Response of testosterone to prolonged aerobic exercise during different phases of the menstrual cycle.

PURPOSE: To examine the androgen response to exercise in women under conditions of high (H) and low (L) estrogen (E2) levels. METHODS: Ten exercise trained eumenorrheic women (mean ± SD: 20.0 ± 2.2 years, 58.7 ± 8.3 kg, 22.3 ± 4.9 % body fat, VO2max = 50.7 ± 9.0 mL/kg/min) completed a 60 min treadmill run at ~70 % of VO2max during both the mid-follicular (L-E2, 69.7 ± 7.3 % VO2max) and mid-luteal (H-E2, 67.6 ± 7.9 % VO2max) phases of their menstrual cycle. Blood samples were taken pre-exercise (PRE), immediately post (POST), and 30 min into recovery (30R) from exercise and analyzed for total testosterone using ELISA assays. Results were analyzed using repeated measures ANOVA. RESULTS: Testosterone responses were (mean ± SD: L-E2, pre = 1.41 ± 0.21, post = 1.86 ± 0.21, 30R = 1.75 ± 0.32 nmol/L; H-E2, pre = 1.27 ± 0.23, post = 2.43 ± 0.56, 30R = 1.69 ± 0.34 nmol/L). Statistical analysis indicated no significant interaction existed between high and low estrogen conditions across the blood sampling times (p = 0.138). However, a main effect occurred for exercise (p < 0.004) with the post-testosterone concentration being greater than pre, although pre vs. 30R was not different (p > 0.05). All testosterone hormonal concentrations immediately post-exercise greatly exceeded the level of hemoconcentration observed during the L-E2 and H-E2 exercise sessions. CONCLUSIONS: Prolonged aerobic exercise induces short-term elevations in testosterone in trained eumenorrheic women, which appears unrelated to estrogen levels and menstrual cycle phase. These increases may occur due to either increased androgen production and/or decreased degradation rates of the hormone, and are not solely the result of plasma fluid shifts from the exercise.

Sex differences in musculoskeletal injury epidemiology and subsequent loss of tactical readiness during Marine Corps Officer Candidates School.

INTRODUCTION: The US Marine Corps (USMC) Officer Candidates School (OCS) is a 10-week training course for Marine Officer Candidates (MOCs). OCS training is rigorous and demanding, which results in a high risk of musculoskeletal injuries (MSIs). The objective of this analysis was to describe MSIs among women and men during the USMC OCS at Quantico, Virginia, from September 2020 to November 2021. METHODS: This prospective cohort study assessed MSIs that occurred among 736 MOCs (women: 17.8% of sample, men: 82.2%). Data for the study were derived from routinely collected injury data by athletic trainers and physical therapists embedded within the training units. Injury incidence, event at the time of injury occurrence, anatomic location, injury type and disposition following injury were described. Fisher's exact tests were used to compare proportions of injured women and men. RESULTS: The cumulative injury incidence was higher among women (39.7%) compared with men (23.1%, p<0.001). When specific events associated with injuries were reported, most frequent events were the obstacle course (women: 20.9% of injuries, men: 12.9%) and the conditioning hike (women: 11.6%, men: 6.9%). Most injures affected the lower body (women: 67.4%, men: 70.8%). The most frequent body part injured was the lower leg (18.6%) in women and the knee (23.3%) in men. The most frequent injury type was strain (women: 39.5%, men: 24.3%), followed by sprain (women: 16.3%, men: 14.9%). A greater percentage of female (92.3%) compared with male MOCs (69.3%; p<0.001) were assigned light duty status following MSIs. CONCLUSIONS: Mitigation of injuries during OCS events such as the obstacle course and the conditioning hike needs further investigation. The high risk of overuse lower leg injuries among women and the higher incidence of injuries among women compared with men underscore the need for further investigation of modifiable sex-specific injury risk factors.