Affiliations: School of Kinesiology and Health Science, York University, Toronto, ON, Canada
Correspondence:
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Corresponding author: Janessa D.M. Drake, 2030 Sherman Health Science Research Centre School of Kinesiology and Health Science, Faculty of Health, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada. Tel.: +1 416 736 2100 (Ext. 33568); E-mail: jdrake@yorku.ca.
Abstract: BACKGROUND: Chest size is a known factor in the development of back pain for women. However, the neuromuscular mechanisms associated with chest size and back pain are poorly understood. OBJECTIVE: The purpose of this study was to investigate chest size and its association with back pain development and muscle activity patterns during prolonged standing. METHODS: Twenty university-aged women were divided into two groups: small chest size (n= 10, ∼A/C cup) and large chest size (n= 10, ∼D/E cup). Participants completed a 2-hr standing protocol, where eight channels of bilateral trunk electromyography were collected. Muscle activity, specifically co-contraction, was compared between chest size groups, pain developers, and time. RESULTS: The large chest size group reported higher amounts of pain at the upper, middle, and low back. Women in the large chest group sustained higher levels of co-contraction for muscles involving the thoracic and lumbar erector spinae compared to those in the small chest size group during prolonged standing. CONCLUSIONS: Thoracolumbar co-contraction determined in this study may be a potential mechanism contributing to increased back pain development for women with large chest sizes during prolonged standing. This pain mechanism could be targeted and addressed in future non-invasive musculoskeletal rehabilitation to improve back pain for women.
Keywords: Anthropometry, low back pain, occupational standing, muscle co-contraction
