder joint should reflect participation of various muscles and different contractile recruitment ratios. In addition, wheelchair driving time on a 10 m path may be influenced by velocity specificity but not by difference of motion direction, and the ratio of weight bearing relieved by loading on a T-cane may reflect specificities in both velocity and exercise direction of muscle strengths.