Fitness Peaks Earlier in Life Than You Might Think — but Now There’s Good News for Older People

If you’re over 35 and have noticed that your morning jog feels a bit harder than it used to, you’re not imagining things.

A recently published Swedish study spanning nearly five decades has confirmed what many of us suspected: Our bodies start their slow decline earlier than we’d like to admit.

But before you resign yourself to a life on the couch, there is a silver lining that makes the research worth celebrating.

What the researchers found

Researchers at Sweden’s Karolinska Institutet followed hundreds of randomly selected men and women for 47 years — from age 16 to 63 — and regularly measured their fitness, strength and muscle endurance.

The findings revealed that physical capacity peaks at age 35, after which fitness and strength begin their gradual descent, regardless of how much you exercise. This deterioration accelerates as the years pass, affecting everyone from weekend warriors to dedicated gym-goers.

The Swedish Physical Activity and Fitness (SPAF) findings were published in the Journal of Cachexia, Sarcopenia and Muscle.

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The encouraging discovery

On a brighter note, the researchers found that people who become physically active in adulthood see their physical capacity improve by 5% to 10%. While exercise can’t completely halt the aging process, it significantly slows the decline in performance.

In a summary of the study findings, lead author Maria Westerståhl –a lecturer at the Department of Laboratory Medicine — says:

“It is never too late to start moving. Our study shows that physical activity can slow the decline in performance, even if it cannot completely stop it.

The research team is now investigating why everyone peaks at 35 and exploring the biological mechanisms behind why physical activity slows — but doesn’t entirely prevent —performance loss.

The study is continuing, with participants scheduled for another round of examinations next year at age 68. Researchers plan to connect changes in physical capacity with lifestyle factors, overall health and biological mechanisms, potentially unlocking new strategies for healthy aging.