Does OSA Distort Perception of Aerobic Exercise Capacity?

Abstract

Obstructive Sleep Apnea (OSA) is characterized by intermittent nocturnal airway occlusion, sleep fragmentation, and oxygen desaturation. OSA patients report a lower quality of life attributed to excess daytime sleepiness, fatigue, irritability, and impaired cognition. In addition, the great majority of OSA patients are obese and at increased risk for cardiovascular (CV) disease. It has been suggested that this symptom set reduces the perceptions of their ability to engage in and perform physical activities, including participation in aerobic exercise. Thus, encouragement of regular exercise as an adjunct to managing their obesity and excess CV health risks is not seen as viable. PURPOSE: To determine if OSA patients have a distorted perception of their aerobic exercise capacity. METHODS: Forty three sedentary individuals (Mean age ± SD = 36.1 ± 14.4 yr, BMI 31.5 ± 7.9 kg/m2 76% males) with diagnosed OSA [Apnea Hypopnea Index (AHI) = 18.3 ± 13.1 events/hr] were compared to a similar group of 34 controls (27.5 ± 9.4 yr, BMI 28.1 ± 6.1 kg/m2 86% males) without OSA (AHI = 3.2 ± 1.5 events/hr). All were assessed by full overnight laboratory or with at-home polysomnography screening (Medcare, Reykjavik, Iceland). Each completed the Medical Outcomes Study Short Form-36 (SF-36), Veterans Specific Activity Questionnaire (VSAQ), Epworth Sleepiness Scale (ESS), and maximal effort cycle ergometer exercise test using a Δ15W ramping protocol. EPDS, an “Exercise Perception Distortion Score,” [(VO2pk -VO2pk predicted from VSAQ)/VO2pk × 100] was devised to represent distortion in the capability to self-estimate aerobic capacity. RESULTS: OSA and Non-OSA groups did not differ in measured VO2pk or the EPDS. Self-rating of aerobic exercise capacity by age-adjusted VSAQ was highly correlated to VO2pk for the entire sample (n = 77: r = 0.96, p<0.01), and within both the OSA (r = 0.98, p<0.01) and Non-OSA (r = 0.96, p<0.01) groups. The OSA patients reported more sleepiness (ESS, p<0.01), lower physical functioning (PF subscale, p<0.01), and lower role physical scores (RP subscale, p<0.01) than the Non-OSA group. CONCLUSION: Untreated OSA patients perceive themselves as sleepier and less able to engage in low-intensity physical activity. Yet, judgment of their aerobic exercise capacity is accurate and similar to that reported by sedentary individuals without OSA. These results encourage further research to evaluate the efficacy of moderate-vigorous exercise as an adjunct to medical management of CV disease risks in OSA patients. Supported by a grant from ResMed Sleep Disordered Breathing Foundation, Poway, CA.