Thais Risso

Exercise Capacity and Obstructive Sleep Apnea in Lean Subjects

BACKGROUND Conflicting data regarding exercise capacity and obstructive sleep apnea (OSA) have been published, which may be partially explained by the difficulty of controlling all of the confounding factors. The aim of this study is to evaluate the exercise, anthropometric, and blood parameters in lean, sedentary patients with OSA compared with controls. METHODS Fifty-four lean subjects (including 27 patients with OSA and 27 controls) were selected. The control group was matched for age and gender. All subjects underwent polysomnography, anthropometric measures, a cardiorespiratory exercise test, two-dimensional transthoracic echocardiography, and spirometry. RESULTS The mean age was 52.9 +/- 7.9 years in subjects with OSA and 52.8 +/- 8.1 years in controls (P = .95). The cervical circumference was greater in the lean OSA group when compared with the controls (33.7 +/- 3.5 cm vs 31.4 +/- 2.8 cm; P = .01). There were statistical differences in the apnea-hypopnea index, minimal oxygen saturation, and mean oxygen saturation in the lean patients with OSA. Glycemia was higher in the lean OSA group (115.1 +/- 50.1 mg/dL vs 94.2 +/- 9.8 mg/dL; P = .04). There were no differences between groups in the peak oxygen consumption (Vo(2)), anaerobic threshold (AT), respiratory exchange ratio (RER), BP, and heart rate. CONCLUSION High glycemia and cervical circumference enlargement are the main characteristics of lean patients with OSA. Exercise performance is similar between groups, considering the peak Vo(2), AT, and RER. These results suggest that OSA does not impair functional capacity in lean subjects and that obesity probably participates in the diminished cardiopulmonary capacity observed in patients with OSA.

Cardiorespiratory response to exercise in men and women with obstructive sleep apnea

BACKGROUND OSA severity has been associated with self-reported lack of exercise. Most of the research has been done with men recruited from sleep clinics. There is limited data on the exercise performance of women with OSA. Therefore, the aim of this study was to assess exercise performance in a prospective, consecutive sample of men and women with OSA to compare their cardio respiratory parameters, arterial blood pressure and heart rate responses during and after exercise. METHODS Sixty-two subjects (32 men) completed the protocol. Men had a higher peak VO2, percent predicted peak VO2, VCO2, heart rate, systolic BP, and oxygen pulse than women. RESULTS There were no differences between men and women for peak oxygen saturation, peak Borg scales for dyspnea and leg fatigue and diastolic BP. A significant negative correlation was found between severity of OSA as measured by AHI, and peak VO2 (r=-0.4) in women, but not in men. CONCLUSION Men with OSA have higher peak VO2 and higher peak exercise heart rate than women with OSA; they also have higher end-exercise systolic BP than women and higher SBP during recovery from exercise; although this difference is not significant when adjusted for peak systolic BP. In men with OSA, there is no correlation between peak VO2 and AHI, but there is a significant correlation between these variables in women. Heart rate and blood pressure behaved similarly during exercise in both groups.