Relative Energy Deficiency in Sport (RED-S) among Norwegian male athletes. Energy availability, health, and performance among male athletes at different age and performance levels

Abstract

Relative Energy Deficiency in Sport (RED-S) is a syndrome where low energy availability (LEA) has a negative impact on health [e.g., endocrine and metabolic alterations, reproductive dysfunction, impaired bone mineral density (BMD)] and performance. In females, the development and prevalence of RED-S have been well-investigated. However, research on males of all ages and performance levels is lacking. The overall aim of this dissertation was therefore to investigate RED-S among Norwegian male athletes at different age and performance levels. Three independent studies have been performed, and three original papers are included in this dissertation. The aims of Studies I and II were to investigate RED-S in well-trained and Olympic-level adult athletes, whereas Study III investigated RED-S among adolescent athletes attending elite sport high schools. Study I investigated how a four-week intensified endurance training period specifically designed to increase aerobic performance would affect markers of RED-S, including resting metabolic rate (RMR), body composition and bone health, energy intake (EI), and metabolic and endocrine markers in well-trained cyclists. Study II investigated the prevalence of surrogate RED-S markers in a cohort of Norwegian Olympic-level athletes using similar markers as in Study I, including RMR, body composition, bone health, and altered metabolic and endocrine markers. Study III investigated RED-S in adolescent endurance athletes attending Norwegian elite sport high schools over a three-year period, with special attention to bone health, energy availability (EA), RMR, as well as aerobic performance and muscular strength.