Limited reproducibility of individual physiological adaptations to repeated endurance exercise training.

Journal of applied physiology (Bethesda, Md. : 1985)·July 1, 2026·PMID 42241643

Why it matters

Clinicians and coaches often assume that a person's response to exercise training is consistent, but this study shows that even under highly controlled conditions, individual adaptations fluctuate substantially between identical training blocks. This challenges the use of a single training response to classify someone as a 'responder' or 'non-responder' and has implications for personalized exercise prescription and performance prediction.