The relationship between work activity and risk of death. The Tromsø survey 1986-2021

Higher leisure time physical activity lowers mortality risk regardless of occupational physical activity level, but combining walking+lifting with an active leisure time also lowers mortality risk.

Background: Recent studies indicate that higher occupational physical activity associates with higher mortality risk, but results are inconsistent. It would be of public health relevance to further examine whether higher occupational physical activity contributes to longevity or whether such physical activity is harmful for the population, to implement appropriate public health measures. Our aims were to examine the association between 1) occupational physical activity and 2) combined occupational and leisure time physical activity, and risk of all-cause, cardiovascular disease (CVD) and cancer mortality using updating exposure and covariates over four decades.

Methods: We included working age adults (20-65 years) from Tromsø study survey 3-7 (1986-2016) in a prospective cohort design. Physical activity was self-reported in mutually exclusive ranks; occupational as sedentary, walking, walking+lifting, or heavy manual work; leisure time as inactive, active, vigorously active, or very vigorously active. Associations were examined using Cox/Fine and Grey regressions, adjusted for age (timescale), sex, body mass index, smoking, education, diet quality, alcohol intake, and leisure time physical activity.

Results: Of 29605 participants across 51959 observations, 2959 (9.9%) died, 752 (25.4%) of CVD and 1211 (40.1%) of cancer, during 29.1 median (interquartile range: 18.4) follow-up years. Compared with sedentary work, walking+lifting work was associated with lower all-cause (hazard ratio(HR): 0.87, 95% confidence interval (CI): 0.78-0.97) and CVD (subdistributed HR(SHR): 0.69, 95%CI: 0.55-0.87) but not cancer mortality (SHR: 0.96, 95%CI: 0.82-1.12). No risk differences were observed for heavy manual- or walking work. Compared with combined sedentary work and inactive leisure time, solely higher occupational physical activity was not associated with mortality but active leisure time combined with walking+lifting work (HR: 0.72, 95%CI: 0.62-0.84) displayed similar lower all-cause mortality risk as vigorously active leisure time combined with sedentary (HR:0.69, 95%CI: 0.59-0.81) or walking work (HR: 0.74, 95%CI: 0.62-0.88).

Conclusions: Higher occupational physical activity associates with lower risk of all-cause and CVD mortality, but not cancer mortality. Combining walking+lifting work with an active leisure time was associated with similar lower risks as solely being vigorously active in leisure.