title: Effect of Selective Muscle Training Using Visual EMG Biofeedback on Infraspinatus and Posterior Deltoid.
abstract: We investigated the effects of visual electromyography (EMG) biofeedback during side-lying shoulder external rotation exercise on the EMG amplitude for the posterior deltoid, infraspinatus, and infraspinatus/posterior deltoid EMG activity ratio. Thirty-one asymptomatic subjects were included. Subjects performed side-lying shoulder external rotation exercise with and without visual EMG biofeedback. Surface EMG was used to collect data from the posterior deltoid and infraspinatus muscles. The visual EMG biofeedback applied the pre-established threshold to prevent excessive posterior deltoid muscle contraction. A paired t-test was used to determine the significance of the measurements between without vs. with visual EMG biofeedback. Posterior deltoid activity significantly decreased while infraspinatus activity and the infraspinatus/posterior activity ratio significantly increased during side-lying shoulder external rotation exercise with visual EMG biofeedback. This suggests that using visual EMG biofeedback during shoulder external rotation exercise is a clinically effective training method for reducing posterior deltoid activity and increasing infraspinatus activity.
authors.affiliation: Department of Physical Therapy, The Graduate School, Yonsei University, Won-ju, Republic of Korea.
authors.forename: One-Bin
authors.initials: OB
authors.lastname: Lim
authors.affiliation: Department of Physical Therapy, The Graduate School, Yonsei University, Won-ju, Republic of Korea.
authors.forename: Jeong-Ah
authors.initials: JA
authors.lastname: Kim
authors.affiliation: Department of Physical Therapy, The Graduate School, Yonsei University, Won-ju, Republic of Korea. ; Department of Physical Therapy, Seoul-chuk Hospital, Seoul, Republic of Korea.
authors.forename: Si-Jeong
authors.initials: SJ
authors.lastname: Song
authors.affiliation: Department of Physical Therapy, College of Health Science, Yonsei University, Won-ju, Republic of Korea.
authors.forename: Heon-Seock
authors.initials: HS
authors.lastname: Cynn
authors.affiliation: Department of Physical Therapy, College of Health Science, Yonsei University, Won-ju, Republic of Korea.
authors.forename: Chung-Hwi
authors.initials: CH
authors.lastname: Yi
keywords: EMG biofeedback; Infraspinatus; Posterior deltoid; Shoulder external rotation