Long-Term Study Finds Fitness Levels Fall Off After Age 35

A decades-long study from Sweden shows physical performance begins deteriorating after 35, regardless of training history. However, regular exercise can help slow the decline

When it comes to physical fitness, the old adage “use it or lose it” is sound advice, especially according to new research.

Peak physical performance starts to decline as soon as age 35, according to the Swedish Physical Activity and Fitness study conducted at Karolinska Institutet.

Researchers followed 427 men and women born in 1958, from age 16 to 63 to track how their physical fitness abilities changed over time. They found that people hit their fitness peak before 35 and decline from there, regardless of how much people worked out at younger ages and even among those who maintained continuous training.

Over the years, researchers tracked both the participants’ physical activity levels, seeing steady progress through the teens and 20s. They then continually measured how well participants performed different exercises to gauge muscular endurance, power and aerobic capacity, with exercises including bench presses, a vertical jump test and cycling for at least 10 minutes.

While the average fitness peak was at 35, men and women only started to see declining aerobic endurance at age 45, while women started to lose muscular power before men, as early as age 32.

Interestingly, the authors found that women’s muscular power — using the vertical jump test — peaked at age 19, while men’s peak at age 27.

The overall decline in physical capacity from peak to age 63 ranged from 30% to 48%, with the rate of decline starting slowly, decreasing at 0.3% to 0.6%per year and accelerating to 2.0% to 2.5% per year in both men and women.

Despite the measurable — and unavoidable — decline in physical fitness, researchers observed that the sooner people started exercising as an adult, the better their performance outcomes were. 

Those who were more active from age 16 and onward into adulthood had the highest performance across all exercises.