Background: Studies that have evaluated cardiopulmonary responses to exercise within the first few months of bariatric surgery have utilized cycle ergometry. However, walking is the most commonly reported mode of both pre- and post-operative PA. The divergent cardiopulmonary responses and metabolic costs of weight-bearing (walking) and non-weight-bearing (cycling) exercises warrant examination of the effects of bariatric surgery on cardiopulmonary responses during walking.
Methods: Nine women completed a maximal cardiopulmonary exercise test on a treadmill 2 weeks before and 3 months after gastric bypass surgery (GBS). Heart rate (HR), oxygen uptake (VO2), oxygen pulse (O2-p), and time to fatigue were compared before and after surgery and between the GBS group and a comparison group of 12 normal-weight (NW) women who completed the same exercise testing protocol.
Results: Time to fatigue increased by ~140 s following GBS (p = 0.018). No other parameter improved during maximal exercise from pre- to post-surgery. Body weight- and fat-free mass-corrected VO2 and O2-p at peak exercise differed between the GBS and NW groups before surgery, while only weight-corrected values were different following surgery. These differences disappeared after controlling for body fat percentage.
Conclusion: We have demonstrated that weight loss alone was not sufficient to improve select cardiopulmonary fitness measures during treadmill walking in obese females 3 months after GBS. However, we did observe a significant overall improvement in exercise capacity as the GBS group was able to exercise longer, presumably due to significant reductions in body mass and a subsequent reduced metabolic cost of walking.
Keywords: Bariatric surgery; Cardiopulmonary fitness; Gastric bypass; Obesity; Walking.