RESUMO
OBJECTIVE: To demonstrate the ability of a submaximal test to predict VO(2max) in overweight children. STUDY DESIGN: A total of 130 children, 11 to 14 years old, with body mass index >85 percentile for age and sex performed a submaximal walking test. VO(2max) was measured by using open circuit spirometry during a graded exercise test to volitional fatigue. An equation to predict VO(2max) was modeled by using the variables of sex, weight (kg), height (cm), heart rate (HR) after 4 minutes during the submaximal test (4minHR), HR difference (4minHR - resting HR), and submaximal treadmill speed (miles per hour [mph]) in 75% of the subjects. Validation was performed by using the remaining 25% of subjects. RESULTS: A total of 113 subjects achieved a maximal effort and was used in the statistical analysis. Development and validation groups were similar in all aspects. On validation, the mean square error was 241.06 with the predicted VO(2max) within 10% of the observed value in 67% of subjects. CONCLUSION: VO(2max) was accurately predicted in this cohort of overweight children by using a submaximal, treadmill-based testing protocol.
Assuntos
Teste de Esforço , Sobrepeso/fisiopatologia , Consumo de Oxigênio/fisiologia , Adolescente , Estatura , Índice de Massa Corporal , Peso Corporal , Criança , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Modelos Biológicos , Fatores Sexuais , EspirometriaRESUMO
OBJECTIVE: We studied the relationship between % body fat (%BF), cardiovascular fitness (CVF), and insulin resistance (IR) in overweight middle-school children. STUDY DESIGN: Middle school children (n = 106, body mass index [BMI] > 95th percentile for age) underwent evaluation of body composition, maximal volume of oxygen utilization (VO2) uptake/kg lean body mass (VO2max/kgLBM), and fasting glucose and insulin (FI) concentrations and derived homeostasis model assessment index (HOMA(IR)). RESULTS: Both %BF (r = .33, P < .001) and VO2max/kgLBM (r = -0.42, P < .0001) were significantly correlated with FI. Bivariate regression analysis revealed %BF (P = .008 vs FI, P = .035 vs HOMA(IR)) and VO2max/kgLBM (P < .001 vs FI, P = .009 vs HOMA(IR)) to be independent predictors of insulin sensitivity. In males, VO2max/kgLBM was a better predictor of FI and HOMA(IR) than %BF. CONCLUSIONS: In obese middle-school children, both %BF and VO2max/kgLBM are independent predictors of FI levels. The relationship between CVF and FI levels was significant in both sexes but was particularly profound and stronger than %BF in males. Efforts to reduce risk of type 2 diabetes mellitus in an increasingly obese child population should include exercise intervention sustained enough to improve CVF.