Physical Activity versus Fitness for Longevity

Regular physical activity is associated with many health benefits, including a lower risk of developing cardiovascular risk factors, chronic diseases, and premature mortality. In addition, higher physical fitness is strongly associated with lower all-cause and cardiovascular mortality. Physical fitness is partly inherited and is affected by habitual physical activity and exercise. For example, a meta-analysis (1) showed that genes could explain 44% of the VO₂max differences after aerobic training. The observational study of Menotti et al. (2) published in the European Journal of Preventive Cardiology explored the association between physical activity based on occupation and physical fitness, and their independent and joint effects in predicting all-cause mortality and the age of death. The study included seven European cohorts of four different countries of middle-aged men (n=5482), who were followed for over 60 years in which nearly all participants reached the endpoint. Physical activity was based on occupation and divided into low, intermediate, and high, whereas leisure time physical activity was excluded as those levels were very low. Physical fitness was derived from arm circumference (mm), heart rate (beats/min) and vital capacity (L/m²) and were combined into an overall score, which is different from commonly used methods to estimate (cardiorespiratory) fitness.

The study findings showed that more physical activity at work reduced the risk of death with similar effect estimates for the intermediate (13%) and high (15%) versus the lowest physical activity category. In addition, higher fitness levels reduced the risk of death, in which higher fitness resulted in an additional risk reduction (intermediate: 23% and high: 30%). The positive health benefits of physical activity and fitness were independent of each other, but the benefits were larger for fitness compared to physical activity. When looking at the age of death, individuals with higher levels of occupational physical activity lived 1.89 (intermediate) and 2.25 years (high) longer compared to low physical activity. For fitness, the study showed +2.84 and +3.79 years for intermediate and high, respectively, compared to low fitness. 

An interesting result is that the beneficial effect of physical activity was only present during the first 30 years of follow-up and disappeared after 30 years. The beneficial effect of fitness was present during the whole 60 years of follow-up. Importantly, physical activity and fitness were measured only once at baseline, and previous literature (3) showed that physical activity levels are likely to change over time which could impact the risk of death. Interestingly, some previous studies (4) suggested detrimental effects of occupational physical activity on all-cause mortality, which contrasts with this study. The differential effect might be due to differences in the type of occupation, type of physical activities performed at work, and other factors which were not considered (e.g. social economic status, sex, nutrition). Another potential explanation could be the presence of a cohort effect by birth year in men, which has been revealed in a Norwegian population study (5). They showed that very high occupational physical activity was associated with lower mortality risk in men born before 1940, while it was associated with higher risk in men born after 1950.

Nonetheless, this study showed the importance of physical activity and fitness in reducing premature deaths after 60 years of follow-up, in which fitness showed a stronger association with death compared to physical activity.