Is my Aerobic Workout Routine enough?

Cardiac Fitness Institute - London Health Science Centre - Ontario

Two major goals of cardiac rehabilitation are to improve physical functioning and reduce factors that contribute to progression of coronary artery disease. Aerobic exercise is intended to challenge the heart and lungs in order to increase their efficiency in providing oxygen to the working muscles. This is especially important in the cardiac patient because the blockage process that has taken place in their coronary arteries cuts down on blood flow and in turn oxygen supply to the heart muscle. Increased efficiency in supplying oxygen to the working muscles " saves " oxygen that is needed by the heart muscle.

However, with advancing age, adverse changes in body composition can have a "snowballing " effect on risk factors for cardiovascular disease and decrease functional capabilities. These changes include decreased lean body mass [muscle] and bone mineral density, as well as increased body fat mass. A decline in muscular strength has been associated with loss of lean body mass in older people and may contribute to decreased physical functioning and increased health problems. On the other hand, an increase in fat mass, with or without a decline in lean body mass, results in increased body fat percentage, which increases the potential for additional atherogenic risk factors such as diabetes, hyperlipidemia and hypertension.

Patients with coronary artery disease encounter activities during daily living which, require lifting or static carrying of moderately heavy objects, could benefit from increased muscular strength, known to result from resistance training. Resistance [strength] training results in patients being able to perform lifting and carrying tasks at a lower fraction of their maximum lifting capabilities. Generally, this improved strength also lowers heart rate and blood pressure response to muscular activity, acutely reducing circulatory and myocardial oxygen demands. Resistance exercise training's association with maintenance of lean body mass, bone mineral density and postural stability, reduces the risk of osteoporosis and helps to protect against injuries sustained from falling in the elderly. Thus, exercise routines that improve muscular strength and body composition may be important for the long-term well-being of cardiac patients.

A study by Person et al divided 36 patients into two groups: the first group did only aerobic exercise 3 times per week at 65 to 80% of their individual maximum heart rates. The second group did the same aerobic exercise routine, followed by 7 strength- training exercises, 3 times per week. After 6 months, the aerobic plus resistance training group achieved between 44 to 81% strength increase compared to only modest changes for the aerobic training only group - this corresponded to similar findings by Beniamini et al in a 12 week study of strength training in male cardiac patients. The aerobic plus resistance training group also had a 3% increase in lean body mass compared to a 1.1% increase and a decrease in body fat mass of 8.9% versus a 1.3% decrease in the other group - a study done by Campbell et al found similar results to these two changes in a 12 week resistance training program with older adults. Likewise, the group that did aerobic and resistance training showed a 12.1% decrease in resting heart rate compared to 3.9%, and an 8.4% decrease in heart rate at a constant load versus 4.2% in the aerobic only training group.

While resistance or weight training may not be appealing to you because it appears too difficult, or you are afraid of hurting yourself, you can see that the benefits far outweigh any risks. Your aerobic workout may be enough for you - it depends upon what your lifestyle requirements are. But, it appears from this research study that the optimal exercise routine for cardiac rehabilitation should include both aerobic and resistance training.

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