Respiratory muscle endurance training in obese patients

Objective: Increased respiratory muscle work is associated with dyspnea and poor exercise tolerance in obese patients. We evaluated the effect of respiratory muscle endurance training (RMET) on respiratory muscle capacities, symptoms and exercise capacity in obese patients. Design: A total of 20 obese patients hospitalized for 26 +/- 6 days to follow a low-calorie diet and a physical activity program were included in this case-control study. Of them, 10 patients performed RMET (30-min isocapnic hyperpnea at 60-80% maximum voluntary ventilation, 3-4 times per week during the whole hospitalization period: RMET group), while the other 10 patients performed no respiratory training (control (CON) group). RMET and CON groups were matched for body mass index (BMI) (45 +/- 7 kg m(-2)) and age (42 +/- 12 years). Lung function, respiratory muscle strength and endurance, 6-min walking distance, dyspnea (Medical Research Council scale) and quality of life (short-form health survey 36 questionnaire) were assessed before and after intervention. Results: Similar BMI reduction was observed after hospitalization in the RMET and CON groups(-2 +/- 1 kg m(-2), P < 0.001). No significant change in lung function and respiratory muscle strength was observed except for vital capacity, which increased in the RMET group (+ 0.20 +/- 0.26, P = 0.039). Respiratory muscle endurance increased in the RMET group only (+ 52 +/- 27%, P < 0.001). Compared with the CON group, the RMET group had greater improvement in 6MWT (+ 54 +/- 35 versus + 1 +/- 7m, P = 0.007), dyspnea score (-2 +/- 1 versus -1 +/- 1 points, P = 0.047) and quality of life (total score: + 251 +/- 132 versus + 84 +/- 152 points, P = 0.018) after hospitalization. A significant correlation between the increase in respiratory muscle endurance and improvement in 6MWT distance was observed (r(2) = 0.36, P = 0.005). Conclusions: The present study indicates that RMET is feasible in obese patients and can induce significant improvement in dyspnea and exercise capacity. RMET may be a promising tool to improve functional capacity and adherence to physical activities in this population, but further studies are needed to confirm these results. International Journal of Obesity (2011) 35, 692-699; doi: 10.1038/ijo.2010.191; published online 31 August 2010