Cardiac exercise rehabilitation consists of walking and bicycling activities. As the population requiring rehabilitation is aging, other forms of exercise may be useful and better tolerated. Tai Chi has been used for centuries, is easy to perform even by more debilitated individuals, and promotes improvement in blood pressure, fitness, and relaxation. Tai Chi may be more beneficial for frail cardiac patients because it is especially suited for the unfit and elderly, and can be practiced anywhere. Further studies are required to assess this form of exercise in cardiac patients. The objective of this randomized controlled study is to compare the effects of Tai Chi to "sham exercise" training in 200 frail cardiac patients who have completed six months of cardiac rehabilitation and are 60 years of age or older. Participants will be randomized to Tai Chi or "sham exercise" training and have their gait speed, blood pressure, heart rate, exercise capacity, balance, quality of life and cognitive function assessed before and after 24 week of training.

The role of exercise training is well established for cardiac patients to improve fitness and clinical outcomes. Many older cardiac patients even if they initially participate do not maintain regular exercise for a number of reasons. As the population ages there is a need to evaluate other forms of exercise training that may be used alone or in conjunction with standard approaches. Tai Chi is a potentially beneficial exercise for older cardiac patients because it is low-intensity exercise especially suited for unfit and elderly patients. There has been little rigorous evaluation, especially in the cardiac populations, of Tai Chi.

The main objective of this study is to assess the effects of Tai Chi compared to "sham exercise" in cardiac patients that have completed a program of cardiac rehabilitation. The investigators hope to show that six months of Tai Chi training compared to "sham exercise" (with all participants instructed to maintain their standard exercise program), will improve gait speed, exercise capacity, health related quality of life, cognitive function and balance.

This is a single blind randomized controlled trial of 200 cardiac patients, great than or equal to 60 years of age, who have completed six months of cardiac rehabilitation at the Hamilton Health Science Cardiac Health and Rehabilitation Centre. Participants will be randomized to receive either the short and simple 8-forms Tai Chi routine or "sham exercise". The participants in the study will train for a period of six months.

Inclusion Criteria:

1. Walking Speed < or = 1.3 m/sec during the gait speed assessment.
2. Evidence of cardiovascular disease based on a diagnosis of previous myocardial infarction, angiographic findings of coronary artery disease, previous percutaneous coronary intervention, or previous coronary artery bypass graft surgery.
3. Local resident, with available transportation to the Cardiac Health and Rehabilitation Centre (CHRC) at the Hamilton Health Sciences General Division.
4. Ability to understand written and verbal instructions and provide written informed consent.
5. Stable cardiac medical therapy as demonstrated by no change in medication during the 3 months prior to randomization.
6. Previous completion of the 6 month Cardiac Rehabilitation program (including exercise training component) at the CHRC.

Exclusion Criteria:

1. New York Heart Association Functional class IV symptoms of shortness of breath or angina.
2. Development of angina or ST segment depression of > 1 mm during symptom limited exercise testing at < 80% of predicted maximum power output.
3. Development of dysrhythmias during exercise (> Lown grade 2).
4. Resting blood pressure greater than 160 mmHg systolic or 90 mmHg diastolic.
5. Abnormal blood pressure response to clinical exercise testing (decrease in systolic pressure below resting; decrease of > 20 mmHg in systolic pressure after the normal exercise increase; rise in diastolic blood pressure of > 15 mmHg; maximal systolic blood pressure in excess of 250 mmHg).
6. Maximum heart rate < 100 beats per minute in the absence of beta blocker therapy.
7. Respiratory limitation as assessed by pre-exercise pulmonary function testing (documented restrictive or obstructive lung disease; based on forced expired volume in 1 sec and/or vital capacity measurements < 70% of predicted).
8. Major orthopedic disability.