Muscular fitness and clustered cardiovascular disease risk in Australian youth

Low cardiorespiratory Wtness (CRF) is a risk factor for cardiovascular disease (CVD) but the association of muscular fitness phenotypes (strength, endurance and power) on CVD risk in youth has not been examined. We examined the cross-sectional association between muscular fitness phenotypes with individual and clustered CVD risk factors and determined if any potential associations are independent of CRF. Participants were 1,642 youth aged 9, 12, and 15 years from the Australian Schools Health and Fitness Survey that had muscular strength (dynamometer), power (standing long-jump), and endurance (push-ups) as well as CRF (1.6 km run-time) measured. Outcomes included established risk factors (body mass index, waist circumference, blood lipids and blood pressure) and a clustered CVD risk-score. Muscular strength, endurance, and power were inversely associated with clustered CVD risk (all P < 0.05). After adjustment for body mass index, the association remained for muscular endurance and power (all P ≤ 0.001), but not strength. Muscular power was inversely related to prevalence of clustered CVD risk (≥ 80th percentile) within low (P_trend < 0.001), moderate (P_trend < 0.001), and high (P_trend = 0.001) CRF categories. Among youth, low muscular fitness levels as well as low CRF should be avoided for primary CVD prevention.