According to the U.S. Centers for Disease Control and Prevention, exercise is very important to children's health, and they recommend that children and teens should get at least an hour of exercise every day.The Physical Activity Guidelines for Americans, published by the Department of Health and Human Services, recommends that exercise be divided into aerobic activity, muscle strengthening exercise and bone strengthening exercise.
The CDC recommends that the bulk of a child's physical activity should consist of aerobic activity such as brisk walking, cycling or swimming. Strength training exercises, such as push-ups and sit-ups, are not likely to build muscle mass if the child has not reached puberty, but they are also important for overall fitness. High-impact activities, such as jumping rope and running, build strong bones as well.
At the age of 13, boys generally have begun to make the hormones necessary to begin to build muscle mass by working out with added resistance, according to Kids Health. However, powerlifting, competitive weightlifting and bodybuilding are not appropriate for young teens because bone, joint and ligament injuries are likely to occur. Girls can work out with weights to gain strength and become more fit.
Check with your doctor before starting an exercise program, and practice each exercise without any added weight first to ensure that you are using proper form. It is a good idea to get advice from an expert, such as a school coach or trainer, when first starting out. Have someone stand by or spot you any time you are lifting weights.