Master of Science
Dr. Greg Marsh
No direct, quantitative, and non-invasive markers presently exist to assess exercise-induced muscle damage (EIMD). However, magnetization transfer ratios (MTR), an emerging measurement quantified via magnetic resonance imagery, provide more direct indication of muscle integrity following EIMD. This study compares and correlates the temporal pattern of the MTR to alternative indirect markers of EIMD in male vs. female populations, and subsequently establishes whether there are sex differences in biochemical activity during recovery. The antioxidant properties of estrogen hypothetically minimize muscle trauma, maintain membrane stability, and limit swelling resulting in heightened tissue integrity and resilience to EIMD. Six males and three females completed a standardized eccentric bicep preacher curl protocol of 10 sets of 10 reps (1 minute rest between sets) with 110% of the subjects MVC for a 3-second eccentric component. Joint angle, rate of perceived pain (RPP), maximum voluntary contraction (MVC), muscle cross-sectional area (CSA), transverse relaxation times (T2), and MTR were established at baseline prior to testing, and again at 0hr., 48hr., and 72hr. post EIMD. While joint angle and RPP revealed no significant changes, MVC saw significant decreases in men but not women (males: 84.16lbs ± 24.84lbs to 44.67lbs ± 16.58lbs; females: 55.15lbs ± 8.75lbs to 30.86lbs ± 5.24lbs). Mean male and female CSA increased without significance; however, significant differences were observed between the sexes at baseline and 48hr. Mean T2 relaxation times of the brachialis, medial, and lateral head of the bicep similarly experienced no significant increases within or between sexes (P>0.05). MTR additionally saw no statistical significance within or between males and females. In a recreationally-active population, our investigation concluded that estrogen has no significant effect on the maintenance of MVC post eccentric exercise, DOMs as determined by RPP, maintenance of joint angle, suppression of swelling as evaluated by CSA, or a decrease in changes in MTR or T2 times. While the study revealed little significance between participant groups, in the context of elite athletes and senescing populations, a minor increase in performance, even of only a few percent, could prove valuable.
Clausius Crawford, Nicholai Michael, "Degrees of Damage: Quantifying male vs. female exercise-induced muscle damage through magnetization transfer ratios" (2015). Electronic Thesis and Dissertation Repository. 3291.