Writing more specific exercise prescriptions.

exercise, I used to be very general in my instructions: 20 to 30 minutes, at least 2 or 3 times a week, of whatever activity you like most (eg, walking, playing tennis, or swimming). My thought, to the extent I thought about it at all, was that if they liked the activity they engaged in, they would be more likely to persist in it. Similarly, if a patient told me that she swam 3 times a week, I was more than satisfied. It would not have occurred to me to say: swimming is great, but because it is not weightbearing, it is not good protection against osteoporosis. Although any form of exercise is better than a sedentary lifestyle, additional research in the field can guide prescriptions for exercise regimens as specific as our prescriptions for hyperten-sion medications or human immunodeficiency virus an-tiretroviral therapy. They should consider not only patient preference but also the differential benefits of different forms of exercise. Broadly speaking, exercises can be classified into 3 groups: aerobic exercise (eg, brisk walking, jogging, bi-cycling, swimming, and Tai chi), resistance training (eg, weights and resistance bands), and stretching exercises (eg, yoga). It is possible to combine different forms of exercise, such as jogging using arm weights. Also, there are existing systems of exercise that combine these different elements. For example, the Pilates method fo-cuses on increasing muscle flexibility and strength. Cal-isthenics (eg, jumping jacks, push-ups, and sit-ups) are aerobic exercises that use the body's weight as the source of resistance. As physicians, it is important to understand the different physiologic effects and benefits of different forms of exercise so that we can guide our patients to the best regimen for them. Aerobic exercise has the strongest benefits on cardiovascular health due to its ability to increase maximum oxygen consumption, increase stroke volume, and decrease resting heart rate. 1 Resistance exercise increases muscle mass and strength. Although resistance exercises do not burn as many calories as aero-bic exercises per time engaged in the activity, increased muscle mass will result in increased metabolic demand, which will, in turn, result in decreased body fat, assuming the person does not make a corresponding increase in caloric intake. Because resistance exercises build muscle strength, they may be especially good for decreasing falls and improving balance. Stretching exercises improve range of motion and function of joints, tendon flexibility, and muscle performance and seem to prevent …