Muscular and Cardiorespiratory Fitness are Independently Associated with Metabolic Risk in Adolescents. The HELENA Study

Abstract

PURPOSE: To examine the independent associations of muscular fitness and cardiorespiratory fitness with clustered metabolic risk in adolescents. METHODS: Data were gathered from the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescents) cross-sectional study. A total of 709 adolescents (346 boys) from 9 European countries, aged from 12.5 to 17.5 y, with complete muscular fitness, cardiorespiratory fitness and blood sample data, were included in this report. A muscular fitness index was computed as sum of age- and gender-specific z-scores of handgrip strength / body weight and standing broad jump. Cardiorespiratory fitness was estimated using the 20m shuttle run test. Risk factors included in the composite metabolic risk score (sum of age- and gender-specific z-scores) were waist circumference, systolic blood pressure, triglyceride, ratio total cholesterol / high-density lipoprotein cholesterol, and insulin resistance (HOMA). Sex, age, puberty and country were used as confounders. On the basis of body mass index (BMI), adolescents were classed as non-overweight or overweight (including obese). RESULTS: Muscular fitness index was negatively associated with clustered metabolic risk independent of cardiorespiratory fitness (b = -0.246, P < 0.001). Independent of muscular fitness, an inverse association was found between cardiorespiratory fitness and clustered metabolic risk (b = -0.283, P < 0.001). Moreover, the odds ratios for having a high clustered risk (above or equal 1 SD) in the least fit quartile compared with the most fit quartile were 5.9 (95% confidence interval (CI) = 3.2-11.0) and 4.9 (95% CI = 2.5-9.8) for muscular fitness and cardiorespiratory fitness, respectively. Significant differences in metabolic risk across muscular fitness levels persisted among non-overweight (P = 0.007) and overweight participants (P = 0.013). CONCLUSIONS: Our results show that muscular fitness and cardiorespiratory fitness are independently associated with metabolic risk in adolescence. Health promotion policies and physical activity programs for youths should be designed to improve both cardiorespiratory and muscular fitness. The HELENA Study was carried out with the financial support of the European Community Sixth RTD Framework Programme (Contract FOOD-CT-2005-007034).