Risk factors associated with stress reactions in female Marines

Women have a higher stress fracture rate than men in military studies, although the exact cause of this is not clear. Hyperpronation has been implicated as a potential risk factor for injury. In this prospective observational study, we measured subtalar joint range of motion in 101 women (ages 20-27 years) enrolled in Marine Corps Officer Candidate School in June 1994. The purpose of this study was to identify risk factors for injury in female Marine Corps officer candidates. The primary area of interest was the association between the amount of subtalar joint range of motion and stress reactions. Questionnaires were administered that explored previous physical activities, sports participation, and menstrual history. Anthropometric measurements were performed, including subtalar joint range of motion. During the 10 weeks of physical training, 11.5% of the women (N = 12) had stress reactions compared with 7% of the men (N = 10). There was no statistically significant difference in the means of subtalar joint range of motion in the stress reaction group compared with the non-stress reaction group. Differences in stress reaction rate across quartiles of subtalar joint range of motion were not significant. Those women who ran fewer miles (< or = 2.8 miles per session) before training had a higher rate of stress reactions (p < 0.04). Younger individuals (< 23 years) had a higher rate of stress reactions (p < 0.01). Women with fewer menstrual periods (< 10 per year) had a higher rate of stress reactions (p < 0.02). A narrow pelvis (< or = 26 cm) was associated with a higher rate of stress reactions (p < 0.09). We conclude that an increased subtalar joint range of motion is not a risk factor for stress reactions in women. However, further studies with a larger study population should be performed to confirm these findings.