Purpose: In adults and school-aged children, physical activity is inversely associated with adiposity and cardiovascular disease risk. However, in children ≤5 years, these relationships remain unclear. This study aimed to determine if objectively-assessed physical activity is associated with measures of adiposity and vascular function in 4 year-old children.
Method: A cross-sectional study of 467 children (mean age 4.0±0.4 years) participating in the Barwon Infant birth cohort study (n=1074 infants). Participants wore an accelerometer for seven days. Mean overall? duration and durations accumulated in bouts ≥1 minute of light-intensity (LPA), moderate- to vigorous (MVPA) and light-vigorous-intensity (LMVPA) (hours/day) were computed. Adiposity was assessed by BMI z-score, waist circumference z-score, triceps z-score, subscapular skin fold z-score, and %body fat. Pulse wave velocity (m/sec) and systolic/diastolic blood pressure percentile were calculated for age, sex and percentile height. Linear regression between physical activity and vascular parameters were adjusted for accelerometer wear time and maternal education. Analyses with pulse wave velocity were adjusted for age and sex, and analysis with LPA were adjusted for time in MVPA.
Results: Overall duration and duration of bouts ≥1 minute of MVPA were associated with less adiposity, whereas LPA accumulated in bouts was associated with higher adiposity. Overall duration and duration of bouts of LPA accumulated in ≥1 minute were associated with lower systolic blood pressure (95%CI:-6.6 to -0.4mmHg and 9.3 to -1.3mmHg, respectively) and lower PWV (95%CI:-0.2 to -0.01m/sec and -0.3 to -0.004m/sec, respectively). MVPA was not associated with vascular outcomes; and LMVPA was not associated with any outcomes.
Conclusions: Findings from this study highlight the potential importance of LPA to cardiovascular function and MVPA to adiposity during early life. LPA was associated with more adiposity but lower blood pressure and slower pulse wave velocity. Future research should consider LPA and MVPA in addition to total physical activity.