For Overweight Teens, Is Aerobic or Resistance Exercise Better?

By Dan Peterson, TeamSnap's Sports Science Expert

For most teenagers who are overweight, the road to a more healthy weight is not a mystery. “Eat fewer calories and exercise more” is a mantra they’ve had preached to them for years. If only parents and coaches could be more specific about the right type of exercise. Aerobic activities? Resistance activities? How about both but in what proportion? Two new research studies looked closely at which works better.  

Having more than doubled in children and tripled in adolescents, obesity has become a major health concern in the United States over the past 30 years, according to the Centers for Disease Control and Prevention. About 80% of kids who are obese continue to be overweight into their adult years.

"Obesity is an epidemic among youth," says Dr. Ron Sigal of the University of Calgary's Institute for Public Health and Libin Cardiovascular Institute of Alberta. "Adolescents who are overweight are typically advised to exercise more, but there is limited evidence on what type of exercise is best in order to lose fat."

To help provide some guidance, Sigal and his peers at the University of Calgary and the University of Ottawa recruited 304 local, overweight teens, ages 14 to 18 from the Healthy Eating Aerobic and Resistance Training in Youth (HEARTY) study to compare different approaches. Divided into four groups, all were given the same diet counseling on health eating habits but varied their exercise routines. Over a 22-week period, the first group did only resistance type exercises, including weight machines and free weights; the second group stuck only to aerobic activities, like walking, running and biking; the third group combined both resistance and aerobic workouts; and the last group added no exercise at all.

The three exercise groups were asked to work out four times per week, monitored by personal trainers. At the end of each week, each participant had his or her body fat percentage measured using an MRI scan.

All three groups that exercised showed significant improvement in body fat percentage over the diet only group. However, the researchers discovered that the combination of aerobic and resistance training had the biggest impact by far.

"Remarkably, among participants who completed at least 70 per cent of the prescribed exercise sessions, waist circumference decreased close to seven centimeters in those randomized to combined aerobic plus resistance exercise, versus about four centimeters in those randomized to do just one type of exercise, with no change in those randomized to diet alone,” said co-principal researcher Dr. Glen Kenny of the University of Ottawa. “The body fat percentage decreased significantly more in those who did combined aerobic and resistance exercise than in those who only did aerobic exercise.”

The research has been published in the Journal of the American Medical Association - Pediatrics.

However, with the busy schedules of teens and their parents, fitting both aerobic and resistance training into their day is not always feasible. If forced to pick just one, which type of workout is best? To find out, SoJung Lee of the Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine and her colleagues asked 44 obese girls, ages 14 to 18, to join one of three test groups. The first group did 60 minutes of aerobic exercise three days per week for three months. The second group did resistance training for the same frequency and duration. The third group acted as a control group, doing no exercise during the same period.

As with the first study, those kids that exercised lost more body fat than doing nothing at all.  However, the aerobic group showed a significantly greater improvement in body fat percentage than the resistance-training group. In addition, the researchers found that teenage girls seemed to enjoy aerobic workouts more than weightlifting. Of course, motivation is key to maintaining a consistent schedule of exercise.

So, which is better? If time permits, doing both aerobic and resistance training is best. However, when there aren’t enough hours in the day, at least try to squeeze in an aerobic workout.