Stressor-Induced Increase in Muscle Fatigability of Young Men and Women is Predicted by Strength but Not Voluntary ActivationJournal of Applied Physiology
Format of Original12 p.
PublisherAmerican Psychological Association
Original Item IDdoi: 10.1152/japplphysiol.01129.2013
AbstractThis 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.
Citation InformationManda L. Keller-Ross, Hugo M. Pereia, Jaclyn Pruse, Tejin Yoon, et al.. "Stressor-Induced Increase in Muscle Fatigability of Young Men and Women is Predicted by Strength but Not Voluntary Activation" Journal of Applied Physiology (2014) ISSN: 0021-8987
Available at: http://works.bepress.com/kristy_nielson/25/