Cardiorespiratory Fitness

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The increasing prevalence of morbid obesity and superobesity (body mass index [BMI] ≥40, ≥ 50 kg/m2, >respectively) has prompted the need for safe and effective medical and surgical treatments. Pre-surgical evaluations are routinely used to determine global risk for these patients, including an assessment of cardiovascular function. PURPOSE: To determine that peak oxygen consumption (VO2 peak) and ventilatory-derived (V-slope method) anaerobic threshold (V-AT), expressed as a percentage of VO peak, would be markedly reduced in this patient subset. METHODS: Exercise testing was performed in conjunction with the direct measurement of VO peak on 65 (26 men, 39 women; mean ± SD age=48 ± 9 years) morbidly obese and superobese patients (mean ± SD, BMI=59 ±10 kg/m2) referred for bariatric surgery. A progressive protocol employing a recumbent cross trainer was developed, using the arm-levers and leg-pedals simultaneously. RESULTS: Sixty-four patients (98%) completed the exercise test protocol to volitional fatigue without eliciting ischemic ST-segment depression, threatening ventricular arrhythmias, or abnormal blood pressure responses or symptoms. Most (40/65, 62%) demonstrated a discernible V-AT. Selected cardiorespiratory variables (mean ± SD) at peak exercise are shown below:TableCONCLUSION: The present findings, from the largest database reported to date, indicate that aerobic fitness levels in morbidly obese and superobese adults are inversely related to BMI, and possibly to other factors that impair peak cardiac performance (e.g. chronotropic impairment). The decreased VO peak, however, is not paralleled by a relative reduction in the V-AT, expressed as the percentage of the VO peak. These data have implications for risk stratification and outcomes assessment in this escalating patient population.