Muscular and cardiorespiratory fitness are independently associated with metabolic risk in adolescents: the HELENA study

Objective: To examine the independent associations of muscular and cardiorespiratory fitness with clustered metabolic risk in adolescents. Methods: Participants were 709 adolescents (346 boys) from 10 European centers, aged 12.5-17.5 yr, evaluated as a part of the Healthy Lifestyle in Europe by Nutrition in Adolescents cross-sectional study (HELENA-CSS). A muscular fitness score was computed using handgrip strength and standing long jump. Cardiorespiratory fitness was measured using the 20-m shuttle run test. Age- and gender-specific z-scores of waist circumference, systolic blood pressure, triglycerides, ratio total cholesterol/high-density lipoprotein cholesterol, and insulin resistance (homeostasis model assessment) were summed to create a metabolic risk score. Results: Muscular fitness was negatively associated with clustered metabolic risk independent of cardiorespiratory fitness (beta = -0.249, p < 0.001). Independent of muscular fitness, an inverse association was also found between cardiorespiratory fitness and clustered metabolic risk (beta = 0.264, p < 0.001). The odds ratios for having a high clustered risk (above or equal 1 standard deviation) were 5.3 [95% confidence interval (CI) = 2.6-10.6] and 4.3 (95% CI = 2.0-9.3) in the least fit quartile compared with the most fit quartile for muscular and cardiorespiratory fitness, respectively. Significant differences in metabolic risk between muscular fitness levels persisted among non-overweight (p = 0.012) and overweight participants (p = 0.011). Conclusion: Muscular and cardiorespiratory fitness are independently associated with metabolic risk in adolescents. These results support current physical activity recommendations for youth, which include muscle strengthening activities in addition to aerobic exercise.