Quick Take: Physical activity trajectories and mortality

While numerous studies have previously examined associations between physical activity and mortality, cardiovascular disease and certain cancers, the majority of this evidence has been cross-sectional, single-timepoint data, or has relied on a single baseline physical activity assessment for correlation. Few studies have examined physical activity trajectories over time, and subsequent risks of mortality. Of these, few have accounted for concurrent changes in other lifestyle factors. The aim of this population-based cohort study of community-based adults in the United Kingdom (n=14,599) was to examine associations of baseline and long-term physical activity trajectories with all-cause, cardiovascular and cancer-related mortalities. Study subjects were recruited from community general practices between 1993 and 1997 as part of the European Prospective Investigation into Cancer and Nutrition-Norfolk (EPIC-Norfolk). They were assessed at baseline, and were followed up until 2004 at three follow-up time-points by way of postal questionnaires and clinic visits to assess habitual physical activity and covariate lifestyle and clinical risk factors. Of note, quasi-continuous and marginalized values of physical activity energy expenditure (PAEE) in units of kilojoules (kJ)/kg/day were derived from three levels of occupational activity (unemployed or sedentary occupation, standing occupation, and physical or heavy manual occupation). Levels of leisure time physical activity were also ascertained through questionnaires. All participants were followed up using data from the Office of National Statistics until 2016 for mortality endpoints, and death certificates were used to ascertain causes of death. Primary outcome measures were all-cause, cardiovascular and cancer-related mortality. Over 171,277 person-years of follow-up, 3,148 deaths were observed, including 950 cardiovascular disease-related and 1,091 cancer-related deaths. For each 1 kJ per kilogram per day per year increase (equivalent to a trajectory of inactivity to meeting minimum physical activity guidelines as per the World Health Organization over 5 years), lower risks of all-cause mortality (HR 0.76, 95% CI 0.71 to 0.82), cardiovascular disease-related (HR 0.71, 95% CI 0.62 to 0.82) and cancer-related mortality (HR 0.89, 95% CI 0.79 to 0.99) were observed. Compared to consistently inactive individuals, increasing physical activity trajectories were associated with lower risks of all-cause mortality. Meeting and maintaining minimum physical activity guidelines (150 minutes per week of moderate-intensity activity) was associated with potentially preventing 46% of physical inactivity-related deaths. This study’s findings therefore indicate that middle-aged and older community-dwelling adults benefit significantly in terms of lifetime longevity with increased physical activity in addition to other lifestyle changes, with adherence to minimum physical activity standards having the potential to prevent close to half of inactivity-related deaths. These results encourage an increased focus on meeting physical activity standards at a population and public health level, particularly during mid and late life.

Click to read the study in the BMJ (British Medical Journal)

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