| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Turku PET Centre
4 Department of Medicine, University of Turku, 20521 Turku, Finland
2 Department of Psychology, Åbo Akademi University, 20500 Turku, Finland
3 Department of Medicine and Science in Sports and Exercise, Graduate School of Medicine, University of Tohoku, Sendai, Japan
Physiological activation increases glucose uptake locally in the brain. However, it is not known how high intensity exercise affects regional and global brain glucose uptake. The effect of exercise intensity and exercise capacity on brain glucose uptake was directly measured using positron emission tomography (PET) and [18F]fluoro-deoxy-glucose ([18F]FDG). Fourteen healthy, right-handed men were studied after 35 min of bicycle exercise at exercise intensities corresponding to 30, 55 and 75% of 
on three separate days. [18F]FDG was injected 10 min after the start of the exercise. Thereafter exercise was continued for another 25 min. PET scanning of the brain was conducted after completion of the exercise. Regional glucose metabolic rate (rGMR) decreased in all measured cortical regions as exercise intensity increased. The mean decrease between the highest and lowest exercise intensity was 32% globally in the brain (38.6 ± 4.6 versus 26.1 ± 5.0 µmol (100 g)–1 min–1, P < 0.001). Lactate availability during exercise tended to correlate negatively with the observed brain glucose uptake. In addition, the decrease in glucose uptake in the dorsal part of the anterior cingulate cortex (37%
versus 20%, P < 0.05 between 30% and 75% of 
) was significantly more pronounced in subjects with higher exercise capacity. These results demonstrate that brain glucose uptake decreases with increase in exercise intensity. Therefore substrates other than glucose, most likely lactate, are utilized by the brain in order to compensate the increased energy needed to maintain neuronal activity during high intensity exercise. Moreover, it seems that exercise training could be related to adaptive metabolic changes locally in the frontal cortical regions.
(Received 25 May 2005;
accepted after revision 19 July 2005;
first published online 21 July 2005)
Corresponding author J. Knuuti: Turku PET Centre, University of Turku, PO Box 52, 20521 Turku, Finland. Email: juhani.knuuti{at}tyks.fi
This article has been cited by other articles:
|
|
 |
|
  T. S. Larsen, P. Rasmussen, M. Overgaard, N. H. Secher, and H. B. Nielsen Non-selective {beta}-adrenergic blockade prevents reduction of the cerebral metabolic ratio during exhaustive exercise in humans J. Physiol., June 1, 2008; 586(11): 2807 - 2815. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. H. Secher, T. Seifert, and J. J. Van Lieshout Cerebral blood flow and metabolism during exercise: implications for fatigue J Appl Physiol, January 1, 2008; 104(1): 306 - 314. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Volianitis, A. Fabricius-Bjerre, A. Overgaard, M. Stromstad, M. Bjarrum, C. Carlson, N. T. Petersen, P. Rasmussen, N. H. Secher, and H. B. Nielsen The cerebral metabolic ratio is not affected by oxygen availability during maximal exercise in humans J. Physiol., January 1, 2008; 586(1): 107 - 112. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. H Secher and B. Quistorff Brain glucose and lactate uptake during exhaustive exercise J. Physiol., October 1, 2005; 568(1): 3 - 3. [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
