Changes in physical activity, sedentary behaviour and body composition: longitudinal analysis in the PREDIMED-Plus trial

Abstract

Background:The optimal distribution between physical activity (PA) levels and sedentary behaviour (SB) for the greatest benefits for body composition among older adults with overweight/obesity and chronic health conditions remains unclear. We aimed to determine the prospective association between changes in PA and in SB with concurrent changes in body composition. To examine whether reallocating inactive time into different physical activity levels was associated with 12-month change to body composition in older adults.Methods: A subsample (n=1564) of men and women (age: 55-75 years) with overweight/obesity and metabolic syndrome from the PREDIMED-Plus trial was included in the present analysis. Participant’s were followed-up at 6- and 12-months. Physical Activity and SB were assessed using validated questionnaires. Out of 1564 participants, 388 wore an accelerometer to objectively measure inactive time and PA over a 7-day period. At each time point, participants body composition was measured using dual-energy X-ray absorptiometry (DXA). Standard covariate-adjusted and isotemporal substitution modelling were applied to linear mixed-effects models.Results:Increasing 30 minute of total PA and MVPA were associated with significant reductions in body fat (β -0.07% and -0.08%) and VAT (-13.9g, and -15.6g) at 12-months (all p-values <0.001). Reallocating 30 minute of inactive time to MVPA was associated with reductions in body fat and VAT, and with an increase in muscle mass and muscle-to-fat mass ratio (all p-values <0.001).Conclusions:At 12 months, increasing total PA and MVPA and reducing total and TV-viewing SB were associated with improved body composition in participants with overweight or obesity, and metabolic syndrome. This was also observed when reallocating 30 minute of inactive time by total PA, LPA and MVPA, with the greatest benefits observed for MVPA.Trial registration: The trial was registered at the International Standard Randomized Controlled Trial (ISRCTN: http://www.isrctn.com/ISRCTN89898870) with number 89898870 and registration date of 24 July 2014, retrospectively registered.

Joint associations between objectively measured physical activity volume and intensity with body-fatness. The Fenland Study

“…Our results, at least in the time domain, are also consistent with previous observations in older British adults employing a similar exposure estimation technique, in which a positive association for sedentary time and inverse associations for both LPA and MVPA on body-fatness were reported, with a stronger magnitude of association for MVPA 21 . Comparable associations were also reported in a small sample of older high-risk Spanish adults with metabolic syndrome using wrist accelerometry-derived physical activity and DXA-derived body-fatness as estimated using linear isotemporal substitution analysis 26 .…”