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Indexed/Abstracted in: Chemical Abstracts, CINAHL, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,111
Online ISSN 1827-1928
EXERCISE PHYSIOLOGY AND BIOMECHANICS
Roberts M. D. 1, Drinkard B. 2, Ranzenhofer L. M. 1, Salaita C. G. 3, Sebring N. G. 3, Brady S. M. 1, Pinchbeck C. 1, Hoehl J. 2, Yanoff L. B. 1, Savastano D. M. 1, Han J. C. 1, Yanovski J. A. 1
1 Unit on Growth and Obesity, Developmental Endocrinology Branch, National Institute of Child Health and Human Development, (NICHD). Bethesda, MD, USA;
2 Rehabilitation Medicine Department, Clinical Research Center, Hatfield Clinical Research Center, National Institutes of Health, DHHS, Bethesda, MD, USA;
3 Nutrition Department, Hatfield Clinical Research Center, National Institutes of Health, DHHS, Bethesda, MD, USA
AIM: Maximal oxygen uptake (V.O2max), the gold standard for measurement of cardiorespiratory fitness, is frequently difficult to assess in overweight individuals due to physical limitations. Reactance and resistance measures obtained from bioelectrical impedance analysis (BIA) have been suggested as easily obtainable predictors of cardiorespiratory fitness, but the accuracy with which ht2/Z can predict V.O2max has not previously been examined in overweight adolescents.
METHODS: The impedance index was used as a predictor of V.O2max in 87 overweight girls and 47 overweight boys ages 12 to 17 with mean BMI of 38.6±7.3 and 42.5±8.2 in girls and boys respectively. The Bland Altman procedure assessed agreement between predicted and actual V.O2max.
RESULTS: Predicted V.O2max was significantly correlated with measured V.O2max (r2=0.48, P<0.0001). Using the Bland Altman procedure, there was significant magnitude bias (r2=0.10; P<0.002). The limits of agreement for predicted relative to actual V.O2max were -589 to 574 mL O2/min.
CONCLUSIONS: The impedance index was highly correlated with V.O2max in overweight adolescents. However, using BIA data to predict maximal oxygen uptake over-predicted V.O2max at low levels of oxygen consumption and under-predicted V.O2max at high levels of oxygen consumption. This magnitude bias, along with the large limits of agreement of BIA-derived predicted V.O2max, limit its usefulness in the clinical setting for overweight adolescents.