Journal of Applied Physiology, Vol 62, Issue 5 1975-1981, Copyright © 1987 by American Physiological Society

ARTICLES

Blood lactate concentration increases as a continuous function in progressive exercise

R. L. Hughson, K. H. Weisiger and G. D. Swanson

The relationship between arterialized blood lactate concentration [( La-]) and O2 uptake (VO2) was examined during a total of 23 tests by eight subjects. Exercise was on a cycle ergometer with work rate incremented from loadless pedaling to exhaustion as a 50-W/min ramp function. Two different mathematical models were studied. One model employed a log-log transformation of [La-] and VO2 to yield [La-] threshold as proposed by Beaver et al. (J. Appl. Physiol. 59: 1936-1940, 1985). The other model was a continuous exponential plus constant of the form La- = a + b[exp(cVO2)]. In 21 of 23 data sets, the mean square error (MSE) of the continuous model was less than that of the log-log model (P less than 0.001). The MSE was on average 3.5 times greater in the log-log model than in the continuous model. The residuals were randomly distributed about the line of best fit for the continuous model. In contrast, the log-log model showed a nonrandom pattern indicating an inappropriate model. As an index of the position of the [La-]-VO2 continuous model, the VO2 at which the rate of increase of [La-] equaled the rate of increase of VO2 (d[La-]/dVO2 = 1) was determined. This VO2 was 2.241 +/- 0.081 l/min, which averaged 64.6% of maximal VO2. It is proposed that this lactate slope index could be used as a relative indicator of fitness instead of the previously applied threshold concept. The change in [La-] could be better described mathematically by a continuous model rather than the threshold model of Beaver et al.

This article has been cited by other articles:

				V. Manzi, C. Castagna, E. Padua, M. Lombardo, S. D'Ottavio, M. Massaro, M. Volterrani, and F. Iellamo Dose-response relationship of autonomic nervous system responses to individualized training impulse in marathon runners Am J Physiol Heart Circ Physiol, June 1, 2009; 296(6): H1733 - H1740. [Abstract] [Full Text] [PDF]

				G. H. Raymer, H. J. Green, D. A. Ranney, G. D. Marsh, and R. T. Thompson Muscle metabolism and acid-base status during exercise in forearm work-related myalgia measured with 31P-MRS J Appl Physiol, April 1, 2009; 106(4): 1198 - 1206. [Abstract] [Full Text] [PDF]

				C. Liu, J. Wu, J. Zhu, C. Kuei, J. Yu, J. Shelton, S. W. Sutton, X. Li, S. J. Yun, T. Mirzadegan, et al. Lactate Inhibits Lipolysis in Fat Cells through Activation of an Orphan G-protein-coupled Receptor, GPR81 J. Biol. Chem., January 30, 2009; 284(5): 2811 - 2822. [Abstract] [Full Text] [PDF]

				B. Kay Common misconceptions perpetuated Advan Physiol Educ, September 1, 2008; 32(3): 244 - 245. [Full Text] [PDF]

				L. M. Redman, G. C. Scroop, G. Westlander, and R. J. Norman Effect of a Synthetic Progestin on the Exercise Status of Sedentary Young Women J. Clin. Endocrinol. Metab., July 1, 2005; 90(7): 3830 - 3837. [Abstract] [Full Text] [PDF]

				M. Roussel, J. P. Mattei, Y. Le Fur, B. Ghattas, P. J. Cozzone, and D. Bendahan Metabolic determinants of the onset of acidosis in exercising human muscle: a 31P-MRS study J Appl Physiol, March 1, 2003; 94(3): 1145 - 1152. [Abstract] [Full Text] [PDF]

				ATS/ACCP Statement on Cardiopulmonary Exercise Testing Am. J. Respir. Crit. Care Med., January 15, 2003; 167(2): 211 - 277. [Full Text] [PDF]

				A. G. Thin, S. J. Linnane, E. F. McKone, R. Freaney, M. X. FitzGerald, C. G. Gallagher, and P. McLoughlin Use of the Gas Exchange Threshold to Noninvasively Determine the Lactate Threshold in Patients With Cystic Fibrosis* Chest, June 1, 2002; 121(6): 1761 - 1770. [Abstract] [Full Text] [PDF]