Moderate-to-vigorous physical activity, longitudinal trajectories of body mass index and waist circumference, and onset of obesity and abdominal obesity in older adults at high cardiovascular risk

Background Current European guidelines recommend 150-300 minutes/week of moderate or 75-150 minutes/week of vigorous-intensity physical activity for all adults (which translates into approximately 80-200 metabolic equivalents of task-minutes per day, MET-min/d). However, they do not differentiate by age or sex, are not specific for particular risk factors, and are not based on wide ranges of chronological age. Purpose To examine the relationship between moderate-to-vigorous leisure-time physical activity (MVLTPA) and changes over time in body mass index (BMI) and waist circumference (WC), as well as the risk of developing clinically significant obesity and abdominal obesity, and to identify optimal levels of MVLTPA among adults aged 60-80 years at high cardiovascular risk. Methods In participants from the Prevención con Dieta Mediterránea study, we estimated trajectories of BMI (N = 5,880) and WC (N = 5,502) between ages 60 and 80 according to MVLTPA levels. Participants were grouped into four categories: (1) 0 MET-min/d (null activity), (2) <100 MET-min/d (insufficient activity), (3) 100-200 MET-min/d (adequate activity), and (4) >200 MET-min/d (above-adequate activity). Longitudinal changes were modeled using mixed-effects regression with multivariate smoothed cubic splines. We also evaluated associations of MVLTPA categories and per-25 MET-min/d increments with incidence of general obesity (BMI ≥30 kg/m2) and abdominal obesity (≥89 cm in women, ≥103 cm in men), stratified by sex, using multivariable Cox proportional hazards models. Results BMI values over time were lower with increasing MVLTPA (compared with null activity, insufficient MVLTPA: differences ranging from -0.42 to -0.50 kg/m2; adequate: -1.23 to -1.47 kg/m2; above-adequate: -1.67 to -2.12 kg/m2). WC values over time were also lower with increasing MVLTPA, with minimal differences between adequate and above-adequate activity groups (insufficient: -0.47 to -2.12 cm; adequate: -2.29 to -2.98 cm; above-adequate: -2.31 to -3.15 cm). The association with obesity risk was non-linear, plateauing at ~140 MET-min/d (HR at that dose: 0.65, 95% CI 0.56 to 0.77). For abdominal obesity risk, the association was linear: each 25 MET-min/d increase up to 500 MET-min/d was linked to a 5% lower risk (HR 0.95, 95% CI 0.93 to 0.97), and adequate and above-adequate MVLTPA were associated with 45% (HR 0.55, 95% CI 0.39 to 0.78) and 54% (HR 0.46, 95% CI 0.33 to 0.65) lower risk, respectively. Associations were stronger in women than in men. Conclusions Higher MVLTPA was linked to healthier BMI and WC trajectories, with obesity incidence plateauing at ~150 MET-min/d (which matches current European recommendations), abdominal obesity risk declining linearly up to 500 MET-min/d, and stronger associations in women.