Comparative relevance of physical fitness and adiposity on life expectancy: A UK Biobank observational study

Objective To investigate the extent to which two measures of physical fitness, walking pace and handgrip strength, are associated with life expectancy across different levels of adiposity, as the relative importance of physical fitness and adiposity on health outcomes is still debated. Patients and Methods Usual walking pace (self-defined as slow, steady/average, brisk), dynamometer assessed handgrip strength, body mass index (BMI), waist circumference and body fat percentage were determined at baseline in the UK Biobank prospective cohort study (March 13, 2006 – January 31, 2016). Life expectancy was estimated at 45 years old. Results The median age and BMI of the 474 919 participants included in this analysis were 58.2 years and 26.7 kg/m2, respectively; over a median follow-up of 6.97 years, 12823 deaths occurred. Participants reporting brisk walking pace had longer life expectancy across all levels of BMI, ranging from 86.7 to 87.8 years in women and from 85.2 to 86.8 years in men. Conversely, subjects reporting slow walking pace had a shorter life expectancy, being the lowest observed in slow walkers with a BMI less than 20 kg/m2 (women: 72.4 years; men: 64.8 years). Smaller, less consistent differences in life expectancy were observed between participants with high and low handgrip strength, particularly in women. The same pattern of results was observed for waist circumference or body fat percentage. Conclusion Brisk walkers were found to have a longer life expectancy which was constant across different levels and indices of adiposity. These findings could help clarify the relative importance of physical fitness and adiposity on mortality.