Does the fractionalization of daily physical activity (sporadic vs. bouts) impact cardiometabolic risk factors in children and youth?

Abstract

Objective: Children 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.

Methods: Participants 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).

Results: The 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.

Conclusions: The relations between sporadic MVPA and bouts of MVPA with cardiometabolic risk factors were remarkably similar in children and youth.

Figure 1. Association between sporadic and bouts of physical activity with high summary cardiometabolic risk factor scores

. Odds ratio for a high cardiometabolic risk score (CRS) according to minutes per day of sporadic (dashed lines) and bouts (solid lines) of moderate-to-vigorous physical activity. In panel A (left), bouts were defined using a 5 minute threshold. In panel B (right), bouts were defined using a 10 minute threshold. Odds ratios were plotted from 0 minutes per day (referent) to values that corresponded to the 98^th percentile of the sample. Odds ratios were adjusted for sex, age, ethnicity, socioeconomic status, diet, smoking, and total accelerometer wear time.