| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Received January 14, 2005
Revised February 7, 2005
Accepted after revision February 7, 2005
1 Faculty of Kinesiology and Rehabilitation sciences (University of Leuven)
2 Copenhagen Muscle Research Centre
3 Clinique Romande de Réadaption, Sion, Switzerland
4 Exercise Physiology and Biomechanics Laboratory, Leuven, Belgium
5 Clinique Romnade de Réadaption, Sion, Switzerland
6 Gynaecology and Obstetrics Unit, Faculty of Medicine, Leuven, Belgium
* To whom correspondence should be addressed. E-mail: katrien.debock{at}faber.kuleuven.be.
The effect of exercise in the fasted state, versus exercise with high rate carbohydrate intake, on intramyocellular triglyceride (IMTG) and glycogen content was investigated. According to a randomized crossover study design, nine young healthy volunteers (n=9) participated in two experimental sessions with an interval of 3 weeks. In each session subjects performed 2 hours of constant-load bicycle exercise (~75% VO2max), followed by 4 hours of controlled recovery. On one occasion they exercised after an overnight fast (F). On the other occasion (CHO) they received carbohydrates before (~150g) and during (1gkg-1 bwhr-1) exercise. In either condition, subjects ingested 5gcarbohydrates per kg bw during recovery. Fibre type-specific relative IMTG content was determined by oil-red-oil staining in needle biopsies from m. vastus lateralis before, immediately after and 4hr after exercise. During F but not during CHO, the exercise bout decreased IMTG content in type I fibres from 18 ± 2% to 6 ± 2% (p=0.007). Conversely, during recovery, IMTG in type I fibres decreased from 15 ± 2% to 10 ± 2% in CHO, but did not change in F. Neither exercise nor recovery changed IMTG in type IIa fibers in any experimental condition. Exercise-induced net glycogen breakdown was similar between F and CHO. However, compared with CHO (11.0±7.8 mmolkg-1hr-1), mean rate of postexercise muscle glycogen resynthesis was 3-fold greater in F (32.9±2.7 mmolkg-1hr-1, p=0.01). Furthermore, oral glucose loading during recovery increased plasma insulin markedly more in F (+46.80 µUml-1) than in CHO (+14.63 µUml-1, p=0.02). We conclude that IMTG breakdown during prolonged submaximal exercise in the fasted state takes place in type I fibers predominantly and that this breakdown is prevented in the CHO-fed state. Furthermore, facilitated glucose-induced insulin secretion may contribute to enhanced muscle glycogen resynthesis following exercise in the fasted state.
This article has been cited by other articles:
|
|
 |
|
  K. De Bock, W. Derave, B. O. Eijnde, M. K. Hesselink, E. Koninckx, A. J. Rose, P. Schrauwen, A. Bonen, E. A. Richter, and P. Hespel Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake J Appl Physiol, April 1, 2008; 104(4): 1045 - 1055. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. De Bock, T. Dresselaers, B. Kiens, E. A. Richter, P. Van Hecke, and P. Hespel Evaluation of intramyocellular lipid breakdown during exercise by biochemical assay, NMR spectroscopy, and Oil Red O staining Am J Physiol Endocrinol Metab, July 1, 2007; 293(1): E428 - E434. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Stellingwerff, H. Boon, R. A. M. Jonkers, J. M. Senden, L. L. Spriet, R. Koopman, and L. J. C. van Loon Significant intramyocellular lipid use during prolonged cycling in endurance-trained males as assessed by three different methodologies Am J Physiol Endocrinol Metab, June 1, 2007; 292(6): E1715 - E1723. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. De Bock, W. Derave, M. Ramaekers, E. A. Richter, and P. Hespel Fiber type-specific muscle glycogen sparing due to carbohydrate intake before and during exercise J Appl Physiol, January 1, 2007; 102(1): 183 - 188. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. S. Lee-Young, M. J. Palmer, K. C. Linden, K. LePlastrier, B. J. Canny, M. Hargreaves, G. D. Wadley, B. E. Kemp, and G. K. McConell Carbohydrate ingestion does not alter skeletal muscle AMPK signaling during exercise in humans Am J Physiol Endocrinol Metab, September 1, 2006; 291(3): E566 - E573. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. B. Jorgensen, E. A. Richter, and J. F. P. Wojtaszewski Role of AMPK in skeletal muscle metabolic regulation and adaptation in relation to exercise J. Physiol., July 1, 2006; 574(1): 17 - 31. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Kiens Skeletal Muscle Lipid Metabolism in Exercise and Insulin Resistance Physiol Rev, January 1, 2006; 86(1): 205 - 243. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
