Exercise more or sit less? A randomized trial assessing the feasibility of two advice-based interventions in obese inactive adults

Abstract

Objectives: The risk of metabolic and cardiovascular disease may be reduced by a healthy pattern of daily physical activity. We investigated the feasibility and preliminary effectiveness of advice-based interventions aiming at either increasing moderate-to-vigorous intensity physical activity (MVPA) or reducing sedentary time (ST) in obese volunteers.

Design: Randomized non-blinded two-armed trial.

Method: Inactive, obese adults were randomly assigned to reduce sedentary behavior (SitLess) (n=30) or increase MVPA (ExMore) (n=29) for 4 weeks. Participants wore ActivPAL (AP) and ActiGraph (AG) devices for 7 consecutive days at baseline and during the final week of the intervention period. Cardiometabolic risk factors (waist circumference, BMI, percent body fat, blood pressure, VO₂max and blood markers) were measured at baseline and at follow-up. Trial was set in Midtjylland Denmark from 2012 to 2014.

Results: The interventions were completed by 77% (SitLess) and 69% (ExMore) of the participants. The SitLess group reduced sedentary time by 53min/day (95% CI 10; 96; P<0.05) while ExMore increased MVPA by 16min/day (95% CI 5; 27; P<0.05). SitLess and ExMore both improved VO₂max by 8% and 11%, respectively (P<0.05). None of the other measured cardiometabolic risk factors changed over the 4 weeks of intervention.

Conclusions: This trial showed that completion of 4-week, advice-based interventions led to reduced ST or increased MVPA in obese adults. Furthermore, both interventions led to small significant increases in VO₂max. Studies of longer duration are needed to determine if these behavioral changes can be maintained, and to quantify possible longterm effects of reduced ST or increased MVPA on cardiometabolic risk factors.

Keywords: Obesity; Oxygen uptake; Physical activity; Sitting time.