Altered ventilatory responses to exercise testing in young adult men with obstructive sleep apnea

Laboratory for Health and Exercise Science, Department of Human Nutrition, Foods and Exercise, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
Respiratory medicine (Impact Factor: 3.09). 02/2009; 103(7):1063-9. DOI: 10.1016/j.rmed.2009.01.010
Source: PubMed


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).
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 (VO(2)), ventilation, (V(E)), ventilatory equivalents for oxygen (V(E)/VO(2)) and carbon dioxide (V(E)/VCO(2)), and V(E)/VCO(2) slope were measured.
The VO(2) response to exercise did not differ between groups. The V(E), V(E)/VCO(2), V(E)/VO(2) were higher (p< 0.05, 0.002, and p<0.02, respectively) in the OSA group across all workloads. The V(E)/VCO(2) slope was greater in the OSA group (p<0.05). The V(E)/VCO(2) 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.

Download full-text


Available from: William G Herbert, Jan 14, 2014
47 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Application of photonics in beam forming and steering for phased-array antennas is addressed in this paper. The feasibility of photonics in space communications systems centers around the basic issues such as the need for photonics and derived benefits, overall performance, and complexity and cost of implementation. Several optical beam forming and steering payloads are assessed for their capability and technology feasibility. Also included are the results of demonstrated proof-of-concept (POC) schemes
    Telesystems Conference, 1993. 'Commercial Applications and Dual-Use Technology', Conference Proceedings., National; 07/1993
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the study was to assess the effect of breathing and physical exercise on pulmonary functions, apnea-hypopnea index (AHI), and quality of life in patients with obstructive sleep apnea syndrome (OSAS). Twenty patients with mild to moderate OSAS were included in the study either as exercise or control group. The control group did not receive any treatment, whereas the exercise group received exercise training. Exercise program consisting of breathing and aerobic exercises was applied for 1.5 h 3 days weekly for 12 weeks. Two groups were assessed through clinical and laboratory measurements after 12 weeks. In the evaluations, bicycle ergometer test was used for exercise capacity, pulmonary function test, maximal inspiratory-expiratory pressure for pulmonary functions, polysomnography for AHI, sleep parameters, Functional Outcomes of Sleep Questionnaire (FOSQ), Short Form-36 (SF-36) for quality of sleep and health-related quality of health, Epworth Sleepiness Scale for daytime sleepiness, and anthropometric measurements for anthropometric characteristics. In the control group, the outcomes prior to and following 12-weeks follow-up period were found to be similar. In the exercise group, no change was found in the anthropometric and respiratory measurements (P > 0.05), whereas significant improvements were found in exercise capacity, AHI, and FOSQ and SF-36 (P < 0.05). After the follow-up period, it was shown that improvement in the experimental group did not lead to a statistically significant difference between the two groups (P > 0.05). Exercise appears not to change anthropometric characteristics and respiratory functions while it improves AHI, health-related quality of life, quality of sleep, and exercise capacity in the patients with mild to moderate OSAS.
    Sleep And Breathing 11/2009; 15(1):49-56. DOI:10.1007/s11325-009-0311-1 · 2.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Obese subjects commonly suffer from exertional dyspnea and exercise intolerance. Preliminary evidence suggests that treatment with nocturnal continuous positive airway pressure (nCPAP) may improve dyspnea in obese patients with obstructive sleep apnea (OSA), but the effect on exercise tolerance is unknown. This study sought to investigate whether nCPAP improves exercise tolerance and exertional dyspnea in obese patients with OSA. Obese patients prescribed nCPAP for moderate/severe OSA and without cardiopulmonary disease were recruited. Patients completed a constant-load exercise test and Baseline and Transitional Dyspnea Index questionnaires (BDI/TDI) at baseline and after one and three months of nCPAP. Primary outcome was change in constant-load exercise time from baseline to one and three months. Secondary outcomes included changes in isotime dyspnea, isotime leg fatigue and BDI/TDI score at one and three months. Fifteen subjects (body mass index = 43 kg m(-2), apnea-hypopnea index = 49(.)hr(-1)) were studied. Constant-load exercise time increased by 2.0 min (40%, p = 0.02) at one month and 1.8 min (36%, p = 0.04) at three months. At one and three months, isotime dyspnea decreased by 1.4 (p = 0.17) and 2 units (p = 0.04), and leg fatigue decreased by 1.2 (p = 0.18) and 2 units (p = 0.02), respectively. BDI/TDI scores were 2.7 (p = 0.001) and 4.5 points (p < 0.001) at one and three months. Peak oxygen consumption and static pulmonary function were unchanged. Nocturnal CPAP improves exercise tolerance and dyspnea in obese patients with OSA. Effects on exercise time and chronic dyspnea were seen after one and three months of nCPAP, while exertional dyspnea was only improved at three months.
    Respiratory medicine 10/2011; 105(10):1565-71. DOI:10.1016/j.rmed.2011.06.007 · 3.09 Impact Factor
Show more