Altered ventilatory responses to exercise testing in young adult men with obstructive sleep apnea
Received 3 June 2008; accepted 14 January 2009. published online 17 February 2009.
Summary
Background
Obstructive sleep apnea (OSA) is a disorder characterized by repetitive obstructions of the upper airway. Individuals with OSA experience intermittent hypoxia, hypercapnia, and arousals during sleep, resulting in increased sympathetic activation. Chemoreflex activation, arising from the resultant oscillatory disturbances in blood gases from OSA, exerts control over ventilation, and may induce increases in sympathetic vasoconstriction, contributing to increased long-term risks for hypertension (HTN) and cardiovascular disease (CVD).
Methods
To evaluate whether OSA elicits exaggerated ventilatory responses to exercise in young men, 14 overweight men with OSA and 16 overweight men without OSA performed maximal ramping cycle ergometer exercise tests. Oxygen consumption (VO2), ventilation, (VE), ventilatory equivalents for oxygen (VE/VO2) and carbon dioxide (VE/VCO2), and VE/VCO2 slope were measured.
Results
The VO2 response to exercise did not differ between groups. The VE, VE/VCO2, VE/VO2 were higher (p< 0.05, 0.002, and p<0.02, respectively) in the OSA group across all workloads. The VE/VCO2 slope was greater in the OSA group (p<0.05). The VE/VCO2 slope and AHI were significantly correlated (r=0.56, p<0.03). Thus, young, overweight men with OSA exhibit increased ventilatory responses to exercise when compared to overweight controls. This may reflect alterations in chemoreflex sensitivity, and contribute to increased sympathetic drive and HTN risk.
aLaboratory for Health and Exercise Science, Department of Human Nutrition, Foods and Exercise, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
bSleep Disorders Network of Southwest Virginia, Christiansburg, VA, USA
cDepartment of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA
dHuman Performance Laboratory, Clinical Exercise Physiology Program, Ball State University, Muncie, IN, USA
eEdward Via Virginia College of Osteopathic Medicine, Blacksburg, VA, USA
Corresponding author. Department of Human Nutrition, Foods & Exercise, Virginia Polytechnic Institute and State University, 213 War Memorial Hall (0531), Blacksburg, VA 24061, USA. Tel.: +1 540 231 6565; fax: +1 540 231 8476.
ABSTRACT