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Stressor-induced increase in muscle fatigability of young men and women is predicted by strength but not voluntary activation.
Keller-Ross-ML; Pereira-HM; Pruse-J; Yoon-T; Schlinder-Delap-B; Nielson-KA; Hunter-SK
J Appl Physiol 2014 Apr; 116(7):767-778
This study investigated mechanisms for the stressor-induced changes in muscle fatigability in men and women. Participants performed an isometric-fatiguing contraction at 20% maximal voluntary contraction (MVC) until failure with the elbow flexor muscles. Study one (n = 55; 29 women) involved two experimental sessions: 1) a high-stressor session that required a difficult mental-math task before and during a fatiguing contraction and 2) a control session with no mental math. For some participants (n = 28; 14 women), cortical stimulation was used to examine mechanisms that contributed to muscle fatigability during the high-stressor and control sessions. Study two (n = 23; nine women) determined the influence of a low stressor, i.e., a simple mental-math task, on muscle fatigability. In study one, the time-to-task failure was less for the high-stressor session than control (P < 0.05) for women (19.4%) and men (9.5%): the sex difference response disappeared when covaried for initial strength (MVC). MVC force, voluntary activation, and peak-twitch amplitude decreased similarly for the control and high-stressor sessions (P < 0.05). In study two, the time-to-task failure of men or women was not influenced by the low stressor (P > 0.05). The greater fatigability, when exposed to a high stressor during a low-force task, was not exclusive to women but involved a strength-related mechanism in both weaker men and women that accelerated declines in voluntary activation and slowing of contractile properties.
Humans; Men; Women; Muscles; Fatigue; Musculoskeletal-system; Muscle-tension; Muscle-stress; Muscle-physiology; Physiology; Physiological-effects; Physiological-function; Physiological-fatigue; Mental-processes; Sex-factors; Age-factors; Age-groups; Author Keywords: gender; muscle fatigue; sex differences; transcranial magnetic stimulation; voluntary activation
M. L. Keller-Ross, Dept. of Cardiovascular Diseases, Mayo Clinic and Foundation, 200 First St., S.W., Rochester, MN 55901
Issue of Publication
Agriculture, Forestry and Fishing
Journal of Applied Physiology
University of Illinois at Chicago
Page last reviewed: November 8, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division