We have previously emphasized the merits of resistance (strength) exercises in these pages, along with those of aerobic (endurance) exercises. The latter are usually done to help lose.

We have previously emphasized the merits of resistance (strength) exercises in these pages, along with those of aerobic (endurance) exercises. The latter are usually done to help lose weight and improved cardiovascular fitness. New advice from a special committee of the American Heart Association suggests that resistance exercises can produce similar, if less pronounced, benefits. However, in addition, they improve muscle strength and staying power, and thereby help prevent falls and injury in the elderly.

Aerobic exercise increases the maximum amount of oxygen that can be taken in and delivered to the tissues, as well as improving the metabolism of carbohydrates and lowering blood cholesterol levels. Until recently, resistance training has largely been thought capable of improving the strength, stamina and size of muscles, and not much else. However, the committee reports that it also increases the basal metabolic rate (BMR), i.e. calories are burned more quickly.

Both types of training have similar effects on bone mineral density (helping to prevent osteoporosis) and the likelihood of developing diabetes.

When muscles contract against resistance, there is a tendency to increased blood pressure and heart rate, which varies with the strength of the contraction. Measurements have shown that resistance training reduces this effect, so that strength-related activities of daily living (e.g. carrying in the groceries or firewood) can be done with a lessened increase in the heart rate and blood pressure -- obviously a good thing.

Those who have done 12 weeks of resistance training can be shown to improve their efficiency in running by 10%, walking by 30% and cycling by 40% (efficiency here means the amount that can be done before exhaustion sets in).

An added benefit of resistance training has recently been shown by analysis of 17 separate studies. Blood pressures of people who completed a course of resistance training were lowered by 2% (upper figure) and 4% (lower figure). This may not appear to be much of a decrease, but it is significant, and clinically important in helping to avoid some of the complications of high blood pressure.

Of course, there are questions concerning the safety of resistance training in people with heart and blood vessel conditions. The council recommendations state categorically that there is no risk associated with resistance training in healthy persons and low-risk cardiac patients (i.e. those without evidence of a poor blood supply to the heart muscle at rest or on exercise, or those with irregular heart rhythms or poor functioning of the heart muscle). Indeed, resistance training is now used in rehabilitation after cardiac events such as a heart attack (myocardial infarction, or MI). It is usually first added after about 3 months of aerobic training. In large studies of such patients, when using training ranging from 30 to 60 minutes, 6 to 26 weeks long, at 25% to 80% of maximum resistance, there were no incidents of pain associated with effort, no ECG changes indicating a poor blood supply to the heart muscle, and no irregular heart rhythms. Unfortunately, there is no information like this available for women.

Not everyone with heart or blood vessel conditions can undertake resistance training. People with such disorders must consult their physician before undertaking any aerobic or resistance training.

In summary, the new recommendations allow the idea that easy-to-moderately intense resistance training can help elderly people, as well as cardiac patients with mild or even moderate disease, to improve their muscle strength and endurance, and to modify their coronary risk profile. Resistance exercising often provides the opportunity to socialize, and the reduction in heart rate/blood pressure increases on lifting a load is beneficial to older patients in their everyday life.

The safety of resistance exercise has been demonstrated in healthy persons and men with relatively low-risk heart or blood vessel disease. Women and older patients with less healthy cardiovascular systems should be able to proceed with such training provided they get their physician's approval, and their training is closely supervised by an expert. Under these circumstances, the benefits are likely to exceed any possible risk of cardiovascular injury.

Source

Resistance exercise in individuals with and without cardiovascular disease: an advisory from the Committee on Exercise, Rehabilitation, and Prevention, Council on Clinical Cardiology, American Heart Association.  Pollock, BA. Franklin, G. Balady,  et al., Circulation, 2000, vol. 101, pp. 828--832