J Appl Physiol 102: 2408, 2007.
First published March 22, 2007; doi:10.1152/japplphysiol.00287.2007
8750-7587/07 $8.00
POINT-COUNTERPOINT COMMENTS
Comment on Point:Counterpoint: The lactate paradox does/does not occur during exercise at high altitude"
George A. Brooks
Integrative Biology
University of California
gbrooks{at}berkeley.edu
The following letter is in response to the Point:Counterpoint "The lactate paradox does/does not occur during exercise at high altitude" that appears in this issue.
To the Editor: The exchange between Drs. West and van Hall (8, 9) is unsatisfying. West's (9) paper is classic, but incomplete. And while anachronism may explain Dr. van Hall's (8) dire response, his behavior should not be supported by the Journal of Applied Physiology. So far as I know, there has been only one attempt to determine the effects of acute and chronic altitude exposure on lactate kinetics that imposed appropriate dietary controls to distinguish between hypoxia and cachexia (2). West did not reference any of the papers, whereas van Hall cited some of the body of work, but chose to ignore the results. Seemingly, van Hall ignored the results because he has no understanding of the Lactate Shuttle (1), a concept that has received cross-disciplinary support (7). Hence, he cannot understand our findings that working muscle beds can simultaneously produce and consume lactate (3), diverse tissues can produce lactate for consumption by working muscle (4), and the sympathetic nervous system greatly influences carbohydrate metabolism at altitude (5). As summarized previously by Reeves (6), our results are (and should be) different from those of van Hall et al. because they gave no consideration to the necessity of controlling diet and body mass, which is essential (2), rendering their data uninterpretable. We showed by means of tracers and (a-v) measurements that lactate flux is increased on acute altitude because sympathetic nervous system (SNS) activity is increased and that with time at altitude lactate flux and SNS activity decrease.
REFERENCES
- Brooks GA. Lactate shuttles in nature. Biochem Soc Trans 30: 258–264, 2002.[CrossRef][ISI][Medline]
- Brooks GA, Butterfield GE. Metabolic response of lowlanders to high altitude exposure: malnutrition vs. the effect of hypoxia. In: Lung Biology in Health and Disease, High Altitude, edited Hornbein T and Schoene B. New York: Dekker, 2001, p. 569–600.
- Brooks GA, Butterfield GE, Wolfe RR, Groves BM, Mazzeo RS, Sutton JR, Wolfel EE, Reeves JT. Decreased reliance on lactate during exercise after acclimatization to 4,300 m. J Appl Physiol 71: 333–341, 1991.[Abstract/Free Full Text]
- Brooks GA, Wolfel EE, Butterfield GE, Cymerman A, Roberts AC, Mazzeo RS, Reeves JT. Poor relationship between arterial [lactate] and leg net release during steady-rate exercise at 4,300 m altitude. Am J Physiol Regul Integr Comp Physiol 275: R1192–R1201, 1998.[Abstract/Free Full Text]
- Mazzeo RS, Bender PR, Brooks GA, Butterfield GE, Groves BM, Sutton JR, Wolfel EE, Reeves JT. Arterial catecholamine responses during exercise with acute and chronic high-altitude exposure. Am J Physiol Endocrinol Metab 261: E419–E424, 1991.[Abstract/Free Full Text]
- Reeves JT, Wolfel EE, Green HJ, Mazzeo RS, Young AJ, Sutton JR, Brooks GA. Oxygen transport during exercise at high altitude and the lactate paradox: lessons from Operation Everest II and Pikes Peak. In: Exercise and Sport Sciences Reviews, vol. 20. New York: Williams and Wilkins, 1992, p. 275–296.
- Schurr A. Lactate: the ultimate cerebral oxidative energy substrate. J Cereb Blood Flow Metab 26: 142–152, 2006.[CrossRef][ISI][Medline]
- Van Hall G. Counterpoint: The lactate paradox does not occur during exercise at high altitude. J Appl Physiol. In press.
- West J. Point: The lactate paradox does occur during exercise at high altitude. J Appl Physiol. In press.
Copyright © 2007 by the American Physiological Society.
