To study the cross-sectional and longitudinal (2-year follow-up) association between muscle fitness and cardiovascular disease (CVD) risk factors in youth; whether there are muscle fitness cut points associated with CVD risk (cross-sectional); and whether the health-related muscle fitness cut points identified at baseline are associated with CVD risk 2 years later.

In total, 237 children (110 girls) aged 6-10 years and 274 adolescents (131 girls) aged 12-16 years with complete data were included in the study (10.3% drop out). The handgrip strength and the standing long jump tests were used to assess muscle fitness. CVD risk score was computed with sum of 2 skinfolds, systolic blood pressure, insulin, glucose, triglycerides, and total cholesterol/high density lipoprotein cholesterol.

Muscle fitness at baseline was associated inversely with single CVD risk factors and CVD risk score at baseline and 2-year follow-up (all P < .05). Receiver operating characteristics curve analyses showed a significant discriminating accuracy of handgrip strength in identifying CVD risk in children and adolescents (boys: ≥ 0.367 and ≥0.473; girls: ≥ 0.306 and ≥0.423 kg/kg body mass, respectively, all P < .001). Similarly, the standing long jump cut points for children and adolescents were ≥104.5 and ≥140.5 in boys, and ≥81.5 and ≥120.5 cm in girls, respectively (all P < .05). These cut points were associated with CVD risk 2 years later (all P < .01).

Muscle fitness is associated with present and future cardiovascular health in youth, and is independent of cardiorespiratory fitness. It should be monitored to identify youth at risk who could benefit from intervention programs.