ENERGY AVAILABILITY: PREVALENCE AND IMPACT ON ENDOCRINE STATUS AND BONE HEALTH IN MALE ENDURANCE TRAINED ATHLETES

Introduction: Relative Energy Deficiency in Sport (RED-S) is based on the assumption that low energy availability (EA) is responsible for deficiencies in multiple physiologic systems. The Exercise-Hypogonadal Male Condition (EHMC) shares similar symptomology with RED-S, including diminished sex steroid hormone levels and decreased bone mineral density (BMD), but whether EA plays a causative role and how prevalent low EA is in male athletes are unclear. Studies have provided evidence that EHMC and RED-S are more likely to develop in endurance athletes performing high volumes of training, but a definitive cause remains unknown. Therefore, it is important to conduct an investigation into prevalence and the potential cascade of events in male endurance trained athletes (META) with respect to EA. Purpose: A two-phase research project investigated prevalence of low EA (study 1) and possible associations between EA and risk factors for RED-S – EHMC (study 2) in META. Methods: Study 1 participants completed an online descriptive survey and 3-day diet and training records. Study 2 measured laboratory assessments for resting metabolic rate (RMR), bone mineral density (BMD), blood draw for biomarkers. EA was calculated to determine prevalence of low EA risk and conduct correlations between EA and RMR, BMD, reproductive, metabolic and bone biomarkers. Results: This sample demonstrated 47.2% (n=51) as At Risk (0.33) or between EA and any hormonal or blood bone bio-markers (p>0.150). Conclusions: Major findings were the high prevalence of low EA, and weak, negative associations between EA and both RMR and BMD with no association between EA and any reproductive, metabolic or bone blood biomarkers. These findings question the validity of cut-points developed in females for use in men. Identifying male specific EA thresholds is an important step to determine the implications not only on hormonal disruption, metabolism and bone health, but to guide future research for RED-S – EHMC.Doctor of Philosoph