Eur J Appl Physiol (2000) 82: 112-116 Springer-Verlag 2000

Evaluation of the Lactate Pro blood lactate analyser

Abstract: 18 October 1999

An evaluation of the hand-held portable Lactate Pro Analyser (KDK) was undertaken to access its accuracy, reliability and versatility. Capillary blood samples were drawn from elite athletes in both laboratory and field settings and analysed in parallel.

Accuracy was determined in relation to three other lactate analysers:

  1. 1.The ABL 700 Series Acid-Base analyser (n=172 cases)

  2. 2.The Accusport Lactate Meter (n=118 cases)

  3. 3.The YSI 2300 Stat lactate analyser (n=22 cases)

  4. 4.The level of agreement was determined over the range of 1-18mM. The repeatability of results between two different Lactate Pro analysers was also determined over the same range. Versatility was assessed in the field, where the Lactate Pro analyser was used with elite athletes under a range of outdoor and indoor testing conditions.
    The correlations between the Lactate Pro and the ABL 700 Series Acid-Base analyser, YSI 2300 and Accusport were r = 0.98, r = 0.99, r = 0.97. the correlation between the two Lactate Pro analysers on the same sample (n = 96 cases) was r = 0.99.
    The level of agreement between the Lactate Pro and other analysers was generally less than + 2.0mM over the physiological range of 1.0-18.0mM (range of mean difference:
    -0.06mM to 0.52mM).
    The Lactate Pro was easy to operate and successfully completed the sample analysis in 100% of the tests performed. In summary, the Lactate Pro is accurate, reliable and exhibits a high degree of agreement with other lactate analysers.
    Key words Lactate – Lactate analysis – Reliability – Accuracy – Level of agreement
    Evaluation carried out by:
    D. B. Pyne – T. Boston – D.T.Martin
    Department of Physiology and Applied Nutrition
    Australian Institute of Sport, PO Box 176, Belconnen ACT 2616
    D.B.Pyne – D.T.Martin GADI Research Centre, University of Canberra, ACT.
    Canberra Australia email david.pyne@ausport.gov.au
    A. Logan Australian Swimming Inc., Canberra ACT Australia
    The measurement of blood lactate to assess and monitor exercise performance is a common practice in sports physiology laboratories worldwide. Lactate analyses is performed for the precision of training velocities performed for the prescription of training velocities (Madsen and Lohberg 1987; Prins 1988; Weltman 1993) to evaluate longitudinal changed in aerobic and anaerobic fitness (Sharp et al. 1984), and to evaluate individual responses to specific training sessions (Pyne 1989).
    Most of the prescriptive work is directed towards determination of the anaerobic threshold and estimation of the relative anaerobic contribution to exercise from lactate formation. Research has demonstrated a strong correlation between endurance performance and the anaerobic threshold determined from lactate profiling (Coyle 1995; Pfitzinger and Freedson 1998).

  5. 5.Athlete testing is often required in both laboratory and field settings. Irrespective of the location, the use of blood lactate measurements is dependent upon instrumentation that is accurate, linear and reliable.
    The ABL 700 series Acid-base analyser used in our laboratory is typical of large laboratory-based analysers that provide measurements of blood lactate, glucose, pH, bicarbonate and blood gas concentrations. The two most commonly used automated analysers in sports science laboratories are the Yellow Spring Instruments (YSI) 2300 Stat analyser and the Accusport lactate meter (Boehringer Mannheim). For widespread use in the laboratory and field, lactate analysers need to be portable, battery operated, capable of operating under a wide range of environmental conditions and able to process samples accurately, simply and quickly.
    Recently, the Lactate Pro, a portable, hand-held whole-blood lactate analyser has been released. The most direct competitor for the Lactate pro analyser is the Accusport Lactate Meter; both instruments are hand-held devices that take 60 seconds to measure the lactate concentration from a drop of blood placed on a reagent strip.
    Both the Accusport (Clough et al. 1997; Fell et al. 1998; Wigglesworth et al. 1996) and Lactate Pro (Makita 1997) analysers have been evaluated in preliminary laboratory based reports. Given the potential limitations of using correlational analyses alone, we combined this with the level of agreement statistical approach (Atkinson and Nevill 1998) to compare different analysers.
    The purpose of this investigation was to evaluate the suitability of the Lactate Pro for testing athletes in the field and to assess it accuracy against other laboratory and portable analysers.
    Male and female athletes aged between 16 and 30 years were recruited from a number of sporting teams at the Australian Institute of Sport in Canberra, Australia and an Australian Swimming National Team Camp in Darwin, Australia. Subjects signed Athlete Agreement documents; in accordance with the policies of the Australian Institute of Sport and, where appropriate, Australian Swimming Incorporated. Experimental procedures were approved by the Ethics Committee of the Australian Institute of Sport.
    Experimental design
    The accuracy of the Lactate Pro was determined in relation to two laboratory-based lactate analysers, the ABL 700 series and the YSI 2300 Stat analysers and one portable hand-held analyser: the Accusport Lactate Meter.
    For the purpose of this investigation the ABL 700 series was considered to be the criterion instrument. The laboratory participates in an external quality assurance program (QAP; Australian RCPA-AACB Chemical Pathology Quality Assurance Program, Flinders Medical Centre, South Australia) for blood glucose and lactate measurement with the ABL 700. The level of agreement between analysers was made over the range of 1-18 mM.
    Comparison between two different Lactate Pro Analysers (Lactate Pro 1 and 2) was made over the same range. Versatility was assessed in the field, where the Lactate Pro was used under a range of outdoor (18-30 degrees) and indoor (18-22 degrees) testing conditions with elite athletes. These temperatures are within the manufacturer’s prescribed operation range for both the Lactate Pro (10-40 degrees) and the Accusport (10-30 degrees) machines.
    The capillary blood samples necessary for comparison of the analysers were drawn from the following sporting groups;

  6. 6.Lactate Pro vs ABL 700, n = 172 cases, swimmers.

  7. 7.Lactate Pro vs YSI 2300, n = 22 cases, cyclists.

  8. 8.Lactate Pro vs Accusport, n = 118 cases, swimmers.

  9. 9.Lactate Pro 1 vs Lactate Pro 2, n = 96 cases, swimmers.

Exercise protocols

Blood lactate samples were taken in the laboratories from the cyclists during and after a progressive incremental cycle ergometer test to exhaustion. Samples taken from swimmers and analysed by the ABL 700 and Lactate Pro analysers were obtained during and after a 7x200 meter progressive incremental swimming test. Samples for the comparison of the Lactate Pro and Accusport Lactate Meter were taken from swimmers after routine interval-training sets. All capillary blood samples were taken within 30 seconds of the completion of each swim.

Lactate analysers

The Lactate Pro has recently been released by Akray (KDK) of Japan. It is a hand held portable analyser capable of measuring whole-blood lactate in the field. A small blood sample size of only 5m l is required. The reagent strip fills by capillary action directly from the earlobe of fingertip site. Lactate in the sample reacts with potassium ferricyanide and lactate oxidase to form potassium ferrocyanide and pyruvate.

Upon the application of a given voltage, ferrocyanide is oxidised, releasing electrons and creating a current. This current is measured amperometrically and is directly proportional to the lactate concentration of the blood sample. The Lactate Pro is supplied with a check strip (to confirm that the analysers is operating correctly) and a calibration strip that provides a non-quantitative indication of instrument accuracy.

The radiometer ABL 700 (Radiometer Copenhagen, Denmark) is a blood gas analyser that incorporates co-oximetry electrolyte and metabolite measurement. This analyser is designed for lavoratory use only and is not portable or suitable for field work. Lactate measurement by the ABL 700 requires a 75-m l capillary blood sample. Blood lactate passes across the outer layer of a multi-layered membrane and reacts with lactate oxidase that has been immobilised between the layers, to form pyruvate and H2 O2. The H2 O2 passes across the inner membrane, where it is subjected to a given potential and oxidised, creating a current that is measured directly proportional to the lactate concentration of the sample.

The ABL 700 was routinely calibrated every 4 hours, according to the manufacturer’s recommendations. Two of the four levels of control materials were analysed daily. The ABL 700 met all QAP performance standards for proportional bias, precision and linearity in lactate measurement during the study period. Three levels of quality control materials (Bio Rad) were analysed three times during the day.

The Accusport Lactate Meter (Boehringer Mannheim) is a portable hand-held analyser that requires between 10 and 25 m l of blood, employs a dry chemistry methodology and displays the result in 1 minute. The sample is applied to a reagent strip were lactate is converted to pyruvate and molybdenum blue via lactate oxidase. The molybdenum blue, which is proportional to the lactate concentration, is measured by reflectance photometry. The Accusport Lactate Meter was calibrated regularly at the beginning of each day and after every 20 sample with proprietary standards of known concentration (range 1.7-3,1 mM, and 4.5-7.0 mM).

The YSI 2300 Stat ( Yellow Springs Instruments, Ohio, USA) is a laboratory based analyser that measures both lactate and glucose from a 25-m l capillary blood sample. A platinum electrode is used to detect the production of H2 O2 from oxidation of the substrate. The H2 O2 is in turn oxidised, with the resulting electron flow being linearly proportional to the steady-state H2 O2, and therefore, to the concentration of the substrate (lactate). In contrast to the other three analysers, which employed a non-haemolysed whole-blood method, the blood samples for the YSI analysis were haemolysed (YSI 1515 Lysing Agent) and stabilised (YSI 2357 Buffer) before analysis. The YSI 2300 was calibrated regularly at the beginning of each day and after every 15 samples, with quality controls of known concentration (1.5 (0.2) and 7.5 (0.3) mM).

All analysers were cleaned, calibrated and operated in accordance with the manufacturer’s instructions. Blood samples were drawn from either the finger tip or earlobe of the swimmer or cyclist, with the standardised for a given athlete. Variation in sampling site is known to elicit different blood lactate concentrations (Foxdal et al. 1990,1991). All samples were analysed within 60 seconds of collection.

Statistical analysis

Comparison of analysers was achieved with Pearson product-moment correlation analysis, standard linear regression and the level of agreement. While correlation analysis indicates the degree to which two variables are associated, it does not necessarily indicate the extent to which values agree or disagree. To overcome this limitation, the approach of quantifying the level of agreement between two different analysers measuring the same parameter (in this case blood lactate concentration) was employed ( Atkinson and Nevill 1998). The mean difference between analysers (± 2 standard deviations or 95 % of a normally distributed population) was determined. Inspection of the slope and intercept of the linear regression was also undertaken to characterise the level of agreement between analysers.


The result for each analyser comparison are presented in two graphical formats. Firstly, each comparison is illustrated by correlational analysis, which shows the linear regression equation, the correlation coefficient and the 95% confidence intervals (Fig1: Lactate Pro vs ABL 700 series acid based analyser; Lactate Pro 1 vs Lactate Pro 2; Lactate Pro vs Accusport lactate meter; Lactate Pro vs YSI 2300 Stat).

Secondly, the level of agreement ( ± 2 standard deviations) between the Lactate Pro and each of the other analysers is shown in Fig. 2. (Lactate Pro vs ABL 700 series acid based analyser; Lactate Pro 1 vs Lactate Pro 2; Lactate Pro vs Accusport lactate meter; Lactate Pro vs YSI 2300 Stat).

The correlations between the Lactate Pro and the ABL 700 series acid based analyser, YSI 2300 and Accusport were r = 0.98, r = 0.99 and r = 0.97 respectively. The correlation between two different Lactate Pro analysers is analysing the same blood sample was r = 0.99. The agreement between each pair of analysers under analysers was generally less that ± 2.0 mM over the range of 1.0 – 18.0 mM (Table 1). The Lactate Pro successfully completed the sample analysis on 100% of the test performed. Although the YSI 2300 analyser uses a haemolysed blood sample for lactate determination, the comparative results with this analyser were similar to those obtained with the ABL 700 and Accusport.

The slope and intercept of the linear regression plots indicate the degree of agreement between the Lactate Pro and each of the other three analysers. The slope values in comparison with the Lactate Pro were 1.008, 1.192 and 1.062 for the ABL 700 series acid based analyser, Accusport and YSI 2300 Stat, respectively (fig1). Essentially, these results indicate that the values provided by the Lactate Pro are in good agreement with those provided by both the ABL 700 series and the YSI 2300 analysers. However the level of agreement with the Accusport Lactate Meter deteriorates at lactate values higher than 8.0 mM (fig 2). Above this level, there is clear evidence that the Accusport reads lower than the Lactate Pro. For example, at a Lactate Pro reading of 10.0mM the Accusport read only 9.0mM, and when the Lactate Pro read 16.0mM, the Accusport read only 14.0mM.


The results obtained is this evaluation support the use of the Lacate Pro as an accurate and reliable lactate analyser in the field. The strong correlations ( r > 0.96) between the Lactate Pro and existing analysers (ABL 700, YSI 2300 and the Accusport Lactate Meter) and the limits of agreement less than 2.0mM through the physiological range of 1.0 – 18.0mM underline the suitability of the Lactate Pro. These results support the preliminary findings of Makita (1997), who also demonstrated a strong relationship (r =0.99) against the Accusport (n = 313 cases).

The lacate values obtained in this evaluation were generally less then 18.0mM, and consequently the statistical treatment of the data is only applicable to that limit. This evaluation had not addressed the issue of linearity beyond the 18.0mM lactate concentration that may occur in some sports such as sprint running and track cycling. However in most sports blood lactate levels do not often exceed this level (Lowenstein et al. 1994; Telford et al. 1988), and the Lactate Pro is therefor suitable for all the majority of field applications across a wide range of sports. Future studies may address the specific instances where blood lactate values exceed 18.0mM.

The "limits of agreement" analysis (Altman and Bland 1983) was introduced as a measure of absolute reliability, to overcome some of the limitations associated with the standard error of the mean (SEM) and coefficient of variation (CV). The results of this preliminary evaluation show that the results produced by the Lactate Pro appear to be homeoscedastic (ie there appears to be no obvious relationship between the degree of disparity between analysers and level of lactate measured).

This is in contrast to the Accusport Lactate Meter, which exhibits a degree of heteroscedasticity where values in excess of 8mM appear to be substantially lower than in other analysers and this difference increases with increasing levels of blood lactate concentration.

The lactate Pro requires a sample of size of only 5 m l and does not require and pipetting of blood onto the reagent strip. This eliminates the potential mental error related to pipetting and facilitates a more rapid measurement. Initial indications are that the Lactate Pro can analyse a sample and displays the result approximately 30 seconds more quickly than the Accusport.

Both the Accusport and Lactate Pro were highly reliable in completing blood lactate analyses, although the test strip with the Accusport occasionally needed to be inserted two or three times before being accepted. Handling the protective foil cover surrounding the reagent strip with the Lactate Pro takes some practice, but is eventually quite straight forward.

In summary, this evaluation has shown that the Lactate Pro exhibits a high degree of accuracy with other lactate analysers, good reliability and a high degree of versatility under a variety of testing conditions.

The above information was provided to Eur J Appl Physiol (2000) 82: 112-116 and completed by David B Pyne – Tanya Boston – David T. Martin – Andrew Logan.


The authors with to acknowledge the assistance and cooperation of the coaches and athletes of the Australian Swimming Team, the Australian Women’s Cycling Team, and staff of the Department of Physiology and Applied Nutrition, Australian Institute of Sport.

The Lactate Pro Analysers were kindly provided by KDK, Japan. The authors also thank Dr Allan Hahn of the Australian Institute of Sport, for his assistance with the statistical analysis and preparation of the manuscript.


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