Increased post‐operative cardiopulmonary fitness in gastric bypass patients is explained by weight loss

Roux‐en‐Y gastric bypass (RYGB) leads to a major weight loss in obese patients. However, given that most patients remain obese after the weight loss, regular exercise should be part of a healthier lifestyle. The primary aim of this study was to investigate the cardiopulmonary fitness in obese patients before and after RYGB. Thirty‐four patients had body composition and cardiopulmonary fitness (VO2max) assessed and completed questionnaires regarding physical activity and function twice before RYGB (time points A and B) and 4 and 18 months after surgery (time points C and D). Weight loss was 37 ± 2 kg during the study period. VO2max increased (A: 21 ± 1 vs D: 29 mL/min/kg, P < 0.001), but absolute VO2max decreased (A: 2713 ± 126 vs 2609 ± 187 mL/min, P = 0.02) and VO2max per kilogram fat free mass did not change. Self‐perceived limitations to perform exercise decreased and self‐perceived physical fitness increased after RYGB. Self‐reported low‐ and high‐intensity physical activity did not change. With weight loss, self‐rated fitness level increased and the limitations to perform exercise decreased in RYGB patients. Nevertheless, as shown by the lower absolute VO2max, RYGB patients do not adopt new exercise habits following surgery.