Condition category
Circulatory System
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

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 don’t 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

Trial website

Contact information



Primary contact

Dr Douglas Bradley


Contact details

550 University Avenue
M5G 1X8

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Effects of exercise training on obstructive and central sleep apnea in coronary artery disease: a randomized controlled trial


Study hypothesis

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.

Ethics approval

University Health Network Research Ethics Board; 09/09/2014; ref. 14-7748

Study design

Single-centre randomized controlled parallel group trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


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.

Intervention type



Not Applicable

Drug names

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)

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Angina
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
M5G 1X8

Sponsor information


Canadian Institutes of Health Research (Canada)

Sponsor details

160 Elgin Street
9th Floor
K1A 0W9

Sponsor type




Funder type


Funder name

Canadian Institutes of Health Research (Canada) - operating grant (MOP-82731)

Alternative name(s)

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)

Publication list

Publication citations

Additional files

Editorial Notes