Improved cardiovascular fitness (CVF) and body fatness during childhood and adolescence has been associated with a healthier cardiovascular profile not only during these years but also later in life. "It is unclear how the amount and intensity of physical activity (PA) are associated with in children," write Jonatan R. Ruiz, MD, from Karolinska Institutet in Huddinge, Sweden, and colleagues. "High CVF during childhood and adolescence has been associated with a healthier cardiovascular profile not only during these years but also later in life."
In this study, 780 children aged 9 to 10 years from Sweden and Estonia underwent measurements of accelerometry, expressed as minutes per day of total PA, moderate PA, and vigorous PA. CVF as watts per kilogram was measured with a maximal ergometer bike test, and body fat was derived from the sum of 5 skin-fold-thickness measurements. Using multiple regression analysis, the investigators determined the degree to which variance in CVF and body fat was explained by PA, after controlling for age, sex, and study location.
Lower body fat was significantly associated with higher levels of vigorous PA, but not with moderate or total PA; children engaging in more than 40 minutes of vigorous PA per day had lower body fat than did those who engaged in 10 to 18 minutes of vigorous PA per day. Total PA, moderate PA, and vigorous PA were positively associated with CVF, but those children engaging in more than 40 minutes of vigorous PA per day had higher CVF than those who engaged in less than 18 minutes of vigorous PA per day.
"The results suggest that PA of vigorous intensity may have a greater effect on preventing obesity in children than does PA of lower intensity, whereas both total and at least moderate to vigorous PA may improve children’s CVF," the authors write.
"With regular reports of increasing childhood obesity prevalence worldwide, the results of this study are noteworthy," the authors conclude. "Although we controlled for several potential confounders, such as age, sex, and study location, other variables such as food intake and genetic aspects may also have an influence."
· Previous recommendations have called for at least 60 minutes of daily moderate to vigorous PA for healthy children.
· In the current study, only vigorous PA was associated with a significant negative effect on body fat in children, but both moderate and vigorous PA improved CVF.
Am J Clin Nutr. 2006;84:299-303.
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