Daily steps, cardiorespiratory fitness, and remnant cholesterol in schoolchildren: mediation effects for cardiovascular prevention

Background: To analyse the associations between daily steps, cardiorespiratory fitness (CRF), and remnant cholesterol in schoolchildren and to investigate whether the association between daily steps and remnant cholesterol is mediated by CRF.

Methods: This cross-sectional study involved 394 schoolchildren (aged 9-12 years, 53.0% girls) from Cuenca, Spain. Daily steps were measured using the Xiaomi MI Band 3, CRF was assessed using the 20-m shuttle run test, and remnant cholesterol was calculated from total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol. Mean differences in CRF and remnant cholesterol by daily steps and CRF categories were tested using analysis of covariance. Mediation analysis models examined whether CRF mediates the association between daily steps and remnant cholesterol.

Results: Children taking 12,000 and 9000 steps/day had higher CRF (p < 0.001) and lower remnant cholesterol (p = 0.034), respectively. Those with CRF > 47.59 kg/ml/min had lower remnant cholesterol (p = 0.009). CRF mediated the association between 1000 steps/day and remnant cholesterol (indirect effect = -0.027 (-0.055,-0.007)).

Conclusions: Both daily steps and CRF are associated with remnant cholesterol. Promoting an increase in daily steps may be a practical and promising strategy to increase CRF and, given its mediating role, to improve remnant cholesterol to prevent cardiometabolic risk in schoolchildren.

Impact: What's known: Remnant cholesterol is a critical indicator of cardiovascular disease risk in the early atherosclerosis. What's new: In schoolchildren, increased daily physical activity is significantly associated with higher cardiorespiratory fitness and lower remnant cholesterol, especially walking >9000 steps/day and >12,000 steps/day, respectively. What's relevant: Encouraging schoolchildren to take more daily steps may be a promising strategy to increase cardiorespiratory fitness and, given its mediating role, to improve remnant cholesterol to prevent cardiometabolic risk.