Low Energy Availability, Menstrual Status, And Skeletal Health In Sportswomen

Cross-country and track and field (XT) sportswomen are at elevated risk for the Female Athlete Triad which is characterized by low energy availability (LEA), menstrual cycle dysfunction, and impaired skeletal health. Hormonal contraceptives are often prescribed (HC), but how this influences bone and what factors are most protective is still debated. PURPOSE: To compare bone health and key factors associated with LEA and menstrual cycle dysfunction in athletes and physically active matched Controls. METHODS: Collegiate XT (n = 32) and Controls (n = 21) were grouped by menstrual status: natural and normal cycle (NM); natural but infrequent/absent cycle (NMI/A); HC users (HC) and risk of LEA based on kcal/kgLM/day: ≤30 (high) or > 30 (low). All participants completed training, injury, sleep, menstrual, and dietary questionnaires followed by Dual-energy X-ray Absorptiometry scans. One-way analysis of variances were used for group comparisons with Cohen’s (d) and α = 0.05. RESULTS: Menstrual groups had similar bone injury/health and lean mass measures; however, HC users had greater fat measures and NMI/A had a higher calcium intake than NM (all p ≤ 0.04, d = 0.6-1.4). In XT only, HC users had better lumbar spine density than NMI/A (p = 0.015, d = 1.2), despite similar anthropometrics, training, bone injuries, and sleep and dietary quality. High-risk LEA had greater lean mass and bone measures than low-risk (p ≤ 0.049, d = 0.8-1.4) which were further exacerbated at all sites after controlling for total lean mass (p ≤ 0.005, d = 0.03-1.4). However, these high-risk women were in a greater caloric deficit (p < 0.001, d = 2.8) and, although not statistically significant, had double the number of reported bone injuries than the low-risk LEA group which could have clinical significance. CONCLUSIONS: These data highlight the complex interplay between skeletal health, menstrual status, use of HCs, and LEA risk and the need for more individualized screening tools. In addition, this study provides evidence that first, HC use may be skeletally protective; second, extra calcium intake may protect bone mass in women with disrupted menstrual cycles; and third, there is a disconnect between bone injury incidence is this cohort and DXA-derived skeletal attributes; suggesting all of which may be important interventional targets for at-risk females.