Fitness: Overweight Kids Need Less Intense Exercise to Optimize Weight Loss

Dixie Iverson for PE Update.com

A recent study cited in the British Journal of Sports Medicine indicates that requiring overweight or obese students to exercise at the same intensity as their leaner peers may be counterproductive to their weight loss efforts.

Study Findings
Researchers tested the fat-burning rate of thirty twelve-year-old boys by having them cycle at increasing intensities.. Seventeen of the subjects were obese, while the rest were lean. The test was intended to find the rate of exercise that caused the students to burn the most fat (Fat Max).

Results showed that the lean boys and their overweight counterparts had very different fat burning rates. Lean boys reached a high level of fat burning when they were pedaling at about 50% to 60% of capacity. This equates to a moderate level of exercise intensity.

Obese boys, on the other hand, reached their highest Fat Max level while pedaling at about 30% - a much lower level of intensity. Their Fat Max remained steady until they drew near to 50%, at which point it dropped dramatically.

Application for PE Classes
This study indicates that asking obese or overweight children to work as hard as their fitter classmates may actually reduce their ability to lose weight. This is because heavy children reach their maximum fat burning potential at a lower level of intensity than their peers.

The authors of the study suggest that this may be because obese people have a higher number of "fast twitch" or Type 2 muscle fibres, which burn more carbohydrates with exercise. On the other hand, slim people have a higher proportion of Type 1 fibres that burn more fat.

References:
1. "Overweight Kids Need Less Intensive Exercise for Effective Weight Loss, Study Suggests, ScienceDaily.com 10/08. http://www.sciencedaily.com /releases/2008/03/080331221148.htm
2. Zunquin G, Theunynck D, Sesboue B, Arhan P, Bougle D., "Comparison of fat oxidation during exercise between lean and obese pubertal boys: clinical implications." British Journal of Sports Medicine, Online First, April 2, 2008.

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