Thanh Nguyen1, Joyce Obeid1, Jeff M Baker2, Tim Takken3, Linda Pedder4, Gianni Parise2, Brian W Timmons5. 1. Child Health & Exercise Medicine Program, Department of Pediatrics, McMaster University, Hamilton, ON, Canada. 2. Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, ON, Canada; Department of Kinesiology, McMaster University, Hamilton, ON, Canada. 3. Child Health & Exercise Medicine Program, Department of Pediatrics, McMaster University, Hamilton, ON, Canada; Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands. 4. Cystic Fibrosis Clinic, McMaster Children's Hospital, Hamilton, ON, Canada. 5. Child Health & Exercise Medicine Program, Department of Pediatrics, McMaster University, Hamilton, ON, Canada. Electronic address: timmonbw@mcmaster.ca.
Abstract
BACKGROUND: Exercise is a viable form of therapy for children with cystic fibrosis (CF). Understanding the energy sources used during exercise would aid CF patients in obtaining proper nutrition in order to sustain an active lifestyle. METHODS: Six boys with CF (mean age ± SD: 14.8 ± 2.3 yrs, FEV1: 99 ± 18% predicted) and six matched controls (14.0 ± 2.2 yrs) completed a session of two 30 min bouts of cycling at an intensity set at 50% peak mechanical power. Rates of total fat and carbohydrate (CHO) oxidation were calculated from expired gases. Plasma insulin, glucose and free fatty acid (FFA) were determined before, during and at the end of the exercise. RESULTS: Rates of fat oxidation (expressed in mean mg × kg body weight(-1) × min(-1) ± SD) were significantly lower in children with CF (5.7 ± 1.6) compared to controls (8.6 ± 1.8, p < 0.05). Children with CF also had lower values than controls in amount of fat oxidized (CF: 17.3 ± 5.0 g, controls: 26.1 ± 5.9 g, p < 0.05) and percent of total energy expenditure from fat (CF: 32 ± 6%, controls: 43 ± 7%, p < .0.05), but a higher contribution from CHO (CF: 68 ± 6%, controls: 57 ± 7% p < .0.05). Plasma FFA was significantly lower in children with CF compared to controls during (CF: 252.5 ± 117.9 μM, controls: 602.2 ± 295.6) and at the end of exercise (CF: 430.9 ± 180.6, controls: 1147.5 ± 473.5). There were no differences in the rates of CHO oxidation, insulin or glucose between groups. CONCLUSION: Fat metabolism during exercise is impaired in boys with CF and may be attributed to an inability to mobilize FFA.
BACKGROUND: Exercise is a viable form of therapy for children with cystic fibrosis (CF). Understanding the energy sources used during exercise would aid CF patients in obtaining proper nutrition in order to sustain an active lifestyle. METHODS: Six boys with CF (mean age ± SD: 14.8 ± 2.3 yrs, FEV1: 99 ± 18% predicted) and six matched controls (14.0 ± 2.2 yrs) completed a session of two 30 min bouts of cycling at an intensity set at 50% peak mechanical power. Rates of total fat and carbohydrate (CHO) oxidation were calculated from expired gases. Plasma insulin, glucose and free fatty acid (FFA) were determined before, during and at the end of the exercise. RESULTS: Rates of fat oxidation (expressed in mean mg × kg body weight(-1) × min(-1) ± SD) were significantly lower in children with CF (5.7 ± 1.6) compared to controls (8.6 ± 1.8, p < 0.05). Children with CF also had lower values than controls in amount of fat oxidized (CF: 17.3 ± 5.0 g, controls: 26.1 ± 5.9 g, p < 0.05) and percent of total energy expenditure from fat (CF: 32 ± 6%, controls: 43 ± 7%, p < .0.05), but a higher contribution from CHO (CF: 68 ± 6%, controls: 57 ± 7% p < .0.05). Plasma FFA was significantly lower in children with CF compared to controls during (CF: 252.5 ± 117.9 μM, controls: 602.2 ± 295.6) and at the end of exercise (CF: 430.9 ± 180.6, controls: 1147.5 ± 473.5). There were no differences in the rates of CHO oxidation, insulin or glucose between groups. CONCLUSION: Fat metabolism during exercise is impaired in boys with CF and may be attributed to an inability to mobilize FFA.