Lower levels of physical activity volume are beneficial, and it’s never too late to start: Results from the HUNT Study, Norway

Abstract

Aims: We aimed to explore (a) how different patterns of physical activity (PA) over time (36 years) were associated with all-cause and cause-specific mortality, (b) if the association was similar for males and females and for different body mass levels and (c) how change in PA was associated with mortality for subjects who started out as physically inactive. Methods: The study is based on the prospective population-based cohort Trøndelag Health Study (HUNT) from 1984 to 2020, across four study waves. Data were linked to the Norwegian Cause of Death Registry. There were 123,005 participants, divided into three groups: persistently active, persistently inactive and mixed, with two cut-offs for PA: 60 and 150 minutes per week. The results are reported as cumulative incidence and hazard ratios (HRs). Results: At 60 minutes of PA per week, 8% of participants were persistently inactive, 15% were persistently active and 77% had a mixed pattern. At 150 minutes, the corresponding numbers were 32%, 2% and 65%. Compared to the persistently inactive group, for the 60-minute cut-off, the mixed group had an all-cause mortality HR of 0.83 (95% confidence interval (CI) 0.70–0.98), and the persistently active group had an HR of 0.51 (95% CI 0.40–0.65). For the 150-minute cut-off, the corresponding HRs were 0.84 (95% CI 0.75–0.94) and 0.48 (95% CI 0.26–0.88). The patterns were similar for males and females and across body mass index levels. Initially inactive participants had lower mortality if they ended up physically active, regardless of their activity level at an intermediate time point. Conclusions: At least 60 minutes of PA per week was associated with a marked reduction in mortality when this was a lasting habit over three decades. Given that six times as many people reach this less ambitious goal, it is vital to encourage all levels of PA in public health promotion. Any increase in PA during the lifespan is beneficial.