Coupling mechanisms between energy compensation and metabolic adaptation during high-intensity training in athletes:...

In this prospective longitudinal study, the authors investigated the mechanisms of coupling between energy compensation behaviors and metabolic adaptation in the course of a 48-week training cycle in 120 elite athletes stratified by sport type (endurance versus power/strength). Using energy compensation rate, multi-omics profiling, endocrine biomarkers, and gut microbiota composition in six measurement points from baseline to recovery phases, they found that energy compensation follows a characteristic U-shaped pattern, with nadirs of 79.6% and 82.6% in endurance and power/strength athletes at peak training load, reflecting persistent energy deficits amounting to 624-840 kcal/day. This energy deficit was accompanied by a coordinated suppression of leptin (effect size: - 1.9/- 1.4), an increase in cortisol (+ 1.7/+1.4), upregulation of pathways for fatty acid oxidation, and decreased Firmicutes-to-Bacteroidetes ratios. Systematic correlation analyses point to hierarchical patterns of coupling, according to which endocrine markers most closely related to energy status showed the highest association with compensation rate (leptin: r = 0.55; cortisol: r = - 0.46), whereas downstream phenotypes only express weaker associations. In subgroup analyses, greater metabolic perturbations were observed in athletes experiencing severe energy deficits (effect size: - 1.68 vs. - 0.72). These findings support an integrated "energy behavior-metabolic state" approach for personalized nutritional monitoring and intervention in high-performance sport.