Adults who consistently met physical activity guidelines had a lower risk of all-cause mortality—up to 46% at the upper bound of recommended activity levels—compared with those who remained inactive, according to a recent study.
For this systematic review and meta-analysis, researchers examined the associations between long-term physical activity (PA) patterns and mortality outcomes. The study, led by Ruyi Yu of the School of Public Health at The University of Queensland in Brisbane, Queensland, Australia, included 85 prospective cohort studies that examined physical activity trajectories, time-varying exposures, and cumulative or average PA in relation to all-cause, cardiovascular disease (CVD), and cancer mortality.
Key Findings
Being consistently active was associated with a 29% lower risk of all-cause mortality, while consistent leisure-time PA was associated with a 39% reduction. Increasing PA over time was linked to a 22% lower risk of all-cause mortality and a 27% reduction for leisure-time PA. In contrast, decreasing PA patterns showed minimal benefits: reductions were near null.
Among studies that used time-varying and cumulative PA models, high PA levels were associated with a 30% to 40% reduction in all-cause mortality compared with inactivity. Dose-response analyses demonstrated that engaging in PA levels equivalent to 8.75 to 17.5 marginal metabolic equivalent hours per week (mMET.h/week), which aligns with World Health Organization guidelines, yielded a 40% to 46% reduction in all-cause mortality risk. Risk reductions plateaued beyond these thresholds: the steepest decline occurred below 8.75 mMET.h/week which highlighted that even modest physical activity can yield substantial mortality benefits.
Consistently active participants experienced approximately 40% lower CVD mortality risk. In contrast, associations with cancer mortality were weaker and less consistent. The researchers noted inconclusive evidence, particularly for decreasing and increasing physical activity patterns. Findings remained stable across multiple sensitivity analyses and were more robust in studies with greater PA categorization and shorter follow-up intervals. "This suggests a possibility that binary classifications of PA levels might dilute the ‘highest vs lowest’ associations, potentially leading to underestimation of the benefits. This finding partially supports the ‘bank saving’ hypothesis, which states that previously accumulated PA could bring some health benefits," the authors wrote.
Methods
Studies were eligible for the review if they were population-based prospective studies with nonclinical adult populations. PA was assessed at a minimum of two time points and risk estimates for mortality were reported. The researchers converted PA exposure data into mMET.h/week and conducted separate meta-analyses for each exposure model. Subgroup, sensitivity, and dose-response analyses were also performed to assess robustness and identify nonlinear associations.
Because the study was observational, causality cannot be established, although the associations between physical activity and reduced mortality risk were strong and robust to unmeasured confounding.
They concluded that the review "may provide valuable insights for future research and public interventions aiming at promoting sustained PA in adults."
No competing interests were declared.