Physical Activity and Mortality Across Levels of Adiposity: A Prospective Cohort Study From the UK Biobank.

OBJECTIVE

To examine the combined and stratified associations of physical activity and adiposity measures, modelled as body mass index (BMI), abdominal adiposity (waist circumference), and body fat percentage (BF) with all-cause mortality.

PATIENTS AND METHODS

Using the UK Biobank cohort, we extracted quintiles of self-reported weekly physical activity. Categories of measured BMI, waist circumference, and BF were generated. Joint associations between physical activity-adiposity categories and mortality were examined using Cox proportional hazards models adjusted for demographic, behavioral, and clinical covariates. Physical activity-mortality associations were also examined within adiposity strata. Participants were followed from baseline (2006 to 2010) through January 31, 2018.

RESULTS

A total of 295,917 participants (median follow-up, 8.9 years, during which 6684 deaths occurred) were included. High physical activity was associated with lower risk of premature mortality in all strata of adiposity except for those with BMI ≥35 kg/m. Highest risk (HR, 1.54; 95% CI; 1.33 to 1.79) was observed in individuals with low physical activity and high BF as compared with the high physical activity-low BF referent. High physical activity attenuated the risk of high adiposity when using BF (HR, 1.24; 95% CI; 1.04 to 1.49), but the association was weaker with BMI (HR, 1.45; 95% CI; 1.21 to 1.73). Physical activity also attenuated the association between mortality and high waist circumference.

CONCLUSION

Low physical activity and adiposity were both associated with a higher risk of premature mortality, but high physical activity attenuated the increased risk with adiposity irrespective of adiposity metric, except in those with a BMI ≥35 kg/m.