Evaluation of cardiorespiratory fitness using three field tests in obese adolescents: validity, sensitivity and prediction of peak VO2.

OBJECTIVES: Evaluation 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. DESIGN: Longitudinal interventional study in obese adolescents admitted to a rehabilitation centre for a 9-month programme of obesity management. METHODS: A 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. RESULTS: Thirty 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 VO2 and field test results. We observed significant correlations between pre- and post-intervention values of peak VO2 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 VO2 based on results from the 3 field tests using prediction equations specific to a population of obese adolescents. CONCLUSIONS: These 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 VO2 in these patients.

Effects of an in-patient treatment program based on regular exercise and a balanced diet on high molecular weight adiponectin, resistin levels, and insulin resistance in adolescents with severe obesity.

Adiponectin, the most abundant hormone produced by adipose tissue, circulates in 3 isoforms, including high molecular weight (HMW) adiponectin. The latter has been suggested to be a better predictor of metabolic disturbances and insulin resistance associated with obesity. This study investigated changes in total and HMW adiponectin, resistin, and homeostasis model assessment (HOMA) during a 9-month in-patient treatment program based on physical exercise and a balanced diet in 32 severely obese adolescents. Total and HMW adiponectin, resistin, and HOMA were measured at baseline (month 0) and during the program (months 3, 6, 9). In addition, a control group of 15 teenagers served as a reference for the baseline assessments. At baseline, HMW adiponectin was more markedly decreased in obese adolescents than total adiponectin, and both were lower than in controls. Conversely, resistin and HOMA were higher in obese adolescents. During the program, there was a significant change in body composition and improved insulin sensitivity among obese teenagers. In addition, HMW adiponectin and the ratio of HMW-to-total adiponectin increased throughout the study, whereas total adiponectin only increased up until the sixth month. On the contrary, resistin did not show any significant change. In obese adolescents, a long-term combination of aerobic exercise and a balanced diet, inducing change in body composition and improved insulin sensitivity, markedly increased HMW adiponectin compared with total adiponectin, without any change in resistin concentrations. Our results thus suggest that the determination of HMW adiponectin could be more useful than measurement of total adiponectin in clinical settings.

Detection of interstitial lung disease in systemic sclerosis through partitioning of lung transfer for carbon monoxide.

BACKGROUND: Interstitial lung disease (ILD) is a leading cause of death in systemic sclerosis (SSc). Sensitivities and specificities of the current pulmonary function tests (PFTs) for the detection of ILD in SSc are poor. OBJECTIVE: To determine whether diffusion capacity of the lungs for carbon monoxide (DLCO) partitioned into membrane conductance for CO (DmCO) and alveolar capillary blood volume (Vcap) could provide more sensitive clues to ILD than current PFTs. METHODS: DmCO and Vcap were determined in 35 consecutive SSc patients in whom a cardiac and/or pulmonary vascular abnormality had been rejected according to the recommended screening algorithm. ILD was diagnosed with high-resolution computed tomography. RESULTS: Among 35 patients [6 men; median age (first-third quartile) 61.9 years (49.5-67.7)], 22 had no ILD and 13 did. Total lung capacity (TLC), vital capacity and DLCO [percentage of predicted value (%pred)] were lower in patients with ILD [86 (82-103) vs. 106 (98-112), p = 0.01, 96 (88-112) vs. 114 (104-121), p = 0.04, and 67 (59-81) vs. 80 (71-94), p = 0.02, respectively]. DmCO (%pred) and the ratio of DmCO to Vcap were much lower in patients with ILD [54 (48-72) vs. 83 (66-92), p < 0.001, and 0.22 (0.21-0.27) vs. 0.40 (0.35-0.53), p < 0.0001, respectively]. According to receiver operating characteristic analysis, the DmCO:Vcap ratio displayed higher sensitivity and specificity than TLC, vital capacity and DLCO in identifying ILD in our study group (p < 0.01). CONCLUSIONS: These results suggest that the partitioning of DLCO might be of interest for identifying ILD in SSc patients.