47-year study: physical fitness starts declining around 35
A Swedish study that followed the same 427 people from age 16 to 63 saw fitness, endurance and muscle power begin to decline around 35, even among people who exercised.
Source: A 47-year study reveals the age when your body starts losing strength (sciencedaily.com). Summary written with AI from the source and reviewed by rules; read the original.
What the research shows
The Karolinska Institutet's SPAF study repeatedly assessed men and women born in 1958. Aerobic capacity and muscle endurance peaked between ages 26 and 36. The decline started modestly and sped up with age: by 63, average performance was 30% to 48% below peak, with a similar pattern in both sexes.
People who started exercising in adulthood improved physical capacity by about 5% to 10%. A follow-up study of the same group found that better aerobic fitness at 34 and 52 was linked to less arterial stiffness at 63.
What it means
Exercise did not stop the age-related decline, but it helped people stay at a higher level. According to the lead author, it is never too late to start moving.
How to read it with care
The peak is a population average: each person can still improve with training after 35. The link with arteries is an association and does not prove that fitness prevented stiffening.
This article explains research and does not replace a consultation. Anyone thinking about changing exercise, diet, supplements or treatment should talk to a doctor or another qualified health professional.