Occupations involving physical labor tend to be associated with lower life expectancy. Researchers here show that this is the effect of those occupations correlating with lower socioeconomic status and accompanying lifestyle choices. The physical activity is, as one might expect, associated with a modestly higher life expectancy where one can control for other factors. It is well established in other literature that greater physical activity correlates with reduced mortality and a longer life expectancy. The human data on activity and mortality cannot go far beyond mere correlation, but animal data makes it very clear that physical activity causes improvements in long-term health and life expectancy.
In this prospective cohort study, we linked data from Norwegian population-based health examination surveys, covering all parts of Norway with data from the National Population and Housing Censuses and the Norwegian Cause of Death Registry. 437,378 participants (aged 18-65 years; 48.7% men) self-reported occupational physical activity (mutually exclusive groups: sedentary, walking, walking and lifting, and heavy labour) and were followed up from study entry (between February, 1974, and November, 2002) to death or end of follow-up on Dec 31, 2018, whichever came first. We estimated differences in survival time (death from all causes, cardiovascular disease, and cancer) between occupational physical activity categories using flexible parametric survival models adjusted for confounding factors.
During a median of 28 years from study entry to the end of follow-up, 74 ,203 (17.0%) of the participants died (all-cause mortality), of which 20,111 (27.1%) of the deaths were due to cardiovascular disease and 29,886 (40.3%) were due to cancer. Crude modelling indicated shorter mean survival times among men in physically active occupations than in those with sedentary occupations. However, this finding was reversed following adjustment for confounding factors (birth cohort, education, income, ethnicity, prevalent cardiovascular disease, smoking, leisure-time physical activity, body-mass index), with estimates suggesting that men in occupations characterised by walking, walking and lifting, and heavy labour had life expectancies equivalent to 0.4, 0.8, and 1.7 years longer, respectively, than men in the sedentary referent category. Results for mortality from cardiovascular disease and cancer showed a similar pattern. No clear differences in survival times were observed between occupational physical activity groups in women.
Our results suggest that moderate to high occupational physical activity contributes to longevity in men. However, occupational physical activity does not seem to affect longevity in women. These results might inform future physical activity guidelines for public health.