Evaluation of cardiorespiratory fitness using three field tests in obese adolescents: Validity, sensitivity and prediction of peak V˙O2

ObjectivesEvaluation of cardiorespiratory fitness in obese adolescents is necessary to develop personalised retraining programmes. We aimed to measure cardiorespiratory fitness using 3 field tests, and to evaluate their validity and sensitivity compared to values obtained by laboratory tests.DesignLongitudinal interventional study in obese adolescents admitted to a rehabilitation centre for a 9-month programme of obesity management.MethodsA 12-min walk/run test, an adapted 20 m shuttle walk-run test (starting speed 4 km h−1, increments of 0.5 km h−1 min−1) and a 4-level submaximal cycle ergometer test were performed to estimate respectively distance covered in 12 min, maximum speed and maximal aerobic power.ResultsThirty adolescents aged 14.2 ± 1.6 years were included. After 9 months intervention, we observed a significant reduction in body mass index, and an increase in peak V˙O2 and field test results. We observed significant correlations between pre- and post-intervention values of peak V˙O2 and distance covered in 12 min (r = 0.70 pre; r = 0.82 post), maximum speed (r = 0.80 pre; r = 0.83 post) and maximal aerobic power (r = 0.71 pre; r = 0.84 post). Multiple linear regression made it possible to estimate peak V˙O2 based on results from the 3 field tests using prediction equations specific to a population of obese adolescents.ConclusionsThese field tests, including the adapted 20 m shuttle walk-run test, adequately assess cardiorespiratory fitness in obese adolescents, and are sensitive to changes over time. Predictive equations including BMI are useful in clinical practice to predict peak V˙O2 in these patients.