title: Differences in the activation and co-activation ratios of the four subdivisions of trapezius between genders following a computer typing task.
abstract: The aim of this study was to provide a description of gender differences of the activation patterns of the four subdivisions of the trapezius (clavicular, upper, middle, lower) following a 60min computer work task. Surface EMG was collected from these subdivisions from 21 healthy subjects during bilateral arm elevation pre-/post- task. Subjects completed a standardized 60min computer work task at a standard, ergonomic workstation. Normalized activation and activation ratios of each trapezius subdivision were compared between genders and condition with repeated measures ANOVAs. The interaction effect of Gender×Condition for upper trapezius% activation approached significance at p=0.051with males demonstrating greater activation post-task. The main effect of Condition was statistically significant for% activation of middle and lower trapezius (p<0.05), with both muscles demonstrating increase activation post-task. There was a statistically significant interaction effect of Gender×Condition for the Middle Trapezius/Upper Trapezius ratio and main effect of Condition for the Clavicular Trapezius/Upper Trapezius ratio, with a decreased ratio post-typing. Gender differences exist following 60min of a low force computer typing task. Imbalances in muscle activation and activation ratios following computer work may affect total shoulder kinematics and should be further explored.
authors.affiliation: Department of Occupational Therapy, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, United States. Electronic address: szucsk@duq.edu.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Szucs
authors.affiliation: Mahoning County Educational Service Center, 100 Debartolo Place #220, Youngstown, OH 44512, United States. Electronic address: m.molnar@mahoningesc.org.
authors.forename: Megan
authors.initials: M
authors.lastname: Molnar
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D003201:Computers; D004576:Electromyography; D016552:Ergometry; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D012727:Sex Characteristics; D012782:Shoulder / Q000502:physiology; D012785:Shoulder Joint / Q000502:physiology; D064171:Superficial Back Muscles / Q000502:physiology*; D055815:Young Adult
keywords: Compartments; Computer work; Muscle activity; Trapezius