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.