Introduction

Older people are being urged, quite correctly, to take more physical exercise. The benefits of increased activity are becoming more obvious, thanks to well-conducted studies in a number of conditions. Unfortunately, one is encouraged to "exercise more", without further guidance. Creating an exercise program, whether at the gym or at home, requires some knowledge of the benefits of different types of training. Of course, it's also important to check with your family physician before undertaking such a program.

In general, training can be divided into two main types: aerobic exercise training (AT), where the main targets are the heart and lungs, and strength training (ST), which chiefly involves the muscles, bones and joints. Some machines have been introduced which attempt to combine AT and ST - e.g. the Stairmaster - but it is best, at least to start with, to know which type of training you really need, and what to do to get it. To help answer the first question, we have summarized a recent comprehensive review of the different benefits of each type of training.¹

The studies done in the early 1980s mostly examined the potential benefits of AT. More recently, the need for musculoskeletal health has been recognized, leading to increased use of ST. It will be seen that there is some overlap, however, in the benefits offered by each type of training, depending on the individual's physical condition.

Cardiac Risk Factors

With age, there is a natural decline in cardiac and respiratory performance, demonstrated by a decrease in maximum oxygen consumption (VO2max) on full exertion. Prolonged and intense AT, for instance on a treadmill, produces a substantial improvement in cardiac performance in men and women aged 60 to 80 years. ST does not have such an effect.

In older patients with high blood pressure (hypertension), AT is quite effective; low- to moderate-intensity training appears to be as effective as high-intensity exercise. ST, however, does not reduce blood pressure in older hypertensives.

Enlargement of the heart (increased left ventricular mass) can be reduced by AT in older hypertensive patients, over and above the effect that simply lowering blood pressure has. There are no results reported on the effects of ST on ventricular thickening in older people.

AT can produce clear-cut improvements in cholesterol levels; ST is less effective in this respect. In older people, both AT and ST improve glucose tolerance, to an almost equal degree. Obesity responds to both AT and ST. In particular, either form of physical training reduces the internal (intra-abdominal) fat in older people, particularly when used together with a suitable diet.

There are numerous changes in old age that encourage obesity. One of these is a reduction in the resting metabolic rate (RMR), the speed with which the body burns up calories. Both AT and ST can increase RMR, but its not clear which is the most effective.

Musculoskeletal Health

The strength of bone, or bone mineral density (BMD), decreases rapidly in women after the menopause for about 5 years, and then continues to decline at a slower rate. If the BMD declines to a low level - a condition called osteoporosis - spontaneous fractures can occur, and there is a greater risk of fractures after falls. There are several sorts of drug treatment for osteoporosis, but non-drug prevention of the fall in BMD is obviously desirable for women as they get older. ST has a clear beneficial effect on the BMD, especially in post-menopausal women. While AT also has a favorable action, it's not as useful as ST in this respect. However, AT is clearly better than not exercising at all.

Falls are a feature of aging. Exercise training (AT or ST) is associated with a reduced frequency of falls, due to improvements in gait and balance. Obviously, ST can reverse the loss of muscle strength and mass that occurs with aging, while AT is ineffective in this respect.

Joint flexibility lessens with age, leading to difficulties in climbing stairs, getting out of a chair, and so on. One would think that ST would improve flexibility, but this has not been shown to be the case. Indeed, sometimes both AT and ST can lead to a decrease in overall flexibility. Prolonged stretching exercises should always be included in the training program if there is any need to improve flexibility.

Conclusions

In summary, the authors conclude that to improve cardiac and pulmonary fitness, cholesterol levels and blood pressure, elderly persons should use a well-planned AT program. Glucose tolerance and obesity will respond to either AT or ST. The threat of osteoporosis and its consequences in post-menopausal women and lessened muscle quality in older persons is best countered by ST, rather than AT. If joint stiffening is to be addressed by physical training, proper stretching exercises must be included in any exercise program.