Breaking Up Prolonged Sitting to Improve Cardiometabolic Risk: Dose-Response Analysis of a Randomized Cross-Over Trial

Abstract

Purpose 

Sedentary time is ubiquitous in developed nations and is associated with deleterious health outcomes. Physical activity guidelines recommend reductions in sedentary time, however quantitative guidelines that inform how often and how long sedentary time should be interrupted have not been provided. The purpose of this study was to examine the acute effects of multiple doses of a sedentary break intervention on cardiometabolic risk factors, concurrently evaluating efficacy of varying frequencies and durations of sedentary breaks.

Methods 

In a randomized cross-over study, middle- and older-aged adults (n = 11) completed the following 8-hour conditions on five separate days: 1 uninterrupted sedentary (control) condition and 4 acute (experimental) trials that entailed different sedentary break frequency/duration combinations: every 30 min for 1 min, every 30 min for 5 min, every 60 min for 1 min, and every 60 min for 5 min. Sedentary breaks entailed light-intensity walking. Glucose and blood pressure (BP) were measured every 15 and 60 min, respectively.

Results 

Compared to control, glucose incremental area under the curve was significantly attenuated only for the every 30 min for 5 min dose (-11.8[4.7]; p = 0.017). All sedentary break doses yielded significant net decreases in systolic BP from baseline compared to control (p < 0.05). The largest reductions in systolic BP were observed for the every 60 min for 1 min (-5.2[1.4] mmHg) and every 30 min for 5 min (-4.3[1.4] mmHg) doses.

Conclusions 

The present study provides important information concerning efficacious sedentary break doses. Higher frequency and longer duration breaks (every 30 min for 5 min) should be considered when targeting glycemic responses, while lower doses may be sufficient for BP lowering.