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Cerebral metabolism during upper and lower body exercise
Mads K Dalsgaard1, Stefanos Volianitis, Chie C Yoshiga
1Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. madskd@tiscali.dk
Journal of Applied Physiology (Bethesda, Md. : 1985)
|June 23, 2004
Summary
Exercise requiring significant mental effort reduces the brain's metabolic ratio of oxygen to glucose and lactate. This effect is observed regardless of whether the exercise involves the legs or arms, though arm cranking shows a smaller reduction.
Area of Science:
- Exercise Physiology
- Neuroscience
- Metabolic Research
Background:
- Exercise that demands significant volitional effort is associated with a decreased cerebral metabolic ratio of oxygen to glucose and lactate.
- This reduction is most pronounced at the point of exhaustion during physical activity.
- Previous research suggests arm exercise requires greater effort than leg exercise.
Purpose of the Study:
- To test the hypothesis that the cerebral metabolic ratio reduction is more pronounced during arm cranking compared to leg exercise.
- To investigate the influence of different exercise paradigms on cerebral metabolism during exhaustive exercise.
Main Methods:
- Evaluated cerebral arterial-venous differences for blood gases, glucose, and lactate in two groups of eight subjects.
- Subjects underwent exhaustive arm cranking and leg exercise protocols.
- Measurements were taken at baseline, 10 minutes into exercise, and at exhaustion.
Main Results:
- Leg exercise reduced the cerebral metabolic ratio from 5.6 to 3.3 at exhaustion.
- Arm cranking also decreased the ratio, but to a lesser extent, from 6.7 to 4.7 at exhaustion.
- The reduction in the cerebral metabolic ratio was significantly smaller during arm cranking than during leg exercise.
Conclusions:
- Exercise requiring conscious effort decreases the cerebral metabolic ratio, irrespective of the muscle groups used.
- The exercise paradigm influences the magnitude of this metabolic change, with arm cranking showing a less pronounced reduction.
- Cerebral metabolic adjustments during exercise are dependent on the specific demands of the activity.