Effects of Interrupting Children's Sedentary Behaviors With Activity on Metabolic Function: A Randomized Trial

Abstract

Context: Limited data suggest that interrupting sedentary behaviors with activity improves metabolic parameters in adults.

Objective: We tested whether interrupting sitting with short, moderate-intensity walking bouts improved glucose tolerance in children.

Design: Participants underwent two experimental conditions in random order on different days: continuous sitting for 3 hours or sitting interrupted by walking (3 min of moderate-intensity walking every 30 min). Insulin, C-peptide, glucose, and free fatty acids were measured every 30 minutes for 3 hours during an oral glucose tolerance test. Area under the curve (AUC) was calculated from hormone and substrate measurements. Children were given a buffet meal after each condition.

Setting: The study was conducted at the National Institutes of Health Hatfield Clinical Research Center.

Participants: Twenty-eight normal-weight 7-11 year olds participated.

Main outcomes: Patterns of substrate/hormone secretion and AUC, as well as energy intake, were examined by experimental condition.

Results: Interrupting sitting resulted in a 32% lower insulin AUC (P < .001), 17% lower C-peptide AUC (P < .001), and 7% lower glucose AUC (P = .018) vs continuous sitting. Mixed model results indicated that insulin (P = .036) and free fatty acid concentrations (P = .009) were significantly lower in the interrupted vs the continuous sitting condition. Lunchtime buffet meal energy intake did not significantly differ between the conditions (975 ± 387 vs 963 ± 309 kcal; P = .85).

Conclusions: Interrupting sedentary time with brief moderate-intensity walking improved short-term metabolic function in non-overweight children without increasing subsequent energy intake. These findings suggest that interrupting sedentary behavior may be a promising prevention strategy for reducing cardiometabolic risk in children.

Trial registration: ClinicalTrials.gov NCT01888939.

Figures

Figure 1.

Participant flow through the study.

Figure 2.

The effect of sitting interrupted with 3 minutes of moderate-intensity walking every half hour (SIT+WALK) vs SIT on serum insulin concentrations (A); 3-hour insulin AUC (B); serum C-peptide concentrations (C); 3-hour C-peptide AUC (D); plasma glucose concentrations (E); and 3-hour glucose AUC (F). Unadjusted means ± SE are shown in A, C, and E. AUC results (B, D, and F) are mean ± SE adjusted for randomization order. *, Significantly different, SIT vs SIT+WALK; P < .05.