The Reallocation of Sedentary Time Is Associated with Longitudinal Improvements in Cardiometabolic Outcomes during Childhood.

OBJECTIVE

To use isotemporal substitution modeling to test how reallocating sedentary time to other movement behaviors is associated with longitudinal changes in cardiometabolic outcomes in children.

STUDY

DESIGN

Fifty-four children from the BrainChild Longitudinal Study completed 2 study visits 2 years apart, in which fasting blood draws were collected, and children wore wrist-accelerometers for 7-days. Isotemporal substitution modeling was used to evaluate the impact of reallocating 30 minutes of sedentary time with other movement behaviors (light-activity, moderate-physical-activity, vigorous-physical-activity, and sleep) on changes in cardiometabolic outcomes (body mass index, body-fat percent, systolic blood pressure, diastolic blood pressure, fasting insulin, fasting c-peptide, and insulin resistance) over 2-years adjusted for child age, sex, and puberty.

RESULTS

The reallocation of sedentary time to sleep time was associated with larger decreases in insulin secretion 2 years later, β = -5.98 (95% CI: -10.13, -1.82, P < .01). The reallocation of sedentary time to vigorous-physical-activity was associated with larger decreases in body-fat percent 2 years later, β = -0.07 (95% CI: -0.11, -0.03, P = .01).

CONCLUSIONS

These results suggest that sleep may be particularly beneficial for reducing excessive insulin secretion while vigorous physical activity may be beneficial for reducing excessive gains in body fat during childhood. Future interventional studies are needed to confirm these study findings.