A landmark 47-year longitudinal study from Sweden’s Karolinska Institute has upended the conventional wisdom that fitness universally peaks around age 35. Researchers tracking 427 Swedish adults found markedly different trajectories across three physiological systems: women’s explosive leg power crests at 19, while men’s upper-body strength does not reach maximum until 36—a 17-year gap that underscores the inadequacy of one-size-fits-all fitness benchmarks.
The research identified distinct peaks for aerobic fitness (women at 31, men at 26) and muscular endurance (women at 34, men at 36), revealing that athletic performance follows sex-specific developmental and aging patterns rather than a single universal curve. Crucially, the study demonstrates that adults beginning regular exercise in their 30s, 40s, or 50s show measurable gains across all three fitness domains, suggesting that age-related decline is neither inevitable nor irreversible with consistent training.
Read the full article on GMJ Newsroom.
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