Warm-Up One must prepare the body before taking part in vigorous physical activity. A warm-up may help prevent injuries and maximize performance. The warm-up increases the body's internal temperature and the heart rate. The chance of getting injured decreases when the heart, muscles, ligaments and tendons are properly prepared for exertion. A warm-up may include some running in place or slow jogging, light stretching and calisthenics. It should last five to seven minutes and should occur just before the cardiovascular or the muscular conditioning part of the workout. After a proper warm-up, you are ready for a more intense conditioning activity.