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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    ABSTRACT: Background Objective methods need to replace subjective methods for accurate quantification of physical activity. To be used in clinical settings objective methods have to show high reliability, validity and feasibility. The commonly used activity monitors are unable to detect the variety of physical activities. Multisensor activity monitors have larger potential for a more accurate quantification of physical activity. Children who have undergone surgery for congenital heart defects have the possibility to a physical active lifestyle because of the progress in cardiac surgery and cardiology. Aims To evaluate the ability of the multisensor activity monitors ActiReg, SenseWear Armband and IDEEA to assess physical activity and energy expenditure (I-IV), and to assess physical activity, sports participation and aerobic fitness in children who have undergone surgery for congenital heart defects (V). Methods I) Patients with chronic obstructive pulmonary disease (COPD) wore the ActiReg during 7 days with doubly labelled water as criterion for energy expenditure; II-III) 11-13 years old children performed different physical activities while wearing the ActiReg, SenseWear Armband and IDEEA with indirect calorimetry as criterion for energy expenditure; IV) a new ActiReg algorithm calibrated in 11-13 years old children was tested in 14-15 years old children wearing the ActiReg but also the SenseWear Armband during 14 days using doubly labelled water as criterion for energy expenditure; V) children who have undergone surgery for congenital heart defects and healthy controls in the age-groups 9-11 and 14-16 years wore the ActiReg during 7 days, were interviewed about sports participation and performed a maximal exercise test with measured oxygen uptake for the assessment of aerobic fitness. Results I) The ActiReg showed a mean (sd) accuracy of 99 (10) % in assessing energy expenditure in COPD patients; II-III) the accuracy of the SenseWear Armband and IDEEA in assessing energy expenditure varied between the different activities but showed an overall value of 81 (11) %/85 (8) % for the SenseWear Armband and 96 (10) % for the IDEEA; the SenseWear Armband showed increased underestimation with increasing intensity; the ActiReg algorithm overestimated moderate physical activity and the ActiReg had a limitation in registering vigorous physical activity; IV) the accuracy of the ActiReg with the new algorithm and the SenseWear Armband was 99 (11) % and 96 (10) %, both with increased underestimation with increasing intensity; V) children who have undergone surgery for congenital heart defects showed similar physical activity as the healthy controls but a tendency to lower amount of sports participation; in the older children, especially in boys, the patients had lower aerobic fitness; still, their amount of sports participation was considered high and their aerobic fitness moderate. Conclusions The ActiReg, SenseWear Armband and IDEEA have to be improved to become accurate instruments in clinical settings. While children who have undergone surgery for congenital heart defects had a physical activity level comparable to healthy children, some of them may require support for their engagement in exercise and vigorous physical activity.
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