Influence of acute physical activity on stress reactivity in obese and normal weight children : a randomized controlled trial

Physical activity (PA) may influence acute stress reactivity in children differently depending on their weight. This randomized controlled trial investigated the impact of acute PA and of BMI status (overweight/obese (OB/OW) and normal weight (NW) on stress reactivity.; 50 prepubertal children (24 OW/OB and 26 NW) were randomly assigned to the PA or sedentary arm (SED) for 30 min followed by a stress task. Salivary cortisol, blood pressure (BP), and heart rate (HR) were measured.; An interaction effect between the randomization arms and weight status on salivary cortisol was found after the stress task (p = 0.04). Cortisol increased in the SED, but not in the PA arm (p = 0.004 for differences in time course) of NW children. Time course did not differ between both arms in OW/OB children (p = 0.7). OW/OB SED children had a flat cortisol course, and levels were reduced compared to the NW SED or the OW/OB PA children (p ≤ 0.03). Systolic BP increased only in the SED arm (p = 0.01). HR was higher in the PA than in the SED arm during stress (p < 0.001) and showed different time courses (p = 0.006).; PA impacted on acute stress reactivity and influenced stress reactivity differently in NW and OW/OB children.