Menstrual status and bone health in athletes from different sports - a retrospective analysis

Relative energy deficiency in sport (REDs) is linked to low energy availability, menstrual disturbances (MD) and low bone mineral density (BMD; Z-score < -1.0). The prevalence of these symptoms across sports and their interrelationships requires further investigation. This study aimed to 1) investigate the prevalence of severe MD and low BMD among athletes from different sports, 2) compare BMD Z-scores at lumbar spine, total hip and whole-body between regularly menstruating (RM), severe MD and hormonal contraceptive (HC) users, and 3) examine factors related to BMD among endurance athletes, including menstrual status, athletic caliber and sport-specific loading characteristics.

Retrospective analysis of cross-sectional data from seven projects included 411 women from 34 sports (endurance: n = 257; non-endurance: n = 154). BMD was assessed using dual-energy X-ray absorptiometry. Menstrual status was defined by the three-step method, cycle tracking or questionnaire, and categorized as RM, severe MD or HC. Endurance sports were further grouped by loading characteristics (very low, low and medium).

Among non-HC users (51%), the prevalence of severe MD was 37% in endurance, 34% in ball sport and 36% in power- and technical- sports. BMD was not different between menstrual status groups at either lumbar spine (P = 0.334), total hip (P = 0.079) or whole-body (P = 0.164). Endurance athletes had lower lumbar spine BMD Z-scores than non-endurance athletes (-0.0 ± 1.0 vs 1.2 ± 1.2, P < 0.0001), with a higher prevalence of low BMD (17% vs 2%, P = 0.015). Total hip BMD Z-scores were lower in endurance than non-endurance athletes (0.6 ± 0.9 vs 1.4 ± 1.2, P < 0.05 for age < 27). Among endurance athletes, neither loading characteristics nor athletic caliber were associated with BMD. However, endurance athletes with severe MD had lower total hip BMD Z-scores compared to RM athletes (P = 0.008) and HC users (P = 0.021).

The prevalence of severe MD did not differ between sport types. Overall, BMD Z-scores did not differ across menstrual status categories. However, endurance athletes had lower BMD, with total hip BMD being lower in those with severe MD. Heterogenous menstrual assessment methods across the projects included in this study may have impacted the results. Future research should integrate comprehensive REDs assessments including detailed data on menstrual status, training history, bone-loading impact and injuries in female athletes from different sports.