Different types of physical activity promote different levels of strength, endurance and flexibility. Total fitness cannot be achieved without developing all three areas. Endurance is improved through aerobic exercise. To be aerobic, the exercise must use the large muscles, such as those in the legs and buttocks, be continuous and last for at least 30 minutes. During this time, the heart rate increases in an effort to provide a sufficient supply of nutrients and oxygen to the active muscle group.
Aerobic exercise builds muscle strength and endurance, as well as a healthy heart.
Examples of aerobic exercises include walking, jogging, swimming laps, and bicycling. Flexibility is increased through stretching exercises. Stretching exercises should be done before and after participation in sports or other activities, and as a regular part of fitness training. Never stretch in a way that causes any pain. If pain does happen while stretching, slowly stop doing that stretch and rest the painful muscle.