This increases the chance of sprains. Strength and flexibility decrease the risk of straining a muscle or joint. Because of the extra effort your heart makes during pregnancy, it beats faster. Even moderate exercise can make your heart stronger. During exercise, keep your heart rate lower than 140 beats per minute.
Pregnancy can affect breathing.
Expect to feel out of breath sooner than you normally would. If you can talk while you exercise, you are probably exercising at the right level. If you get out of breath, cut back. Lung fitness is improved with aerobic exercise. While pregnant, you may feel warmer than usual.