HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 97/5/1733    most recent 00450.2004v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Dalsgaard, M. K. Articles by Secher, N. H. Search for Related Content PubMed PubMed Citation Articles by Dalsgaard, M. K. Articles by Secher, N. H.

Cerebral metabolism during upper and lower body exercise

Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark

Submitted 28 April 2004 ; accepted in final form 15 June 2004

When continuation of exercise calls for a "will," the cerebral metabolic ratio of O₂ to (glucose + lactate) decreases, with the largest reduction (30–50%) at exhaustion. Because a larger effort is required to exercise with the arms than with the legs, we tested the hypothesis that the reduction in the cerebral metabolic ratio would become more pronounced during arm cranking than during leg exercise. The cerebral arterial-venous differences for blood-gas variables, glucose, and lactate were evaluated in two groups of eight subjects during exhaustive arm cranking and leg exercise. During leg exercise, exhaustion was elicited after 25 ± 6 (SE) min, and the cerebral metabolic ratio was reduced from 5.6 ± 0.2 to 3.5 ± 0.2 after 10 min and to 3.3 ± 0.3 at exhaustion (P < 0.05). Arm cranking lasted for 35 ± 4 min and likewise decreased the cerebral metabolic ratio after 10 min (from 6.7 ± 0.4 to 5.0 ± 0.3), but the nadir at exhaustion was only 4.7 ± 0.4, i.e., higher than during leg exercise (P < 0.05). The results demonstrate that exercise decreases the cerebral metabolic ratio when a conscious effort is required, irrespective of the muscle groups engaged. However, the comparatively small reduction in the cerebral metabolic ratio during arm cranking suggests that it is influenced by the exercise paradigm.

arm cranking; central fatigue; cerebral metabolism; lactate

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]

				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]

				S. Ogoh, P. J. Fadel, R. Zhang, C. Selmer, O. Jans, N. H. Secher, and P. B. Raven Middle cerebral artery flow velocity and pulse pressure during dynamic exercise in humans Am J Physiol Heart Circ Physiol, April 1, 2005; 288(4): H1526 - H1531. [Abstract] [Full Text] [PDF]