A 47-year longitudinal study from Sweden reveals that physical fitness and strength begin to decline around age 35, regardless of prior exercise habits. However, the research highlights that starting physical activity later in life can still boost capacity by 5 to 10 percent. Conducted at Karolinska Institutet, the findings underscore the benefits of exercise at any age.
Researchers at Karolinska Institutet in Sweden have conducted a comprehensive 47-year study on how physical performance changes throughout adulthood. Known as the Swedish Physical Activity and Fitness study (SPAF), it followed several hundred randomly selected men and women, initially aged 16 to 63, through repeated measurements of fitness, strength, and muscle endurance.
Unlike previous cross-sectional studies that compare different age groups at one time, this longitudinal approach tracked the same individuals over nearly five decades, providing a detailed view of personal changes. The results indicate that peak physical capacity is typically reached around age 35, after which declines in fitness and strength begin, accelerating gradually with age. This pattern holds true even for those who were active earlier in life.
Despite the inevitable decline, the study offers hope: participants who increased their physical activity during adulthood saw improvements in their physical capacity ranging from 5 to 10 percent. "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," said Maria Westerståhl, a lecturer in the Department of Laboratory Medicine and the lead author.
The research, published in the Journal of Cachexia, Sarcopenia and Muscle, emphasizes that exercise remains effective in mitigating losses, though it cannot fully prevent them. The team plans to investigate the biological reasons behind the peak at age 35 and the partial protective effects of activity. Next year, the now-aging participants, reaching 68 years old, will undergo further examinations to link these changes to lifestyle, health, and underlying processes.
This work provides valuable insights into healthy aging, suggesting that maintaining or adopting physical routines can meaningfully support long-term well-being.
