Resting metabolic rate for energy availability assessment in high-performance sports

Abstract

Annotation. Low energy availability is the primary factor contributing to the development of Relative Energy Deficiency Syndrome in sports (RED-S), leading to a disruption of various bodily functions. Evaluating energy availability plays a crucial role in preventing this syndrome. Traditionally, energy availability assessment involves tracking calorie intake from food and energy expenditure during physical activity. However, this approach may lack precision, especially when relying on athletes’ self-reported data through food and activity diaries. Researchers are exploring potential biomarkers to gauge energy availability, which has sparked scientific interest. This study aims to investigate the feasibility of using basal metabolism to assess energy availability in athletes. Based on the PubMed database, a retrospective analysis of scientific publications on the topic of the study was performed, choosing either the most recent publications (over the last 5 years) or publications on this issue, regardless of age. Resting metabolic rate refers to the minimum energy required for a person's vital functions while at rest. Skilled athletes usually exhibit a higher basal metabolic rate compared to untrained individuals, but it may decrease after intense training periods, indicating a slowdown in metabolic reactions and potential increase in catabolic processes. During intense training, the body’s energy demands rise, and if not adequately compensated by the diet, it triggers a series of metabolic, hormonal, and nervous reactions to maintain homeostasis and conserve energy. Numerous studies have revealed a correlation between reduced resting energy expenditure and low energy availability. Consequently, a decrease in basal metabolism could serve as a valuable biomarker for assessing energy availability, especially during long-term monitoring. The most accurate method for determining basal metabolism in sports practice is indirect calorimetry. However, its accuracy requires standardized conditions, including a controlled training regime before measurements and accounting for the menstrual cycle phase in female athletes. Further investigation into energy availability biomarkers will enable more objective assessments of its presence and aid in identifying athletes at risk of developing RED-S syndrome.