Human study · Exercise · 14 Oct 2026
A 47-year study found fitness starting to fall around age 35
Source: ScienceDaily
What the research found
ScienceDaily reported on 14 October 2026 a Karolinska Institutet follow-up of the Swedish Physical Activity and Fitness study, published in the Journal of Cachexia, Sarcopenia and Muscle. The same 427 men and women, born in 1958, were measured from age 16 to 63. Aerobic fitness and muscular endurance generally peaked between 26 and 36, and average performance was about 30 to 48 percent below peak by age 63. Decline rates were similar in men and women. People who became active in adulthood gained about 5 to 10 percent in physical capacity, but activity did not erase the age pattern. A 2026 Scientific Reports paper on the same cohort linked better aerobic fitness at 34 and 52 with less arterial stiffness at 63, after accounting for obesity, smoking, and blood pressure. That link is not proof of cause. Not medical advice.
Evidence level: Human study. A study in people, but an association isn't proof of cause.
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