Dose-response relation between physical activity and blood pressure in youth.

School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, Canada.
Medicine &amp Science in Sports &amp Exercise (Impact Factor: 4.46). 07/2008; 40(6):1007-12. DOI: 10.1249/MSS.0b013e318169032d
Source: PubMed

ABSTRACT The dose-response relationship between physical activity (PA) and cardiovascular health in children and adolescents is unclear. Blood pressure (BP) is a practical and useful measure of cardiovascular health in youth.
This study aims to examine the dose-response relationship between objectively measured PA and BP in children and adolescents.
The sample included 1170 youth aged 8-17 yr from the 2003/04 U.S. National Health and Nutrition Examination Survey. PA was measured using Actigraph accelerometers (Ft. Walton Beach, FL, USA) over 7 d. Thresholds of 2000 and 3000 counts per minute were used to denote those minutes where the participants were engaged in total PA and moderate-to-vigorous intensity PA, respectively. BP was measured using standard procedures. Systolic and diastolic BP values were adjusted for age, height, and sex. Participants with adjusted BP values > or = 90th percentile were considered to have hypertension. Thirty-six fractional polynomial regression models were used to obtain the dose-response curve that best fit the relation between PA with systolic BP, diastolic BP, and hypertension.
Inverse dose-response relations were observed between total and moderate-to-vigorous PA with systolic and diastolic BP. The slopes of the curves were modest indicating a minimal influence of PA on mean BP values. The likelihood of having hypertension decreased in a curvilinear manner with increasing minutes of PA. At 30 and 60 min.d of moderate-to-vigorous PA, the odd ratios (95% confidence intervals) for hypertension were 0.50 (0.28-0.64) and 0.38 (0.17-0.52), respectively, in comparison to no PA.
A modest dose-response relation was observed between PA and mean systolic and diastolic BP values. PA did, however, have a strong gradient effect on BP when predicting hypertensive values. These results support the public health recommendation that children and youth accumulate at least 60 min of moderate-to-vigorous PA daily.

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