Blood lactate measurements and analysis during exercise: a guide for clinicians

Abstract

Blood lactate concentration ([La(-)](b)) is one of the most often measured parameters during clinical exercise testing as well as during performance testing of athletes. While an elevated [La(-)](b) may be indicative of ischemia or hypoxemia, it may also be a "normal" physiological response to exertion. In response to "all-out" maximal exertion lasting 30-120 seconds, peak [La(-)](b) values of approximately 15-25 mM may be observed 3-8 minutes postexercise. In response to progressive, incremental exercise, [La(-)](b) increases gradually at first and then more rapidly as the exercise becomes more intense. The work rate beyond which [La(-)](b) increases exponentially [the lactate threshold (LT)] is a better predictor of performance than V O2max and is a better indicator of exercise intensity than heart rate; thus LT (and other valid methods of describing this curvilinear [La(-)](b) response with a single point) is useful in prescribing exercise intensities for most diseased and nondiseased patients alike. H(+)-monocarboxylate cotransporters provide the primary of three routes by which La(-) transport proceeds across the sarcolemma and red blood cell membrane. At rest and during most exercise conditions, whole blood [La(-)] values are on average 70% of the corresponding plasma [La(-)] values; thus when analyzing [La(-)](b'), care should be taken to both (1) validate the [La(-)](b)-measuring instrument with the criterion/reference enzymatic method and (2) interpret the results correctly based on what is being measured (plasma or whole blood). Overall, it is advantageous for clinicians to have a thorough understanding of [La(-)](b) responses, blood La(-) transport and distribution, and [La(-)](b) analysis.

Keywords: lactate analyzers; lactate threshold; maximal lactate; onset of blood lactate accumulation; plasma; whole blood.

Figures

Figure 1.

A typical [La−]b response to a progressive, incremental exercise test. LT represents the “lactate threshold.” These are whole blood measurements corrected for water content. Used (redrawn) with permission from Smith EW, Skelton MS, Kremer DE, Pascoe DD, Gladden LB. Lactate distribution in the blood during progressive exercise. Med Sci Sports Exerc. 1997 May;29(5):654-60.

Figure 2.

Lactate threshold (LT) measurement. (A) An example of the visual method using raw data and (B) utilizing a log-log transformation. V˙O2=O2 uptake/consumption. V˙O2 is a linear function of work rate. Used (redrawn) with permission from Beaver WL, Wasserman K, Whipp BJ. Improved detection of lactate threshold during exercise using a log-log transformation. J Appl Physiol. 1985 Dec;59(6):1936-40.

Figure 3.

Dmax method. Refer to text for explanation. V˙O2=O2 uptake/consumption. VO2 is a linear function of work rate. Used (redrawn) with permission from Cheng B, Kuipers H, Snyder AC, Keizer HA, Jeukendrup A, Hesselink M. A new approach for the determination of ventilatory and lactate thresholds. Int J Sports Med. 1992 Oct;13(7):518-22; Georg Thieme Verlag KG.

Figure 4.

(1) Visual LT, (2) Dmax LT (LTD), and (3) OBLA. Note that each provides a different V˙O2, although all three are highly correlated with each other. V˙O2=O2 uptake/consumption. V˙O2 is a linear function of work rate. Used (redrawn) with permission from Gladden LB. Lactate metabolism during exercise In: Poortmans JR, editor. Principles of exercise biochemistry. 3rd ed. Basel: Karger; 2004. p. 152-96.

Figure 5.

Schematic examples of [La−]b responses at MLSS for three different, hypothetical subjects. [La−]b at the MLSS may be as low as 1.5 mM or as high as 7.0 mM; the average is ≈3.7 mM.

Figure 6.

[La−]b response to 60 seconds of “all-out” maximal exercise. Peak values are typically observed 3–8 minutes postexercise. Unpublished data from Smith, Skelton, Kremer, Pascoe, and Gladden. Plotted point “X” demonstrates a very high [La−]b (26.0 mM) observed for a subject in a similar study.

Figure 7.

Schematic view of La− rate of appearance (Ra), La− rate of disappearance (Rd), and resulting [La−]b during progressive, incremental exercise. Used (redrawn) with permission from Brooks GA. Anaerobic threshold: review of the concept and directions for future research. Med Sci Sports Exerc. 1985 Feb;17(1):22-34.

Figure 8.

Correlation of endurance performance with LT. (A) 5,000-m run time vs LT, (B) 10,000-m run time vs LT, and (C) 10-mile run time vs LT. LT is presented as the V˙O2 (O2 uptake/consumption) at which the LT occurred. Used (redrawn) with permission from Kumagai S, Tanaka K, Matsuura Y, Matsuzaka A, Hirakoba K, Asano K. Relationships of the anaerobic threshold with the 5 km, 10 km, and 10 mile races. Eur J Appl Physiol. 1982;49(1):13-23 (Figure 4).

Figure 9.

Schematic showing differences between a “good runner” and a “poor runner” in terms of the [La−]b response to progressive incremental exercise. Used (redrawn) with permission from Kumagai S, Tanaka K, Matsuura Y, Matsuzaka A, Hirakoba K, Asano K. Relationships of the anaerobic threshold with the 5 km, 10 km, and 10 mile races. Eur J Appl Physiol. 1982;49(1):13-23 (Figure 3).

Figure 10.

Well-trained ischemic heart disease patients exhibit an LT that is 100% of V˙O2max. In this study, “Trained Normals”' and “Trained Patients” exhibit similar performance ability because their absolute LT values are similar. Percentages inside of histograms indicate LT as a percentage of O2max; numbers in parentheses indicate the absolute V˙O2 (mL. kg-1. min-1) at LT. Used (redrawn) with permission from Coyle EF, Martin WH, Ehsani AA, Hagberg JM, Bloomfield SA, Sinacore DR, Holloszy JO. Blood lactate threshold in some well-trained ischemic heart disease patients. J Appl Physiol. 1983 Jan;54(1):18-23.

Figure 11.

Schematic representing the transport of La− across RBC membranes. Used (redrawn) with permission from Poole RC, Halestrap AP. Transport of lactate and other monocarboxylates across mammalian plasma membranes. Am J Physiol. 1993 Apr;264(4 Pt 1):C761-82.

Figure 12.

Whole blood [La−] versus corresponding plasma [La−]; SD, standard deviation of the ratio of whole blood [La−] to plasma [La−]. N = 324 blood samples. Unpublished data from Dobson, Smith, and Gladden.

Figure 13.

(A) Comparison of the Dr. Lange LP8+ [La−] analyzer with the criterion/reference enzymatic photofluorometric method. (B) Comparison of the Lactate Pro [La−] analyzer with the criterion/reference enzymatic photofluorometric method. See text for full explanation. Used (redrawn) with permission from Medbø JL, Mamen A, Holt Olsen O, Evertsen F. Examination of four different instruments for measuring blood lactate concentration. Scand J Clin Lab Invest. 2000 Aug;60(5):367-80.