Effects of exercise training on sleep apnoea in patients with coronary artery disease: a randomised trial

Abstract

Overnight fluid shift from the legs to the neck and lungs may contribute to the pathogenesis of obstructive sleep apnoea (OSA) and central sleep apnoea (CSA). We hypothesised that exercise training will decrease the severity of OSA and CSA in patients with coronary artery disease (CAD) by decreasing daytime leg fluid accumulation and overnight rostral fluid shift.Patients with CAD and OSA or CSA (apnoea-hypopnoea index >15 events per h) were randomised to 4 weeks of aerobic exercise training or to a control group. Polysomnography, with measurement of leg, thoracic and neck fluid volumes and upper-airway cross-sectional area (UA-XSA) before and after sleep, was performed at baseline and follow-up.17 patients per group completed the study. Apnoea-hypopnoea index decreased significantly more in the exercise group than in the control group (31.1±12.9 to 20.5±9.4 versus 28.1±13.5 to 27.0±15.1 events per h, p=0.047), in association with a greater reduction in the overnight change in leg fluid volume (579±222 to 466±163 versus 453±164 to 434±141 mL, p=0.04) and by a significantly greater increase in the overnight change in UA-XSA in the exercise group (p=0.04).In patients with CAD and sleep apnoea, exercise training decreases sleep apnoea severity via attenuation of overnight fluid shift and an increase in UA-XSA.

Sleep Apnea

“…Another risk factor that has received recent attention is that of fluid around the upper airway (5,11). In individuals with lower-extremity edema, excess fluid may accumulate in the pharyngeal area with cephalad transposition of fluid from lower extremities to the neck area when supine (5,11), rendering the upper airway susceptible to collapse during sleep.…”

The role of physical exercise in obstructive sleep apnea

“…Mendelson et al 42 evaluated the effect of physical exercise on OSA and central sleep apnea in 34 individuals with coronary artery disease undergoing 4 weeks of aerobic exercise training, those 34 individuals being compared with a group of controls. All participants underwent polysomnography at baseline and follow-up, the following being measured before and after sleep: leg fluid volume; neck fluid volume; thoracic fluid volume; and upper-airway cross-sectional area.…”

Exercise: shifting fluid and sleep apnoea away

“…Additionally, it is unknown whether SDB severity improvement occurs only once aerobic exercise-induced training adaptations (e.g., increased VO 2peak ) manifest, which typically takes at least 8 weeks. Research in this issue of the European Respiratory Journal suggests that AHI reduction of 34% is achievable with as little as 4 weeks of exercise through attenuation of the nocturnal rostral fluid shift [20]. …”

“…Because the primary physiological mechanism preventing lower-limb fluid accumulation is leg skeletal muscle contraction, a highly inactive lifestyle may contribute to SDB severity through this mechanism [19]. Mendelson and colleagues hypothesized that exercise training would reduce the magnitude of nocturnal rostral fluid shift via engagement of muscle pump activity, thereby lessening the displacement of fluid to the thoracic cavity (for CSA) and neck (for OSA) and reducing AHI [20]. …”

“…In conclusion, Mendelson and colleagues provide intriguing experimental evidence that a short-term exercise protocol results in significant, albeit modest, reductions in SDB severity that occur alongside a reduction in nocturnal rostral fluid shift despite no change in body weight or fitness [20]. Further work is needed to explore whether similar reductions occur in women, adults without CAD, and among adults with CSA.…”