Effect of Weight Loss on Aerobic Capacity in Patients with Severe Obesity Before and After Bariatric Surgery

Severe obesity has been associated with adverse effects on physical capacity. In a prospective study, the aerobic capacity of severely obese patients was measured in order to observe the physiological response to weight loss from bariatric surgery. Sixty-five consecutive patients (40.4 ± 8.4 years old; 93.8% female; body mass index = 49.4 ± 5.4 kg/m²) were evaluated before bariatric surgery and then 6 and 12 months after surgery. Aerobic capacity was assessed with a scientific treadmill to measure maximal oxygen consumption (VO_2max), heart rate, blood pressure, time on the treadmill, and distance walked (modified Bruce test). For the three observational periods, VO_2max was 25.4 ± 9.3, 29.8 ± 8.1, and 36.7 ± 8.3 ml/kg/min; time on the treadmill was 5.4 ± 1.4, 6.4 ± 1.6, and 8.8 ± 1.0 min; and distance walked was 401.8 ± 139.1, 513.4 ± 159.9, and 690.5 ± 76.2 m. For these variables, significant results (p = 0.0000) were observed for the two postoperative periods in relation to the preoperative period. Severely obese individuals increased their aerobic capacity after successful bariatric surgery. The data also suggests that a positive and progressive relationship between weight loss and improvement in fitness as a moderate loss of weight 6 months after surgery already showed some benefit and an additional reduction in weight was associated with a better performance in the aerobic capacity tests at the 12-month follow-up.