The Acute Effect Of High Intensity Interval Exercise And Moderate Continuous Exercise On Endothelial Function In Children.

Abstract

PURPOSE: Chronic exercise training improves conduit artery endothelial function. Acute changes in endothelial function following a single bout of exercise are intensity and duration dependant, and are hypothesised to determine the chronic endothelial response to exercise training. Whilst this acute response is relatively well characterised in adults, little is known about the acute endothelial response in children. METHODS: Nine, healthy 10–11 year old children (7 female, BMI 16+6 kg/m2) completed, on separate days: i) 8*30 seconds cycling at 95% estimated maximum heart rate (HRmax), with a 90 second active recovery (HIIT), ii) 20 minutes of continuous cycling performed at 65% HRmax (CONT). Endothelial function was measured via flow mediated dilation (FMD) before (PRE), immediately post (POST) and 1 hour following exercise (POST1). Data were analysed using mixed linear modelling with allometrically scaled baseline artery diameter, and are presented as mean (95% confidence intervals). RESULTS: In the HIT condition, FMD was 7.68% (5.10 to 10.41) at PRE, then declined at POST (5.23% (2.45 to 8.02)) and POST1 (4.92% (2.42 to 7.43)). In the CONT condition, PRE FMD was 9.31% (6.70 to 12.03), POST 11.07% (8.38 to 13.87), and POST1 8.68% (7.00 to 12.43). Whilst FMD significantly differed by the mode of the exercise (P<0.001), there was no significant main effect of time (P=0.29), or interaction between exercise mode and time (P=0.20). CONCLUSION: In agreement with findings in adults and adolescents, our novel data suggest that changes in endothelial function in response to an acute bout of exercise in healthy, pre-pubertal children may be dependent on the type and intensity of the exercise performed, with high intensity interval exercise appearing to have a greater impact on post exercise FMD. Further research is needed to fully define the relationship between acute exercise intensity and FMD in children, and to establish how acute vascular responses determine chronic vascular adaptation.