Influence of the adaptation of lactate accumulation rate through physical training on muscle mass regulation

Skeletal muscle mass is regulated by the interaction of mechanical, metabolic, hormonal, and nutritional factors. Beyond contractile adaptations, training-induced changes in glucose metabolism and glycolytic enzyme activity may contribute substantially to muscle mass regulation. In this context, the lactate accumulation rate (vLa_peak) has recently gained attention as an indirect marker of glycolytic flux. This narrative review examines the potential relevance of training-induced vLa_peak adaptations for the regulation of skeletal muscle mass. Current evidence suggests that resistance training is able to adapt vLa_peak, likely reflecting enhanced glycolytic enzyme activity, greater recruitment of fast-twitch fibers, and sarcoplasmic adaptations associated with muscle hypertrophy. Ageing, inactivity, and disease are associated with declines in muscle mass, strength, and the activity of enzymes involved in anaerobic and aerobic metabolism, suggesting that reduced glycolytic capacity may contribute to impaired muscle quality. Although its clinical relevance for monitoring muscle mass remains insufficiently established, preliminary findings suggest that altered lactate accumulation characteristics may reflect impaired muscular metabolic capacity in chronic disease. Overall, vLa_peak appears to be a promising metabolic indicator of skeletal muscle adaptations relevant to muscle mass regulation. However, further longitudinal and mechanistic studies are needed to clarify its validity and clinical applicability.