title: Comparing trapezius muscle activity in the different planes of shoulder elevation.
abstract: [Purpose] The purpose of this study was to compare the upper, middle, and lower trapezius muscles' activity in the different planes of shoulder elevation. [Subjects] Twenty male subjects volunteered for this study. [Methods] Surface electromyographic (EMG) activity for each of the three regions of the trapezius muscles in the three different planes of elevation were collected while the participants maintained 30, 60, and 90 degrees of elevation in each plane. The EMG data were normalized with maximum voluntary isometric contraction (%MVIC), and compared among the planes at each angle of elevation. [Results] There were significantly different muscle activities among the elevation planes at each angle. [Conclusion] This study found that the three regions of the trapezius muscles changed their activity depending on the planes of shoulder elevation. These changes in the trapezius muscles could induce appropriate scapular motion to face the glenoid cavity in the correct directions in different planes of shoulder elevation.
authors.affiliation: Graduate School of Health Sciences, Hokkaido University, Japan ; Matsuda Orthopedic Memorial Hospital, Japan.
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Ishigaki
authors.affiliation: Graduate School of Health Sciences, Hokkaido University, Japan ; Hokushin Hospital, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Ishida
authors.affiliation: Faculty of Health Sciences, Hokkaido University, Japan.
authors.forename: Mina
authors.initials: M
authors.lastname: Samukawa
authors.affiliation: Faculty of Health Sciences, Hokkaido University, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Saito
authors.affiliation: Graduate School of Health Sciences, Hokkaido University, Japan.
authors.forename: Motoki
authors.initials: M
authors.lastname: Hirokawa
authors.affiliation: Matsuda Orthopedic Memorial Hospital, Japan.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Ezawa
authors.affiliation: Matsuda Orthopedic Memorial Hospital, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Sugawara
authors.affiliation: Faculty of Health Sciences, Hokkaido University, Japan.
authors.forename: Harukazu
authors.initials: H
authors.lastname: Tohyama
authors.affiliation: Faculty of Health Sciences, Hokkaido University, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Yamanaka
keywords: EMG; Plane of shoulder elevation; Trapezius muscle