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High intensity exercise decreases global brain glucose uptake in humans
Jukka Kemppainen1, Sargo Aalto, Toshihiko Fujimoto
1Turku PET Centre, University of Turku, PO Box 52, 20521 Turku, Finland.
The Journal of Physiology
|July 23, 2005
Summary
High intensity exercise reduces brain glucose uptake, suggesting the brain uses other fuels like lactate for energy. Exercise capacity may influence this metabolic adaptation in specific brain regions.
Area of Science:
- Neuroscience
- Exercise Physiology
- Metabolism
Background:
- Physiological activation enhances local brain glucose uptake.
- The impact of high-intensity exercise on global and regional brain glucose uptake remains unclear.
Purpose of the Study:
- To directly measure the effects of exercise intensity and capacity on brain glucose uptake.
- To investigate substrate utilization in the brain during high-intensity exercise.
Main Methods:
- Positron emission tomography (PET) with [18F]fluoro-deoxy-glucose ([18F]FDG) was used.
- Fourteen healthy men underwent 35-minute bicycle exercise at 30%, 55%, and 75% of VO2max on separate days.
- PET scans were performed after exercise completion.
Main Results:
- Regional glucose metabolic rate (rGMR) decreased in cortical regions with increasing exercise intensity.
- Global brain glucose uptake decreased by 32% from low to high intensity exercise.
- Higher exercise capacity was associated with a more pronounced decrease in glucose uptake in the anterior cingulate cortex.
Conclusions:
- Brain glucose uptake declines as exercise intensity increases.
- The brain likely utilizes substrates like lactate to meet energy demands during high-intensity exercise.
- Exercise training may induce adaptive metabolic changes in frontal cortical regions.