Plain English Summary
Background and study aims
Sleep apnea is a common sleep disorder in which breathing repeatedly stops and starts again as you sleep. There are 2 forms. Obstructive apnea (OSA) happens when the soft tissue at the back of your throat relaxes and blocks your airway. Central apnea (CSA) happens when your brain fails to stimulate your respiratory muscles to breathe. Sleep apnea prevents restful sleep and is linked with cardiovascular disease, including stroke and heart failure. The build-up of fluid in the legs during the day and then the shifting of this fluid into the neck and lungs due to gravity when in bed at night are related to OSA and CSA severity, respectively. Exercise training (ET) reduces the symptoms of sleep apnea, but we do not know why this is the case. The most likely cause, however, is the contraction of the calf muscle; this forces fluid out of the legs and reduces the amount of fluid shifting from the legs to the neck and lungs during sleep. ET in patients with coronary artery disease (CAD) reduces death rates, but again we dont know why. Sleep apnea increases the risk of death for CAD patients. Therefore, it is possible that ET could reduce the risk of death in CAD patients by reducing the severity of sleep apnea. Here, we want to see if ET does reduce OSA and CSA symptoms by reducing the amount of fluid build-up in the legs during the day and its movement into the neck and lungs at night.
Who can participate?
Adults aged between 18-80 with CAD.
What does the study involve?
Participants first undergo a sleep study to see whether they have OSA or CSA. Those that are found to suffer from sleep apnea are then randomly allocated into one of two groups. Those in group 1 do an exercise training programme for 5 days a week for 4 weeks. It includes some moderately intensive aerobic exercise and some light resistance training. Those in group 2 simply wait for a 4 week period. Physical activity levels of all the participants are measured at the start of the study using a actigraphy, an instrument worn on the wrist that measures movement of the body. All participants have the fluid content of their legs, neck and lungs measured and the severity of their sleep apnea assessed at both the beginning and end of the trial.
What are the possible benefits and risks of participating?
Participants that undergo the exercise training program may benefit from an improvement in the severity of their sleep apnea and overall improvement of their cardiovascular health.
Where is the study run from?
Toronto Rehabilitation Institute (Canada)
When is the study starting and how long is it expected to run for?
September 2014 to September 2015
Who is funding the study?
Canadian Institutes of Health Research (Canada)
Who is the main contact?
Dr Monique Mendelson
Effects of exercise training on obstructive and central sleep apnea in coronary artery disease: a randomized controlled trial
1. In coronary artery disease patients with obstructive sleep apnea, exercise training will reduce the apnea-hypopnea index in association with decreases in evening leg fluid volume, overnight changes in leg fluid volume and neck fluid volume and an increase in upper-airway cross-sectional area.
2. In coronary artery disease patients with central sleep apnea, exercise training will reduce the apnea-hypopnea index in association with decreases in evening leg fluid volume and overnight change in leg fluid volume and change in thoracic fluid volume, and an increase in PCO2 above the apnea threshold during sleep.
University Health Network Research Ethics Board; 09/09/2014; ref. 14-7748
Single-centre randomized controlled parallel group trial
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use the contact details below to request a patient information sheet
Coronary artery disease patients with obstructive or central sleep apnea
The intervention consists of an exercise training program including 20 sessions over a 4-week period. Each exercise session will begin with a 10 minute warm-up followed by 30 minutes of moderate-intensity aerobic exercise, as recommended by the American College of Sports Medicine and the Canadian Association of Cardiac Rehabilitation. Following aerobic exercise, on non-consecutive days, participants will perform approximately 20 minutes of supervised light resistance training. The intensity of aerobic exercise will be set at 60-80 % of peak oxygen uptake (VO2) or 70-80% heart rate reserve, as determined from the maximum exercise test.
The control group does not receive any intervention. They simply wait for a 4-week period.
Primary outcome measure
Apnea hypopnea index, measured by polysomnogram at baseline and 4-weeks
Secondary outcome measures
1. Leg fluid volume measured by bio-electrical impendence
2. Overnight changes in leg fluid volume, thoracic fluid volume, neck circumference and neck fluid volume measured by bio-electrical impendence
3. Upper-airway cross-sectional area measured by acoustic pharyngometry
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
Men and women 18-80 yrs of age with coronary artery disease (defined as a documented myocardial infarction, coronary bypass surgery or coronary angioplasty and/or stenting) and obstructive or central sleep apnea (AHI greater than 15 events/hr)
Target number of participants
Participant exclusion criteria
2. Use of diuretics
3. Adeno-tonsillar hypertrophy
4. Inability to walk due to orthopedic or musculoskeletal problems
5. Previously treated OSA
6. Patients exercising more than 150 minutes per week at moderate intensity
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
550 University Avenue
Canadian Institutes of Health Research (Canada) - operating grant (MOP-82731)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Basic results (scientific)