The impact of reduced muscular fitness on cardiometabolic risk factors in children aged 9-11 years

Aim: To analyse the relationships between muscular fitness (MF), fat mass (FM), fat-free mass (FFM) and its combined ratio with cardiometabolic risk (CMR) and whether the relationship between MF and CMR is mediated by body composition in schoolchildren. Methods: A cross-sectional study was conducted on schoolchildren from Cuenca, Spain, between September and November 2017. FM and FFM were estimated using bioimpedance analysis. The CMR index was calculated from triglycerides-HDL-c ratio, arterial pressure and fasting insulin. The MF index was assessed using handgrip and standing long jump tests. Analysis of covariance models assessed CMR index differences across the MF index and the FM/FFM ratio categories. Mediation analysis examined whether the MF index and the CMR index association were mediated by FM, FFM or FM/FFM ratio. Results: The analyses involved 485 schoolchildren aged 9-11 years (55.4% girls). Children with a higher MF index had a lower CMR index (p < 0.05). This association did not persist after controlling for FM/FFM. FM, FFM and FM/FFM ratio mediated the relationship between the MF index and the CMR index. Conclusion: Better levels of MF are associated with better cardiometabolic profile, but a healthy body composition is determinant to improve future health.