Factors Relating to Gender Specificity of Unloading-Induced Declines in Strength

Michael R. Deschenes, William & Mary
Raymond W. Mccoy, William & Mary
Katherine A. Mangis, William & Mary

Abstract

Introduction: This investigation aimed to: (1) confirm whether women were more vulnerable to the negative neuromuscular adaptations elicited by muscle unloading and if so, (2) determine which physiological mechanism(s) explain those gender-related differences. Methods: Healthy young men (20.7 +/- 0.3 years) and women (20.3 +/- 0.3 years)-(N = 12/group)-participated by completing neuromuscular functional tests before and after 7 days of unloading. Results: During isokinetic testing of peak torque, work performed, and power, women displayed significantly (P <= 0.05) greater declines in performance than men at 1.05 and 2.09, but not 0.53 rads/s. During maximal isometric contractions, women experienced greater strength decrements. Similar gender-specific adaptations to unloading were found in EMG activity, but not muscle mass, neuromuscular transmission, or force relative to EMG. Conclusions: Women are more susceptible to the adaptations of muscle unloading, and disturbances in neural drive from the central nervous system are probably responsible. Muscle Nerve 46: 210-217, 2012