Sex Dimorphism in Muscle Damage-induced Inflammation

Introduction The purpose of this study was to determine the effect of resistance exercise (RE)-induced hormonal changes on intramuscular cytokine gene expression after muscle damage in untrained men and women. Methods Men (n = 8, 22 ± 3 yr) and women (n = 8, 19 ± 1 yr) completed two sessions of 80 unilateral maximal eccentric knee extensions followed by either an upper body RE bout (EX) or a time-matched period (CON). Muscle samples (vastus laterals) were analyzed for mRNA expression of interleukin (IL) 6, IL-10, IL-15, TNFA, TGFB, CCL2, and CD68 at PRE, 12 h, and 24 h after the session. Results A significant time-sex-condition interaction was found for TGFB with an increase for EX in men at 12 h from PRE. For EX, TGFB was also greater in men than in women at 12 and 24 h. Significant time-sex and condition-sex interactions were found for IL-10 with an increase for men that was greater than for women at 12 and 24 h. IL-10 was lower in EX than CON for men. A significant time-sex interaction was found for TNFA with an increase for men that was greater than for women at 24 h. A significant time-condition interaction was found for CD68 with an increase at 12 h and decrease at 24 h for EX and CON. CD68 was lower in EX than CON at 12 h. A significant time effect was found for IL6 and CCL2 with an increase at 12 and 24 h. Conclusions Results suggest that women seem to have a muted intramuscular cytokine (i.e., IL-10, TNF-a, and TGF-ß) response to muscle damage compared with men.