Targeting body composition in an older population: do changes in movement behaviours matter? Longitudinal analyses 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 and to examine whether reallocating inactive time into different physical activity levels was associated with 12-month change to body composition in older adults.

Methods: Longitudinal assessment nested in the PREDIMED-Plus trial. A subsample (n = 1564) of men and women (age 55-75 years) with overweight/obesity and metabolic syndrome from both arms of the PREDIMED-Plus trial was included in the present analysis. Participants 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 min of total PA and moderate-to-vigorous physical activity (MVPA) was associated with significant reductions in body fat (β - 0.07% and - 0.08%) and visceral adipose tissue (VAT) (- 13.9 g, and - 15.6 g) at 12 months (all p values < 0.001). Reallocating 30 min 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 SB and TV-viewing SB were associated with improved body composition in participants with overweight or obesity, and metabolic syndrome. This was also observed when substituting 30 min of inactive time with total PA, LPA and MVPA, with the greatest benefits observed with MVPA.

Trial registration: International Standard Randomized Controlled Trial (ISRCTN), 89898870 . Retrospectively registered on 24 July 2014.

Keywords: Body composition; Isotemporal substitution; Physical activity; Sedentary behaviour; Visceral adipose tissue.

Fig. 1

Flow chart of the study sample. DXA dual-energy X-ray absorptiometry, PA physical activity, SB sedentary behaviour, VAT visceral adipose tissue

Fig. 2

Isotemporal substitution of inactive time (30 min/day) with time in bed and physical activity on standardized body composition (z-score): analyses in completers only. The values shown are β (95% CI). These represent the change in outcome variables (z-scores) when substituting 30 min/day of inactive time with time in bed and physical activity. Mixed-effects linear models with random intercepts at recruiting centre, family and patient level were used to assess the isotemporal substitution of inactive time with time in bed, LPA and MVPA, adjusting for age, sex, intervention arm, time, educational level, smoking, diabetes, height, repeatedly measured total energy intake and total wear time. LPA, light physical activity; MVPA, moderate-to-vigorous physical activity; VAT, visceral adipose tissue. *p value < 0.05