Aerobic Exercise
A teen’s fitness program should include aerobic exercise such as brisk walking, basketball, bicycling, swimming, in-line skating, soccer, jogging—any continuous activity that increases heart rate and breathing. Regular workouts improve the efficiency of the cardiorespiratory system, so that the heart and lungs don’t have to work as hard to meet the body’s increased demands for freshly oxygenated blood.
Aerobic exercise also affects body weight composition, by burning excess calories that would otherwise get converted to fat. In general, the more aerobic an activity, the more calories are expended. For instance, if a teenager weighing 132 pounds walks at a moderate pace for ten minutes, he burns forty-three calories. Running instead of walking more than doubles the amount of energy spent, to ninety calories.
Low-intensity workouts burn a higher percentage of calories from fat than high-intensity workouts do. However, the more taxing aerobic exercises ultimately burn more fat calories overall. One study compared the burn rates for a thirty-minute walk at three and a half miles per hour and a thirty-minute run at seven miles per hour. The walking group expended an average of 240 calories. Two-fifths came from fat, and three-fifths came from carbohydrates, for a total of ninety-six fat calories. In the running group, the ratio of fat energy burned versus carbohydrate energy burned was significantly less: one to four. Yet overall, the runners consumed 450 calories. Total number of fat calories burned: 108.
Weight Training
Under the guidance of well-trained adults, children aged eight or older can safely incorporate weight training (also called strength training and resistance training) into their workouts to increase muscle strength and muscle endurance. Muscle strength refers to the ability to displace a given load or resistance, while muscle endurance is the ability to sustain less-intense force over an extended period of time. Males will not be able to develop large muscles until after puberty. Females generally are not able to develop large muscle mass. They do not have to worry about getting too muscular.
The Proper Technique: Less Weight, More Reps
Multiple studies show that young people gain strength and endurance faster by lifting moderately heavy weights many times rather than straining to hoist unwieldy loads for just a few repetitions.
Teens should always be supervised by a qualified adult, who can help them and demonstrate the proper technique. For that reason, it’s safer to work out at school or at a health club than on home exercise equipment. Other precautions to take include the following:
See your pediatrician for a physical and medical checkup before your youngster starts training.
Remember that resistance training is a small part of a well-rounded fitness program. Experts generally recommend that adolescents exercise with weights no more than three times a week.
Don’t overdo it (part 1): Excessive physical activity can lead to injuries and cause menstrual abnormalities. Your teenager may be exercising too much if her weight falls below normal or her muscles ache. Complaints of pain warrant a phone call to your pediatrician.
Don’t overdo it (part 2): Teens should be reminded not to step up the weight resistance and number of repetitions before they’re physically ready. Getting in shape takes time.
Drink plenty of fluids when exercising. Young people are more susceptible to the effects of heat and humidity than adults. Teens’ ability to dissipate heat through sweating is not as efficient as adults. The Centers for Disease Control and Prevention recommends that teens drink at least two six-ounce glasses of water before, during and after working out in steamy conditions.
Always warm up and cool down with stretching exercises before and after training. Stretching the muscles increases their flexibility: the ability to move joints and stretch muscles through a full range of motion, and the fourth component of physical fitness. It also helps safeguard against injury.