Optimal domain-specific physical activity and sedentary behaviors for blood lipids among Japanese children: a...

Optimizing childhood domain-specific physical activity (PA) and sedentary behavior (SB) for blood lipid profile is not well understood. We aimed to (1) determine the associations between accelerometer-measured PA and SB for each domain (school time and out-of-school time) with blood lipid profile and (2) estimate predicted changes in blood lipid profile with hypothetical time-reallocation between domain-specific SB and PA among Japanese children using compositional data analysis (CoDA).

This cross-sectional study included 284 children (147 boys and 137 girls) aged 9-12 years (mean age [years]: 10.1 ± 1.2 for boys, 10.0 ± 1.1 for girls; mean body mass index: 18.2 ± 3.2 for boys, 17.5 ± 2.5 for girls). Time spent in domain-specific SB, light-intensity PA (LPA), moderate-intensity PA (MPA), and vigorous-intensity PA (VPA) was assessed using accelerometry. The non-fasting lipid profile considered measures of triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and non-HDL-C levels. CoDA and isotemporal substitution model were performed to examine the associations of domain-specific PA and SB with blood lipids.

Time spent in out-of-school VPA relative to the other behaviors was negatively associated with non-HDL-C (boys: β_ilr1 = - 0.10, 95% confidence interval [CI] =  - 0.19 to - 0.01), TG (boys: β_ilr1 = - 0.45, 95% CI = - 0.68 to - 0.22), and positively associated with HDL-C (girls: β_ilr1 = 0.09, 95% CI = 0.02 to 0.16) after adjusting for age, body mass index, and time spent in SB, LPA, and MPA. During the out-of-school period, a replacement of 1 min of any other behavior with VPA was associated with decreases in LDL-C in boys (predicted changes [95% CI] - 0.03 mmol/L [- 0.05 to - 0.00] for LPA), non-HDL-C in boys (predicted changes [95% CI] - 0.03 mmol/L [- 0.06 to - 0.01] for SB and LPA) and TG in boys (predicted changes [95% CI] - 0.04 mmol/L [- 0.06 to - 0.02] for SB and LPA, - 0.05 mmol/L [- 0.07 to - 0.02] for MPA) and in girls (predicted changes [95% CI] - 0.02 mmol/L [- 0.04 to - 0.00] for LPA), and increases in HDL-C in girls (predicted changes [95% CI] 0.02 mmol/L [0.00 to 0.04] for SB and LPA, 0.03 mmol/L [0.00 to 0.05] for MPA).

Increasing out-of-school VPA might be an effective approach to improve blood lipid profiles among Japanese children.