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December 17, 2003

Effect of Exercise Intensity on Body Composition—ReplyEffect of Exercise Intensity on Body Composition—Reply

Author Affiliations

Letters Section Editor: Stephen J. Lurie, MD, PhD, Senior Editor.

JAMA. 2003;290(23):3069. doi:10.1001/jama.290.23.3069-a

In Reply: I agree with Drs Ritt and Lechleitner that exercise may have a significant impact on fat-free mass. However, in our study we were attempting to examine exercise intensity while holding exercise volume constant. Therefore, it is possible that exercise intensity does not have differential effects on body weight or body composition when total exercise volume is held constant. Our results are consistent with the findings of the study published by Duncan et al1 who found no difference in body composition with varying intensities of exercise when exercise volume was held constant across the different intensities. Moreover, based on our review of the literature, a reduction of energy intake of 500 to 1000 kcal/d combined with increased exercise intensity is not consistently related to increases in fat-free mass, irrespective of either endurance or resistance forms of exercise.2 Thus, our findings appear to be consistent with the majority of clinical trials. However, I agree that body composition data may provide additional insight into the potential mechanism by which exercise plays a role in the management of body weight.