Rise and Fall of Physical Capacity in a General Population: A 47-Year Longitudinal Study.

<p><b>BACKGROUND</b></p><p>As we age, there is a progressive decline in skeletal muscle tissue and function that can become clinically significant in the sixth decade of life affecting independent living and health. Longitudinal observations in elite athletes show that peak physical performance is reached before the age of about 35 years despite continuous training, suggesting that the tissue processes underlying muscle dysfunction may begin decades before they become clinically relevant.

To answer the question of whether the pattern of performance decline in athletes also applies to the general population, a population-based longitudinal study is needed.</p><p><b>METHODS</b></p><p>In the Swedish population cohort (SPAF), 427 individuals (48% women) born in 1958 underwent repeated objective assessments of physical capacity from age 16 to 63 years. Linear mixed models were used to estimate age- and sex-specific changes in the original cohort during the study period.</p><p><b>RESULTS</b></p><p>The estimated maximal aerobic capacity and muscular endurance (bench press repetitions) peaked at ages 26-36 in both sexes and declined gradually, starting at 0.3%-0.6% per year and accelerating to 2.0%-2.5% per year (main effect of age p < 0.001 and sex p < 0.01), with no sex difference in decline rates.

Muscle power was measured using the Sargent jump test, with men having their peak at age 27, and women at age 19. Group variance in physical performance increased markedly with age, with relative aerobic capacity showing a 25-fold increase, jump height a nearly 5-fold increase, and muscular endurance a threefold increase in variance from adolescence to age 63.

The rate of decline was small initially (0.2%-0.5% per year) but increased with age (2.2% per year), in both sexes (main effect of age p < 0.001 and sex p < 0.001), with no difference between the sexes. The overall decline in physical capacity from peak to age 63 ranged from 30% to 48%.

Higher leisure-time physical activity at age 16 and becoming active in adulthood were associated with better performance across all outcomes (p = 0.00-0.02); having a university degree was positively associated with absolute aerobic capacity (p = 0.04) and muscular endurance (p = 0.02).</p><p><b>CONCLUSIONS</b></p><p>The Swedish population cohort SPAF shows the same pattern of changes in physical capacity in adulthood as previously demonstrated for elite athletes. This confirms the concept that a decline in physical capacity can be observed before the age of 40, which can later lead to clinically significant physical dysfunction, especially in individuals with a sedentary lifestyle.</p><p><b>TRIAL REGISTRATION</b></p><p>ClinicalTrials.gov identifier: NCT06496204.</p>