Research Article
Lindsey J. Anderson
Abstract
Purpose: To determine whether exercise-induced muscle damage is altered under various premenopausal estrogen conditions. Methods: Muscle damage was compared during exogenous high (oral contraceptive; OC, N=3), endogenous high (luteal phase; HI, N=3), or endogenous/exogenous low (menses; LO, N=3) estrogen levels in young women. A muscle biopsy was obtained before and 2 hours after neuromuscular electrical stimulation (NMES). Gene expression was determined for IL-6, TNF-α, Gpx3, Mstn, MAFbx, MuRF-1, FOXO3a, and MyoD. Protein expression was determined for phosphorylated (P) and total (T) FOXO3a. Effect sizes (ES) and One-Way ANOVA compared means between groups. Results: Based on ES comparisons, NMES-induced increases in IL-6, TNF-α, MuRF-1, and MyoD were greatest in LO, Mstn decreases were blunted in OC, FOXO3a decreases were greatest in HI, and MAFbx decreased similarly across groups. There were no statistically significant between-group differences. There was a trend for decreased P-FOXO3a in HI (p=0.07). Conclusion: The smaller inflammatory response in HI and OC suggest an estrogen-related reduction in contraction-induced muscle damage. The robust MyoD response in LO may be evidence of a regenerative response being triggered after the muscle damage. Changes in estrogen condition did not influence acute atrogene mRNA or FOXO protein responses.