Aerobic exercise must be performed at least 3 times a week at a sustained heart rate of 110 to 120 beats a minute and maintained for at least 15 continuous minutes. The rate of 110 to 120 beats a minute is an approximate target for people of different ages. She was healthy and her pregnancy was normal, but she hadn't exercised much in the past. I told her good choices for aerobic exercise during pregnancy include brisk walking, stationary bicycling, swimming and aerobic exercise designed especially for pregnant women. I helped Nancy design an exercise program that would work for her.
Some women exercise for muscle strength.
To strengthen a muscle, there has to be resistance against it. There are three different kinds of muscle contractions isotonic, isometric and isokinetic. Isotonic exercise involves shortening the muscle as tension is developed, like lifting a barbell. Isometric exercise occurs when the muscle develops tension but doesn't change its length, such as pushing against a stationary wall. Isokinetic exercise occurs when the muscle moves at a constant speed, as when you swim.