Haruthai Petviset, Prasert Sakulsriprasert, Mantana Vongsirinavarat, and Peemongkon Wattananon

DOI: 10.14456/sjst-psu.2021.68

pp. 512 - 519

Abstract

This is a cross-sectional study that aimed to compare upper trapezius (UT), middle trapezius (MT), lower trapezius
(LT), and serratus anterior (SA) muscle onset, deactivation, and activation time from surface electromyography (sEMG) in
shoulder flexion, scaption, and abduction between the inferior angle type of scapular dyskinesis (ISD) group (n = 6) and normal
pattern of scapular motion (NP) group (n = 6). An independent t-test was used for statistical analysis. In flexion, early MT and
LT deactivation time were found, and MT activation time in the ISD was shorter than the NP (p < 0.05). In scaption, early LT,
and SA deactivation time were found in the ISD (p < 0.05). In abduction, UT deactivation and activation time were significantly
different between groups (p < 0.05). This study demonstrated the early time of muscle deactivation and shorter muscle activation
time of the scapular force couple muscles. Therefore, the active scapular control should be emphasized during shoulder elevation.