If your New Year's Resolution is to get in shape, pick an activity that you can enjoy and do safely for the rest of your life. Sixty-five percent of people who start an exercise program drop out in the first six weeks, often because of injuries.

Jogging and running are high-injury sports because your feet hit the ground with a force greater than twice your body weight. This force can injure muscles, joints and bones. Pedaling and swimming are safer because you pedal in a smooth rotary motion and when you swim, the buoyancy of the water dampens forces on your muscles.

The safest and most comfortable way to pedal is on a recumbent stationary bicycle. On a conventional bike, the pedals are below you, so you perch on a narrow seat and put pressure on the nerves in your crotch. When you pedal a recumbent bike, your legs are above your pelvis, so you can sit in a chair that does not pinch nerves. You lean against the seat’s back support, so it’s comfortable for anyone with back problems. Even a 90-year-old with poor coordination and weak muscles can use a recumbent bike. Put the bike in front of your TV, or listen to music, and your exercise time will pass quickly.

Don’t bother looking for an exercise machine or sport that stresses more than one group of muscles at the same time, such as a stationary bicycle that also moves your arms. Your brain will make you concentrate on the muscles that are doing the most work (in this case, your thighs that are moving the pedals), and the muscle groups that don’t need to exert force will just flip along for the ride. A better choice would be an ordinary stationary bicycle plus a separate weight training program to build muscles in your arms.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in four specialties, including sports medicine. Read or listen to hundreds of his fitness and health reports at http://www.DrMirkin.com

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