Energy cost of walking and functional aerobic capacity during moderate intensity exercise in adults with obstructive sleep apnea: a cross-sectional study

Monira Aldhahi,Vivek Jain,Jeffrey E Herrick,Shipra Puri

doi:10.1186/s41606-021-00061-7

Abstract

BackgroundAutonomic dysregulation associated with obstructive sleep apnea (OSA) may limit cardiopulmonary responses to exercise, which, in turn, may impair functional aerobic capacity (FAC) and walking economy. We aimed to characterize walking economy and FAC in OSA patients compared with healthy adults (non-OSA) and examine their relationship with OSA severity (apnea-hypopnea index [AHI]).MethodsA total of 26 adults (OSA, n = 13; non-OSA, n = 13) participated in this cross-sectional study. In this study, the participants with OSA were between the ages of 25 and 60 years, with a body mass index of 25 kg/m2 to 39 kg/m2, and who had undergone a recent third-party sleep study with an AHI of 5 or greater. Participants completed a maximal integrated cardiopulmonary exercise test, three separate exercise bouts of constant work rate (CWR) treadmill test at 85% of anaerobic threshold (AT), and a 10-min walk test (10MWT). Multiple linear regression analysis corrected for weight, age, and BMI were performed to examine the associations.ResultsThere were significant differences between OSA and non-OSA participants in VO2peak (29.7 ± 5.6 mL/kg/min vs. 37.5 ± 6.5 mL/kg/min, p = 0.03) and Net VO2 during CWR (12.7 ± 5 vs.19 ± 6 mL/kg/min, p = 0.02). The 10MWT speed and distance were significantly lower in the OSA group (all p < 0.001). The energy cost of walking during submaximal exercise and 10-min walk test was higher among patients with OSA (all p < 0.001). The AHI scores were associated with 10MWT distance (R2 = 0.85, p < 0.001), energy cost of walking (R2 = 87, p < 0.001), and VO2 at anaerobic threshold (R2 = 0.92, p < 0.001).ConclusionsThe findings of this study show that patients with OSA have reduced FAC and a higher energy cost of walking. AHI explained 87% of variance in the energy cost of walking during the 10MWT. The results suggest that individuals with more severe obstructive sleep apnea experience greater impairment in functional performance.

Highlights

Autonomic dysregulation associated with obstructive sleep apnea (OSA) may limit cardiopulmonary responses to exercise, which, in turn, may impair functional aerobic capacity (FAC) and walking economy
The findings of exercise intolerance in our study demonstrated that the high energy cost of walking and decreased speed and distance in OSA patients may contribute to excessive daytime somnolence
The main findings in this study are that patients with OSA exhibited an increased energy cost of walking and reduced functional aerobic capacity during walking compared to non-OSA adults

Summary

Introduction

Autonomic dysregulation associated with obstructive sleep apnea (OSA) may limit cardiopulmonary responses to exercise, which, in turn, may impair functional aerobic capacity (FAC) and walking economy. Walking is the most common form of human physical activity that requires metabolic energy. It is the outcome of integration of multiple physiological systems working together to sustain walking pace for the required metabolic demand. Sleep disorders have been shown to limit the physical capacity in adults (Puri et al 2017) and is commonly associated with significant impairment in daytime physical functioning, fatigue, and daytime sleepiness that may limit daily life activities (Aguillard et al 1998). Despite extensive and ongoing scientific attention, understanding of the walking energy cost and mechanical efficiency for a given submaximal speed of walking in individuals with OSA have scarcely been studied

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