Adaptations to short-term high-fat diet persist during exercise despite high carbohydrate availability
Burke, Louise M., Hawley, John A., Angus, Damien, Cox, Gregory, Clark, Sally A., Cummings, Nicola K., Desbrow, Ben and Hargreaves, Mark 2002, Adaptations to short-term high-fat diet persist during exercise despite high carbohydrate availability, Medicine and science in sports and exercise, vol. 34, no. 1, pp. 83-91.
Attached Files
(Some files may be inaccessible until you login with your Deakin Research Online credentials)
Name
Description
MIMEType
Size
Downloads
Title
Adaptations to short-term high-fat diet persist during exercise despite high carbohydrate availability
Purpose: Five days of a high-fat diet produce metabolic adaptations that increase the rate of fat oxidation during prolonged exercise. We investigated whether enhanced rates of fat oxidation during submaximal exercise after 5 d of a high-fat diet would persist in the face of increased carbohydrate (CHO) availability before and during exercise.
Methods: Eight well-trained subjects consumed either a high-CHO (9.3 g·kg-1·d-1 CHO, 1.1 g·kg-1·d-1 fat; HCHO) or an isoenergetic high-fat diet (2.5 g·kg-1·d-1 CHO, 4.3 g·kg-1·d-1 fat; FAT-adapt) for 5 d followed by a high-CHO diet and rest on day 6. On day 7, performance testing (2 h steady-state (SS) cycling at 70% peak O2 uptake [[latin capital V with dot above]O2peak] + time trial [TT]) of 7 kJ·kg-1) was undertaken after a CHO breakfast (CHO 2 g·kg-1) and intake of CHO during cycling (0.8 g·kg-1·h-1).
Results: FAT-adapt reduced respiratory exchange ratio (RER) values before and during cycling at 70% [latin capital V with dot above]O2peak; RER was restored by 1 d CHO and CHO intake during cycling (0.90 ± 0.01, 0.80 ± 0.01, 0.91 ± 0.01, for days 1, 6, and 7, respectively). RER values were higher with HCHO (0.90 ± 0.01, 0.88 ± 0.01 (HCHO > FAT-adapt, P < 0.05), 0.95 ± 0.01 (HCHO > FAT-adapt, P < 0.05)). On day 7, fat oxidation remained elevated (73 ± 4 g vs 45 ± 3 g, P < 0.05), whereas CHO oxidation was reduced (354 ± 11 g vs 419 ± 13 g, P < 0.05) throughout SS in FAT-adapt versus HCHO. TT performance was similar for both trials (25.53 ± 0.67 min vs 25.45 ± 0.96 min, NS).
Conclusion: Adaptations to a short-term high-fat diet persisted in the face of high CHO availability before and during exercise, but failed to confer a performance advantage during a TT lasting ~ 25 min undertaken after 2 h of submaximal cycling.