Types of Exercise

Exercise should include the three main types: endurance (aerobic), strengthening (resistive, formerly called anaerobic), and stretching or flexibility (range-of-motion) exercises. Balance exercises are also important.

Aerobic exercise requires that oxygen get from the air through the bloodstream to the muscles, where it is used to produce energy. Thus, the heart and lungs are forced to work harder than normal. Aerobic exercise strengthens the heart and lungs and supplies the body with larger amounts of oxygen-rich blood. Aerobics also burns many calories. To be aerobic, exercise must be continued for at least 20 minutes, according to many experts. Walking, running, biking, rowing, swimming, dancing, and skating are aerobic exercise. Aerobic exercise should be done 3 to 7 times a week.

Strengthening exercise involves contracting muscles against resistance for up to 6 seconds at a time. Holding a contraction longer can increase blood pressure too much. There are two types: isotonic and isometric. Isotonic exercise involves moving the muscle against some form of resistance, such as gravity, weights, or rubber bands. (Weights may consist of cans of food or milk jugs filled with sand.) Isometric exercise involves contracting a muscle without moving a joint. The muscle is contracted and released several times. For example, in Kegel exercises, the muscles around the vagina, urethra, and rectum—the muscles used to stop the flow of urine—are contracted and then relaxed several times.

The main purpose of strengthening exercise is to make muscles stronger. Strengthening muscles is particularly important for older people because as people age, the amount of muscle tissue (muscle mass) and muscle strength tend to decrease. This type of exercise also benefits the heart and lungs but not as much as aerobic exercise. Strengthening exercise does not burn as many calories as aerobic exercise. But by increasing muscle mass, strengthening exercise eventually leads to changes in the body that make the body burn more calories. Strengthening the legs helps with balance because balance requires strong leg muscles. Strengthening exercises should be done about 2 or 3 times a week. Exercises for the same muscles should not be done 2 days in a row.

Some activities combine aerobic and strengthening exercise. For example, riding a stationary bike is aerobic (increasing endurance) and strengthens the leg muscles.

Stretching lengthens muscles and tendons and thereby improves flexibility and helps prevent injury. A person should stretch only after warming up or exercising, when the muscles are warm and less likely to tear. At first, each stretch should be held for 5 seconds, which is increased to 20 to 30 seconds as the person becomes more flexible. Then the person relaxes and does the same stretch again, stretching further if possible. Stretching exercises should be done 5 to 7 days a week.

If a pool is available, aerobic, strengthening, and stretching exercises can often be done in water more easily than on land. Water provides resistance that improves endurance and strengthens muscles. Water takes some stress off joints. It also provides support so that people are less likely to lose their balance. Some pools are designed specifically for exercise or therapy. In these pools, the water is no deeper than midchest level. Some communities offer water aerobic classes. Walking laps in a pool can provide similar benefits.

Some exercises are designed specifically to help improve balance. An example is balancing on one foot. This exercise can be done anytime anywhere. Standing up and sitting down without using the hands also improves balance. Tai Chi may improve balance and flexibility. Tai Chi involves a series of gentle and controlled movements, which resemble a slow dance. The whole body is used, and joints are moved through their range of motion. Careful attention is paid to breathing and posture. Tai Chi also focuses on calming the mind.