Effect of Acupuncture on Muscle Endurance in the Female Shoulder Joint: A Pilot Study

Shoulder joint dysfunction is the leading cause of decreased athletic ability in athletes. Shoulder joint sports injuries affect the athletic performance of athletes. Improvements in the muscle endurance of the shoulder joint can reduce the incidence of shoulder joint dysfunction. Acupuncture has been an important part of Asian culture for a long time. In acupuncture, nerves are stimulated, inducing postactivation potentiation (PAP) in the body's motor units and enhancing muscle strength. In this research, 20 female participants with full flexion/extension and adduction/abduction ranges of motion in the shoulder joint during isokinetic exercises underwent stimulation of the following acupuncture points in the shoulder joint: Binao (LI14), Jianyu (LI15), Jianliao (SJ14), Naohui (SJ13), Yuzhong (KI26), Zhongfu (LU1), Yunmen (LU2), Xiabai (LU4), Chize (LU5), Tianfu (LU3), and Xiaoluo (SJ12). In the study, there were significant increases after acupuncture in the average maximum torque in flexion, extension, and adduction; the average work in flexion/extension and adduction/abduction; the average power in flexion/extension and adduction/abduction; the total work in flexion/extension and adduction/abduction; the total net sagittal-plane work (flexion + extension); and the total net frontal-plane work (adduction + abduction) (P < 0.05). The average maximum abduction torque did not increase significantly, potentially due to antagonistic forces of muscles. Therefore, acupuncture at acupoints around the shoulder joint can increase muscle excitability, thereby delaying muscle fatigue and increasing muscle endurance.