Joint associations between objectively measured physical activity volume and intensity with body fatness: the Fenland study

BACKGROUND/OBJECTIVES: Physical activity energy expenditure (PAEE) reflects the total volume of all physical activity, which can be accumulated with different intensity profiles. While volume and intensity have often been studied separately, less is known about their joint association with health. This study examined the combined association of PAEE volume and intensity composition with body fatness in a population-based sample of middle-aged British adults. METHODS: Data from 6148 women and 5320 men in the Fenland study with objectively measured physical activity (individually calibrated combined heart rate and movement sensing) and DXA-derived body fat percentage (BF%) were analyzed. Linear and compositional isocaloric substitution analyses evaluated associations of PAEE and its intensity composition with body fatness. Sex-stratified models were adjusted for socio-economic and dietary covariates. RESULTS: PAEE was inversely associated with body fatness in women (beta = −0.16; 95% CI: −0.17, −0.15 %BF per kJ day⁻¹ kg⁻¹) and men (beta = −0.09; 95% CI: −0.10, −0.08 %BF per kJ day⁻¹ kg⁻¹). Intensity composition added information beyond PAEE: reallocating energy to vigorous physical activity (>6 METs) from other intensities was associated with lower body fatness, whereas light activity (1.5–3 METs) was positively associated with body fatness. However, light activity was the main contributor to overall PAEE, and the relative importance of intensity was marginal compared with volume; in women, the PAEE difference between tertiles 1 and 2 was associated with ~3 percentage-point lower BF%, while increasing vigorous activity to the maximum observed within the same group was associated with ~1 percentage-point lower BF%. CONCLUSIONS: In this large cohort with objective measures, PAEE was inversely associated with body fatness. Beyond PAEE, greater intensity was also associated with lower body fatness, but this contribution was small relative to PAEE. Findings support guidelines emphasizing that any movement is beneficial, rather than focusing on specific intensity or duration targets.

Tim Lindsay, Katrien Wijndaele, Kate Westgate, Paddy Dempsey, Tessa Strain, Emanuella De Lucia Rolfe, Nita G. Forouhi, Simon Griffin, Nick J. Wareham, Søren Brage