Assessing Risk Factors For Relative Energy Deficiency In Sport In Female Ultramarathon Trail Runners

PURPOSE: We provide a descriptive report of bone mineral density (BMD), biomarkers of metabolic and reproductive health, injury characteristics, nutrition habits, and risk level for Relative Energy Deficiency in Sport (REDs) among naturally menstruating female athletes competing in a 100-mile trail running race. METHODS: Ultramarathon runners participating in the Western States 100-mile Endurance Run were enrolled in the study. Naturally menstruating females not on hormonal contraception were selected for this sub-analysis. Participants were surveyed on topics including menstrual cycle, injury history, mental health, and nutrition. BMD was assessed using dual x-ray absorptiometry at the femoral neck, distal radius, total hip, lumbar spine, and whole body. Biomarkers were assessed pre-race via venous blood draw and included free triiodothyronine (free T3), total cholesterol, LDL, and ferritin. Athletes were categorized into REDs risk level using the REDs Clinical Assessment Tool 2. Results were analyzed using descriptive statistics. RESULTS: Eleven naturally menstruating female athletes (age 39 ± 4 years, height 166.48 ± 4.72 cm, weight 61.01 ± 8.22 kg) were grouped into two REDs risk levels (green, n = 8; yellow, n = 3). Table 1 presents participant characteristics for each risk level, including menstrual cycle and injury characteristics. Free T3 (mean: 3.44 pg/mL) was in normal range for all participants (2.3 - 4.2 pg/mL). Mean ferritin was 29.2 ng/mL, below the recommended level for female athletes (>35 ng/mL). Mean BMD z-scores were normal (> -1.0) at all sites. Only one participant had a BMD z-score < -1.0 at any measured site. CONCLUSION: The overall risk for REDs was low in this cohort of female ultramarathon runners. However, ferritin levels were below the reference range, which may impact performance. This study is underpowered to draw more definitive conclusions. Supported by: Wu Tsai Human Performance Alliance