Abstract
ObjectiveChildren and youth accumulate their daily moderate-to-vigorous physical activity (MVPA) in bouts (i.e., ≥5 consecutive minutes) and in a sporadic manner (i.e., <5 consecutive minutes). The study objective was to determine, within children and youth, whether MVPA accumulated in bouts is more strongly associated with cardiometabolic risk factors than an equivalent volume of MVPA accumulated sporadically.MethodsParticipants consisted of 2754 children and youth aged 6–19 years from the 2003–2006 National Health and Nutrition Examination Survey, a representative cross-sectional study. Bouts and sporadic MVPA were measured objectively over 7 days using Actigraph accelerometers. Thresholds of 5 and 10 consecutive minutes were used to differentiate between bouts and sporadic MVPA. A high cardiometabolic risk factor score (CRS) was created based on measures of waist circumference, non-high-density lipoprotein cholesterol, C-reactive protein, and systolic blood pressure. Associations were examined using logistic regression and controlled for covariates (sex, age, ethnicity, socioeconomic status, dietary fat and sodium, smoking, and accelerometry wear time).ResultsThe odds of a high CRS decreased in a dose-response for both the sporadic and bout MVPA measures. Relative to quartile 1, the odds ratio (95% confidence interval) for a high CRS in quartile 4 was 0.25 (0.10–0.60) for sporadic MVPA, 0.17 (0.09–0.34) for ≥5 minute bouts of MVPA, and 0.19 (0.11–0.34) for ≥10 minute bouts of MVPA. The sporadic and bout MVPA measures had a similar ability to distinguish between participants with high and normal CRS. Relative to 0 minutes of MVPA, an equivalent number of minutes of sporadic MVPA and bouts of MVPA had an almost identical odds ratio for a high CRS. The findings were consistent for 5 and 10 minute bout thresholds.ConclusionsThe relations between sporadic MVPA and bouts of MVPA with cardiometabolic risk factors were remarkably similar in children and youth.
Highlights
The cardiovascular, metabolic, and overall health benefits that children and youth achieve by engaging in moderate-to-vigorous intensity physical activity (MVPA) are well appreciated [1]
The median amount of MVPA accrued in bouts was 15 minutes per day when based on the 5 minute threshold and 8 minutes per day when based on the 10 minute threshold
A comparison of the C-statistic values suggests that each of the total, sporadic, and bout MVPA measures had a similar ability to distinguish between participants with a high and normal cardiometabolic risk factor score (CRS)
Summary
The cardiovascular, metabolic, and overall health benefits that children and youth achieve by engaging in moderate-to-vigorous intensity physical activity (MVPA) are well appreciated [1]. Within the past 3 years, new evidence-based physical activity guidelines for school-aged children and youth have been released by the World Health Organization [2] and health authorities in the U.S [3] and Canada [4]. These guidelines provide public health targets for the appropriate type, amount, intensity, and patterns of physical activity needed to achieve good health. The 60 minute per day dose of MVPA that has been recommended for children and youth is different than the 150 minutes per week dose of MVPA that is the foundation of the adult physical activity guidelines [2,3,4]. This reflects a lack of studies that have investigated the relevance of bouts of physical activity in the pediatric age group [1]
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