Electromyography activity of the deltoid muscle of the weight-bearing side during shoulder flexion in various weight-bearing positions

[Purpose] This study investigated the deltoid muscle activation during shoulder flexion exercise in various weight-bearing positions. [Subjects] A total of 15 males participated. [Methods] The participants completed three repetitions of shoulder flexion exercises in three positions (prone-on-elbow, quadruped, and standing) with electromyography activity being collected from the exercised. The muscle activations in each position by each exercise were compared using a one-way analysis of variance. [Results] The electromyography activities of the middle and posterior deltoids differed significantly among positions. The prone-on-elbow and quadruped position showed a significantly higher activity than the standing position. There were no significant differences between the prone-on-elbow and quadruped positions. [Conclusion] The deltoid muscles were further strengthened in the low posture positions (prone-on-elbows and quadruped) than in standing.