Study finds peak physical ability around age 35, mirroring elite athletes

A long-running study by researchers at the Karolinska Institute finds that physical ability peaks around age 35, with performance decline accelerating after about 40. The findings help explain why many elite athletes reach top levels in their mid-30s, including basketball star LeBron James and tennis great Serena Williams.

The 47-year longitudinal study began in 1974 with 222 men and 205 women who were 16 years old at enrollment. Over the next four decades, participants completed regular tests of aerobic capacity, muscular endurance and muscular power. Aerobic capacity was assessed through cycling or running tests, muscular endurance through a bench press test, and muscular power via a leg jump test.

Analyses showed that women reached peak aerobic capacity at 35, while men peaked at 36. For muscular endurance, women peaked at 34 and men at 36. Muscular power peaked earlier, with men at 27 and women at 19, highlighting different timelines for explosive strength compared with endurance and aerobic capacity.

Overall, the researchers concluded that peak capacity occurs before 36 and after roughly 40 there is a similar and accelerating decline in all capacities for both sexes. On average, physical capacity declined 37% from peak to age 63, with a range of 30% to 48% across individuals. The findings align with patterns seen in many sports, where top athletes tend to reach their peak in the mid-30s.

The study, published in the Journal of Cachexia, Sarcopenia and Muscle, notes that even elite athletes who exercise regularly continue to experience functional losses with age. Lead author Maria Westerstahl said, “It is never too late to start moving,” adding that the study shows physical activity can slow the decline in performance, even if it cannot completely stop it. The researchers plan to explore the mechanisms behind why peak performance occurs around age 35 and why activity slows but does not halt the decline.

The timing of peak performance mirrors anecdotes across several sports. In football, Luka Modrić won the 2018 Ballon d’Or at 33, while Didier Drogba’s iconic Champions League Final goal came at 34. In tennis, Roger Federer won Grand Slams around ages 35–36, and Serena and Venus Williams had peaks in their mid-thirties. In basketball, LeBron James’s 2019–2020 season—a championship-winning year—came at age 35. These examples align with the study’s broader finding that mid-30s often mark a high-water mark for physical capacity.

Experts caution that while regular activity can slow deterioration, aging physiology imposes limits. The researchers emphasize that the results should inform training, health messaging and expectations for athletes and the wider public as life expectancy and activity patterns evolve. Future work will aim to identify the biological mechanisms driving the observed timelines and to determine how best to sustain physical function across adulthood.