If you are thinking of starting an exercise program late in life, the safest exercises are cycling and swimming.
A study from Japan shows that people with heart pain on exercising feel chest pain when they run and not when they pedal because it takes far more energy to run than to pedal. Running also causes more wear-and-tear injuries than pedaling. When you run, your foot hits the ground with a force greater than twice your body weight. This is transmitted up to jar your muscles, joints, and bones. Place your hands on the quad muscles in the front of your upper leg while you run. When you feet hit the ground, your quads shake like jelly. Pedaling and swimming are safer because you pedal in a smooth rotary motion and swim with the buoyancy of the water dampening forces on your muscles.
If you have a hard time walking up stairs, or getting out of a chair without using your hands, your thighs are weak and you can strengthen them by pedaling stationary bicycle.
You become weak because you do not use your muscles, not because you age. You use your thigh muscles raise you up stairs, and you strengthen these muscles by pedaling, skating, and skiing, not by walking or running. If you wobble, stumble or walk with your feet wide apart, you probably have weak thigh muscles and can strengthen them on a stationary bike. Pedal every other day until your legs feel heavy or hurt or you feel tired. Then stop. You should be able to gradually work up to the point where you can ride for thirty minutes, three times a week. Then walking up stairs and raising yourself out of a chair should be as easy as pedaling a bike.
