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Keywords:

  • energy expenditure;
  • cardiac function;
  • effort test;
  • fat free mass;
  • cardiovascular stress

Abstract

Objective: To investigate the effects of surgically induced weight loss on exercise capacity in patients with morbid obesity (MO).

Research Methods and Procedures: A prospective 1-year follow-up study was carried out, with patients being their own controls. A symptom-limited cardiopulmonary exercise stress test was performed in 31 MO patients (BMI > 40 kg/m2) before and 1 year after undergoing bariatric surgery.

Results: At 1 year after surgery, weight was reduced from 146 ± 33 to 95 ± 19 kg (p < 0.001), and BMI went from 51 ± 4 to 33 ± 6 kg/m2 (p < 0.001). After weight loss, obese patients performed each workload with lower oxygen consumption, heart rate, systolic arterial pressure, and ventilatory volume (p < 0.001). This reduced energy expenditure allowed them to increase the duration of their effort test from 13.8 ± 3.8 to 21 ± 4.2 minutes (p < 0.001). Upon finishing the exercise, MO patients before surgery were able to reach only 83% of their age-predicted maximal heart rate, and their respiratory exchange ratio was 0.87 ± 0.06. After weight loss, those values were 90% and 1 ± 0.08, respectively (p < 0.01). When we compared the peak O2 pulse corrected by fat free mass before and after surgery, no significant differences between the groups were found.

Discussion: After surgically induced weight loss, MO patients markedly improved their exercise capacity. This is due to the fact that they were able to perform the external work with lower energy expenditure and also to increase cardiovascular stress, optimizing the use of cardiac reserve. There were no differences in cardiac function before and after surgery.