• Don't forget to take particular care of your feet! According to the American Podiatric Medical Association, proper shoes are crucial to successful, injury-free aerobics. Shoes should provide sufficient cushioning and shock absorption to compensate for pressure on the foot many times greater than found in walking. They must also have good medial-lateral stability. Impact forces from aerobics can reach up to six times your own body weight, which is transmitted to each of the 26 bones in the foot. Because of the many side-to-side motions, shoes need an arch design that will compensate for these forces, and sufficiently thick upper leather or strap support to provide forefoot stability and prevent slippage of the foot and lateral shoe "breakup." Make sure shoes have a toe box that is high enough to prevent irritation of toes and nails. Major shoe companies today have designed special shoes for aerobics, which provide the necessary arch and side support; they also have soles that allow for the twisting and turning of an aerobics regimen.
• Spinning is an exciting aerobic exercise developed in the 1980s. Participants use a specially designed stationary bike, and the instructor leads the class on an imaginary ride accompanied by energizing music. During an average 45-minute class, you can burn 400 to 500 calories. Be sure to talk with the instructor before your first class to go over the type of clothing you might need (padded shorts), your target heart rate and your physical limitations.
• Swimming is an ideal exercise for pregnant women and those with physical limitations such as musculoskeletal problems and asthma. However, swimming does not raise the heart rate quite as much as other aerobic exercises because humans are equipped with a reflex that causes the heart to slow down when immersed in water. For swimming, use a heart rate target of 75 percent of the maximum minus 12 beats per minute. It is also not the very best activity for losing weight because the body tends to conserve body fat as insulation in cold environments. For those whose only option is swimming, however, it is certainly better than remaining inactive. If you have arthritis, try to find a facility with a warm water pool that conforms to Arthritis Foundation guidelines.

Flexibility Training

Don't skip flexibility exercises, because they are beneficial in helping prevent cramps, stiffness and injuries. They also ensure a wide range of motion, particularly important as women age. Some flexibility/stretching regimes are popular enough now that you should be able to find a class for either that fits your needs and schedule:

• T'ai chi, an ancient Chinese practice, is becoming popular for older adults. T'ai chi incorporates slow, graceful movements with relaxation and breathing techniques. It is said to improve strength, flexibility, balance, coordination and posture, and is recommended by the National Institute on Aging because it may reduce older adults' risk of falling. The Arthritis Foundation calls it the ideal exercise for arthritis sufferers. Traditionally performed on land, t'ai chi can also be done in chest-deep water for added resistance and support.