Differential Changes in Exercise Performance After Massive Weight Loss Induced by Bariatric Surgery

Background: Exercise performance and pulmonary function are often impaired in severely obese subjects. Bariatric surgery represents the most effective therapy for severe obesity, but data on changes in exercise performance after massive weight loss induced by bariatric surgery have rarely been assessed so far. Methods: Exercise performance was obtained by bicycle spiroergometry in 18 severely obese patients before and at least 1year after bariatric surgery. Additionally, pulmonary function was assessed by spirometry. Results: BMI was reduced from 46.3 ± 1.6 to 33.5 ± 1.4kg/m2 after surgery. Pulmonary function (forced expiratory volume within 1s; inspiratory vital capacity) improved after weight loss (both p ≤ 0.01). At peak exercise, heart rate (HR) peak, absolute oxygen uptake (VO2) peak, and load peak did not differ between both assessments (all p > 0.25). However, relative (related to actual body weight) VO2 peak and workload peak were higher after than before surgery (both p ≤ 0.005), while gross efficiency peak and ventilatory equivalent peak remained unchanged (both p > 0.30). At anaerobic threshold (AT), patients showed lower HR AT and absolute VO2 AT after than before surgery (both p < 0.05), while absolute workload AT did not differ (p = 0.58). In turn, relative VO2 AT did not change (p = 0.30), whereas relative workload AT was higher after surgery (p = 0.04). Also, ventilatory efficiency AT and gross efficiency AT tended to be improved (both p = 0.08). Before surgery, the patients performed 27.0% of VO2 peak above their AT, while this fraction increased to 35.3% (p = 0.006). Conclusions: Results indicated differential changes in exercise performance, with the relative but not the absolute peak performance being improved after massive weight loss. Interestingly, anaerobic exercise tolerance was markedly improved after surgery