Aerobic exercise is any physical activity that makes people breathe harder and increases their heart rate. Light intensity exercise is when a person is doing aerobic exercise but can still sing. Moderate intensity exercise is hard enough that a person can carry on a conversation, but not sing. Vigorous intensity exercise means only a few words can be spoken. Any equipment that assists a person in aerobic exercise is aerobic equipment. This includes aerobic steps for use in step aerobics, workout DVDs and even free weight equipment such as dumbbells and fitness bands. Lifting weights quickly and with minimal rest such as during circuit training is aerobic exercise and provides strength training benefits.
Aerobic exercise requires the body to use increased oxygen levels to provide enough energy to continue exercising. This makes the lungs stronger as well as the heart, which must beat faster to distribute oxygen-rich blood throughout the body.