Relationships among cardiorespiratory fitness, muscular fitness, and cardiometabolic risk factors in Japanese adolescents: Niigata screening for and preventing the development of non-communicable disease study-Agano (NICE EVIDENCE Study-Agano) 2.

OBJECTIVE: To examine the independent and combined associations of cardiorespiratory fitness (CRF) and muscular fitness (MF) with cardiometabolic risk factors in Japanese adolescents. METHODS: A cross-sectional study including 993 Japanese adolescents (aged 13-14 years) was undertaken. Height, body mass, blood pressure, lipid profile (non-fasting), and HbA1c were measured. The physical fitness (PF) test included measurements of CRF (20 m multistage shuttle run test), upper limb strength (hand grip strength), lower limb strength (standing long jump), and muscular endurance (sit-ups). The clustered cardiometabolic risk (CCMR) was estimated by summing standardized Z-scores of body mass index (BMI), mean arterial pressure (MAP), non-high-density lipoprotein cholesterol (non-HDL-C), and HbA1c. RESULTS: Linear regression analysis showed that all PF factors except for muscular endurance were inversely correlated with CCMR (P < .001). Among metabolic risk components, HbA1c was unrelated to PF, while non-HDL-C was inversely associated with CRF (B = -2.40; P < .001), upper limb strength (B = -1.77; P < .05), and lower limb strength (B = -1.53; P < .05) after adjustment for lifestyle factors. Logistic regression showed that the probability of having high CCMR (≥1SD) was synergistically higher in those with the lowest tertiles of both CRF and upper limb strength (P for interaction = .001); however, a substantially lower likelihood of having high CCMR was observed among individuals with the lowest tertile of upper limb strength but moderate CRF. CONCLUSIONS: Lower CRF and MF were significantly and synergistically associated with an unhealthier metabolic risk profile.