Within-Day Energy Deficiency and Metabolic Perturbation in Male Endurance Athletes

Endurance athletes are at increased risk of relative energy deficiency associated with metabolic perturbation and impaired health. We aimed to estimate and compare within-day energy balance (WDEB) in male athletes with suppressed and normal resting metabolic rate (RMR) and explore if within-day energy deficiency (WDED) is associated with endocrine markers of energy deficiency. Thirty-one male cyclists, triathletes, and long-distance runners recruited from regional competitive sports clubs were included. The protocol comprised measurements of RMR by ventilated hood, and energy intake and energy expenditure to predict RMRratio (measured RMR/predicted RMR), energy availability (EA), 24-hour energy balance (EB) and WDEB in 1-hour intervals, assessment of body-composition by dual-energy X-ray absorptiometry, and blood plasma analysis. Subjects were categorized as having suppressed (RMRratio 0.90, n=11). Despite no observed differences in 24-hour EB or EA between the grou...