Weekly Frequency of Meeting the Physical Activity Guidelines and Cardiometabolic Health in Children and Adolescents

David A. White; Erik A. Willis; Lauren T. Ptomey; Anna M. Gorczyca; Joseph E. Donnelly

Disclosures

Med Sci Sports Exerc. 2022;54(1):106-112. 

In This Article

Abstract and Introduction

Abstract

The current physical activity (PA) guidelines for children and adolescents in the United States recommend ≥60 min of moderate- to vigorous-intensity PA (MVPA), 7 d·wk−1 for cardiometabolic health (CmH) benefits. Although the duration and intensity components of the PA guidelines have been rigorously studied, the frequency (7 d·wk−1) component has not been thoroughly researched.

Purpose: This study aimed to examine the association of the frequency component of the weekly PA guidelines on CmH in youth.

Methods: Cross-sectional accelerometer data from the 2003–2006 National Health and Nutrition Examination Survey included youth age 6–18 yr with ≥4 d, ≥10 h of wear time, and averaging ≥60 min·d−1 of MVPA (n = 656). Participants were categorized into quartiles based on the proportion of days where they met the guidelines (≥60 min of MVPA). CmH variables were categorized as weight status/body anthropometrics, blood pressure, cholesterol, and fasting serum laboratory results. Propensity score weighting was applied to quartiles, and general linear modeling was used to compare associations of quartiles with CmH variables.

Results: Results are displayed as percent of days meeting guidelines (DMG; 95% confidence interval): MVPA in minutes per week: Q1 (n = 156; DMG = 45.8% (43.4%–48.1%); MVPA 467.5, min·wk−1), Q2 (n = 165; DMG = 62.6% (61.6%–63.7%); MVPA, 474.4 min·wk−1), Q3 (n = 148; DMG = 75% (74.1%–75.8%); MVPA, 446.5 min·wk−1), Q4 (n = 187; DMG = 92.2% (87.7%–96.6%); MVPA, 453.2 min·wk−1). After adjusting for confounders and multiple comparisons, there were no clinically significant differences in weight status/body anthropometrics, blood pressure, cholesterol, or fasting serum laboratory results between DMG quartiles.

Conclusions: We found no association between the proportion of DMG and CmH in children and adolescents. Our study suggests that achieving an overall weekly average of 60 min·d−1 of MVPA seems to be sufficient for CmH regardless of the 7 d·wk−1 frequency requirement of the PA guideline.

Introduction

The 2018 Department of Health and Human Services (DHHS) physical activity (PA) guidelines for Americans recommend children and adolescents 6–17 yr old participate in moderate- to vigorous-intensity (MVPA) aerobic activities for ≥60 min·d−1 and muscle/bone strengthening activities at least 3 d·wk−1 to support cardiometabolic health (CmH) and reduce the risk of developing obesity.[1,2] This PA guideline and other similar PA guidelines are based on the frequency, intensity, time, and type (FITT) principle with specific recommendations for days per week, duration, intensity, and modality. Although evidence exists to support the benefits of the intensity, duration (time), and modality (type) components of the child/adolescent guideline for CmH and risk of obesity,[1,2] there is very little evidence supporting the frequency component of the guideline. The frequency component of the DHHS guideline is based on the "daily minimum method"[3] where children and adolescents are required to participate in MVPA all 7 d of the week for ≥60 min·d−1 to sufficiently meet the guideline. Other PA guidelines, including those of the United Kingdom's National Health Service[4] and the World Health Organization,[5,6] use a "weekly average method," where children and adolescents can participate in an average of 60 min·d−1 of MVPA throughout the week, allowing for some day-to-day flexibility.

In adults, the 2008 PA guidelines transitioned from MVPA 5 d·wk−1 for 30 min (daily minimum method) to 150–300 min·wk−1 (weekly sum method), which remains in the newest DHHS guideline.[1] Experts hypothesized that eliminating the minimum weekly frequency requirement would allow for greater flexibility, permitting adults to customize their weekly routines to meet the PA guidelines in a way that aligns with their schedule.[7–9] The 2008 adult guidelines were supported by evidence suggesting that accumulating PA in longer duration sessions, but fewer times per week (i.e., "weekend warriors") led to a similar reduction in cardiometabolic disease–related mortality than those who are regularly physically active (≥3 d·wk−1).[9–11]

Although recommending ≥60 min of MVPA on all 7 d·wk−1 may help to reinforce formation of daily PA routines/active lifestyles in children and adolescents, the daily frequency requirement may not be feasible for many families. Youth are engaging in more nonsport extracurricular activities, leading to increased levels of stress over homework and academic performance.[12] In addition, parental employment demands, especially shift workers with irregular hours, may not have the ability to encourage or support PA participation all 7 d·wk−1.[13] Thus, many families may focus PA participation to less-busy days of the week, where, in some cases, the weekly sum volume of MVPA may be the same or greater than peers engaging in 60 min of MVPA daily.

To our knowledge, there is no research exploring the weekly frequency component of the PA guidelines on CmH and obesity in children and adolescents. Unlike the population of adults in the weekend warrior studies, cardiometabolic disease–related mortality is extremely rare in youth. Because of the positive association between obesity and risk factors for cardiometabolic disease in childhood and mortality in adulthood, between-group differences in CmH variables and obesity were chosen as the primary outcome for this study.[14,15] The purpose of this study is to examine the association of the weekly frequency component of the PA guidelines on CmH in children and adolescents. Our hypothesis is rooted in the findings of the weekend warrior studies, where weekly frequency of meeting the guidelines will have no significant association with on CmH or weight status.

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