Background: Children with Crohn's disease (CD) suffer from malnutrition. Understanding substrate utilization during exercise may help patients with CD sustain a healthy active lifestyle without compromising nutrition. The aim of this study was to determine whether substrate utilization and bioavailability during exercise are altered in children with CD compared with controls.
Methods: Seven children with CD (mean age ± SD: 15.2 ± 2.3 yr) and 7 controls (14.4 ± 2.3 yr) were matched by sex and biological age. Participants completed 60 minutes of cycling at an intensity equivalent to 50% of their peak mechanical power. Rates of total fat and carbohydrate (CHO) oxidation, the amount of fat and CHO oxidized, and the contribution of fat and CHO to total energy expenditure were calculated from expired gases collected during exercise. Blood was collected before, during, and at the end of exercise and analyzed for insulin, free fatty acids, and glucose.
Results: Whole-body fat oxidation rate (expressed in mg · kg−1 of body weight per min) during exercise was lower in children with CD (5.8 ± 1.0) compared with controls (8.0 ± 2.2, P < 0.05). Children with CD relied significantly more on CHO, with approximately 10% greater contribution toward total energy expenditure (P < 0.05) than controls. There were no differences in plasma insulin, free fatty acids, or glucose between the groups.
Conclusions: Fat metabolism during exercise seems to be impaired in children with CD. A greater reliance on CHO is required to meet the energy demands of submaximal exercise.
Article first published online 7 October 2013
*Child Health & Exercise Medicine Program, McMaster University, Hamilton, Ontario, Canada;
†Department of Rehabilitation, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands;
‡McMaster Children’s Hospital, Hamilton, Ontario, Canada;
§Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada; and
‖University Medical Center Utrecht, Utrecht, The Netherlands.
Reprints: Brian W. Timmons, PhD, Child Health & Exercise Medicine Program, McMaster University 1280 Main Street West, HSC 3N27G Hamilton, ON, Canada (e-mail: firstname.lastname@example.org).
This study was funded by a Natural Sciences and Engineering Research Council of Canada Discovery Grant awarded to B.W. Timmons.
The authors have no conflicts of interest to disclose.
Received August 26, 2013
Accepted August 26, 2013