BACKGROUND: Obstructive sleep apnea (OSA) predisposes individuals to cardiovascular morbidity, and cardiopulmonary exercise test (CPET) markers prognostic for cardiovascular disease have been found to be abnormal in adults with OSA. Due to the persistence of OSA and its cardiovascular consequences, whether the cardiovascular adaptations normally conferred by exercise are blunted in adults not utilizing established OSA treatment is unknown. The aims of this study were to document whether OSA participants have abnormal CPET responses and determine whether exercise modifies these CPET markers in individuals with OSA. METHODS: The CPET responses of 43 sedentary, overweight adults (body mass index (BMI) > 25) with untreated OSA (apnea-hypopnea index (AHI) >= 15) were compared against matched non-OSA controls (n = 9). OSA participants were then randomized to a 12-week exercise training (n = 27) or stretching control treatment (n = 16), followed by a post-intervention CPET. Measures of resting, exercise, and post-exercise recovery heart rate (HRR), blood pressure, and ventilation, as well as peak oxygen consumption (VO2peak), were obtained. RESULTS: OSA participants had blunted HRR compared to non-OSA controls at 1 (p = 0.03), 3 (p = 0.02), and 5-min post-exercise (p = 0.03). For OSA participants, exercise training improved VO2peak (p = 0.04) and HRR at 1 (p = 0.03), 3 (p < 0.01), and 5-min post-exercise (p < 0.001) compared to control. AHI change was associated with change in HRR at 5-min post-exercise (r = -.30, p < 0.05), but no other CPET markers. CONCLUSIONS: These results suggest that individuals with OSA have autonomic dysfunction, and that exercise training, by increasing HRR and VO2peak, may attenuate autonomic imbalance and improve functional capacity independent of OSA severity reduction.

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