Lactate Testing: Equipment, Analysis and Outcomes
Lactate Threshold Testing:
The Equipment Behind the Numbers
A lactate profile is one of the most powerful tools in endurance sport — but only if the data it produces is accurate. The analyser used to measure your blood lactate directly influences the training zones you will be given. Here is what that means in practice.
Lactate threshold testing sits at the heart of evidence-based endurance training. Unlike VO₂ max — which describes your physiological ceiling — lactate thresholds describe the intensities at which you actually train most effectively, and they are superior to VO₂ max for differentiating performance among trained athletes at similar fitness levels.
But the threshold data you receive is only as precise as the analyser used to measure your blood lactate at each stage of the test. An analyser that under-reads lactate concentrations — particularly at higher intensities — will shift your calculated thresholds upward, producing training zones that are too aggressive. Train in those zones consistently and you risk chronic overreaching. This is not a theoretical concern; it is a mathematically demonstrable consequence of analyser bias, and it is well documented in the peer-reviewed literature.
Why Lactate Threshold Supersedes VO₂ Max for Training Prescription
VO₂ max tells you the size of your aerobic engine. Lactate thresholds tell you how efficiently you can operate that engine — and at what intensity the wheels begin to fall off. For the overwhelming majority of athletes, the limiting factor in endurance performance is not their absolute VO₂ max ceiling but their ability to sustain high fractions of that ceiling without accumulating lactate at a rate that forces them to slow down.
Two threshold points are of particular practical importance:
LT1 (First Lactate Threshold) — the first sustained, meaningful rise in blood lactate above resting values. This marks the upper boundary of true aerobic base training, the intensity that should dominate the majority of your training volume. Training just below LT1 develops mitochondrial density, fat oxidation capacity, and aerobic efficiency without the accumulated physiological stress of higher intensities.
LT2 (Second Lactate Threshold / Maximal Lactate Steady State) — the intensity at which lactate production begins to exceed clearance capacity and concentrations rise rapidly. This corresponds closely to race pace for events lasting approximately 30–70 minutes, and defines the upper boundary of sustainable high-intensity work. Threshold and tempo training is prescribed in relation to this point.
"Lactate thresholds are considered superior to VO₂ max for differentiating endurance performance among elite athletes — but that superiority depends entirely on the accuracy of the measurement."
The critical implication is this: small systematic errors in blood lactate measurement — even errors of 1–2 mmol/L — can shift both threshold points by several watts or seconds per kilometre when the lactate curve is analysed. Those shifts produce different training zones. Different training zones produce different training stimuli. The accuracy of the tool used to measure your blood therefore has a direct downstream effect on the quality of your training prescription.
The Fixed Threshold Problem: Why 2 and 4 mmol/L Are Inadequate
A persistent and frustrating shortcut in lactate testing is the use of fixed absolute thresholds — most commonly 2 mmol/L as a surrogate for LT1 and 4 mmol/L as a surrogate for LT2. These figures have been embedded in training literature for decades, and many commercial testing protocols still use them uncritically.
The problem is that these values are population averages, not individual physiological landmarks. Resting blood lactate varies between individuals from approximately 0.5 to 2.0 mmol/L. An athlete with a resting value of 1.8 mmol/L will show an apparent threshold at a concentration that is physiologically meaningless when a 2 mmol/L cutoff is applied. Highly trained endurance athletes often sustain substantial exercise intensities before lactate rises meaningfully above resting — their LT2 may occur at concentrations well above or below 4 mmol/L depending on their individual buffering characteristics, training history, and the sport being tested.
Fixed absolute thresholds (2 and 4 mmol/L) are a historical simplification, not a physiological law. Any laboratory applying these cutpoints without considering individual resting values, the shape of the lactate curve, and the specific detection methodology is producing threshold estimates rather than true individual thresholds. At Athlete Lab, we apply an individualised rate-of-change methodology to each athlete's lactate curve — this produces LT1 and LT2 values that reflect genuine physiological transitions, not population-average approximations.
Blood Lactate Analysers: A Research-Based Comparison
The accuracy and reliability of portable blood lactate analysers has been studied systematically, most rigorously in a landmark study by Bonaventura and colleagues at the Australian Institute of Sport, published in the Journal of Sports Science and Medicine (2015). This study compared five portable analysers and one point-of-care device against a laboratory-grade criterion analyser — the Radiometer ABL90 — across a lactate range of approximately 1–23 mmol/L, using venous blood samples from subjects at rest and during graded exercise.
The study evaluated each analyser across five lactate concentration bands (0–1.9, 2–4.9, 5–9.9, 10–14.9, and >15 mmol/L) and used root mean squared error (√MSE) — a combined measure of reliability and bias — as the primary performance metric. The findings are directly relevant to how a laboratory should choose and use its equipment.
| Analyser | Error <15 mmol/L | Error >15 mmol/L | Overall Rating | Notes |
|---|---|---|---|---|
| Edge Athlete Lab | Low (~0–2 mmol/L) | Low–Moderate | Preferred | Best overall portable performance; low bias through most of the physiological range; preferred for threshold testing |
| Lactate Pro2 Athlete Lab | Low–Moderate | Low (best portable at >15) | Preferred | Excellent precision at high lactate; preferred for peak lactate capture and Dmax-based LT2 calculations |
| Nova StatStrip Xpress | Low (~0–2 mmol/L) | High (~6–10 mmol/L error) | Conditional | Good for clinical / resting range; poor at high intensities; shifted LT2 23W below criterion in cycling data |
| Lactate Pro (original) | Moderate | High (~4–8 mmol/L error) | Not recommended | Significant negative bias above 5 mmol/L; overestimates LT2 in rowing by up to 18W vs criterion |
| Lactate Scout+ | Moderate | High (~4–6 mmol/L error) | Not recommended | Largest negative bias at high concentrations; overestimates LT2 in rowing by up to 18W vs criterion |
| i-STAT (point-of-care) | Lowest of all | Lowest of all | Excellent (impractical) | Laboratory-grade accuracy in handheld format; 280s analysis time and high cost make it impractical for routine sport testing |
At Athlete Lab, we use both the Edge and Lactate Pro2 — the two portable analysers independently identified as the most accurate options for athlete testing in this research. The Edge performs optimally through the physiological range most relevant to threshold identification (1–15 mmol/L), while the Lactate Pro2 provides the best portable accuracy at the high lactate concentrations required for peak lactate capture and Dmax-based LT2 calculation.
What the Research Reveals About Analyser Bias
The most consistent finding across all portable analysers in the Bonaventura study was a tendency to under-read blood lactate relative to the criterion — a negative bias that became substantially more pronounced at concentrations above 10–15 mmol/L. Understanding why this matters requires understanding how LT2 is calculated.
The modified Dmax method — one of the most validated approaches to LT2 identification — uses the peak lactate value achieved during a maximal test to construct a reference line against which the lactate curve is compared. If the analyser under-reads peak lactate by 2–6 mmol/L (as was observed with the Lactate Pro, Scout+, and Xpress in the AIS study), the reference point shifts downward and the calculated LT2 shifts upward in intensity — producing training zones that are systematically too hard.
An 18-watt overestimation of LT2 in a rower is not a rounding error — it is the difference between threshold training and overreaching. Multiplied across weeks and months of training prescription, a systematically biased analyser can meaningfully compromise an athlete's preparation. This is why equipment selection for lactate testing is not a minor operational detail. It is a clinical decision.
The study found that biological variation in blood lactate during exercise is the dominant source of variability — greater than analytical error for all analysers tested. This means that within a well-controlled protocol using a quality analyser, the uncertainty in your threshold results is driven more by normal physiological day-to-day variation than by the measurement device itself. The practical implication: the best way to minimise uncertainty in threshold data is consistent pre-test standardisation of conditions (nutrition, rest, hydration, time of day) — not just equipment selection alone.
Sources of Error in Lactate Testing
Even with validated, high-accuracy analysers, a number of procedural and biological variables can introduce meaningful error into lactate test results. Understanding these allows you to evaluate whether a testing protocol is genuinely rigorous.
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Sampling site and technique Fingertip capillary blood is the standard for sport science lactate testing. Earlobe blood has been used historically but requires different reference ranges. Venous samples, while used in research, are impractical in field testing. Critically, the first drop of blood should be discarded — it is contaminated by tissue fluid and will systematically under-read lactate concentration. Insufficient pressure on the sampling site and inadequate blood flow also compromise sample quality.
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Sample-to-analysis delay Blood lactate in capillary tubes changes over time after collection, particularly at high concentrations — the AIS study demonstrated a decay of approximately 0.05 mmol/L per minute in samples above 10 mmol/L. Samples should be analysed within 30–60 seconds of collection. Any laboratory with a workflow that involves queuing samples or batching analysis introduces time-dependent error into their data.
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Environmental temperature Portable lactate analyser test strips are temperature-sensitive. Performance in hot or cold conditions can differ from laboratory conditions. The AIS study was conducted at 22–24°C — testing in significantly different ambient temperatures, or leaving strips in a cold bag, may affect analyser accuracy. Strips should be stored and used within manufacturer-specified temperature ranges.
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Strip storage and expiry Test strips for electrochemical lactate analysers are calibration-sensitive consumables. Using expired strips, strips that have been exposed to excessive humidity, or strips from an opened vial that has been left unsealed compromises the enzyme integrity and produces inaccurate readings. This is a surprisingly common source of error in busy testing environments.
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Mixing different analyser units between sessions The AIS study found that two devices of the same brand were generally interchangeable — with one notable exception: the Lactate Pro showed statistically significant between-device variation. The study's recommendation is that where possible, the same physical unit of an analyser should be used consistently across all testing sessions for a given athlete, particularly if thresholds are to be compared longitudinally.
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Inappropriate stage duration or increment size A lactate profile requires each stage to reach a genuine metabolic steady state before sampling. Stages that are too short (under 3–4 minutes for most protocols) capture transitional lactate values that do not reflect the true physiological response to that intensity. This causes the lactate curve to appear blunted or delayed, shifting apparent thresholds to higher intensities. Conversely, overly long stages in highly trained athletes can result in fatigue-driven lactate accumulation that misrepresents the underlying aerobic capacity.
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Pre-test nutritional and physiological state Carbohydrate availability directly affects lactate dynamics — a fasted athlete will show a lower, right-shifted lactate curve; a high-carbohydrate pre-load may elevate early-stage values. Prior exercise, sleep deprivation, caffeine, and hydration status each modulate the curve independently of training adaptation. Without standardised and verified pre-test conditions, repeat testing cannot reliably detect real training-induced changes.
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Threshold identification methodology Once the data is collected, the method used to identify LT1 and LT2 from the lactate curve introduces its own layer of variability. Fixed absolute cutpoints (2 and 4 mmol/L), visual inspection, the Dmax method, the modified Dmax method, log–log transformation, and individualised rate-of-change approaches all produce different threshold intensities from the same underlying data. A laboratory that applies different methods between sessions — or that does not document which method was used — cannot reliably track change over time.
What a Rigorous Lactate Test Protocol Looks Like
A well-designed lactate testing protocol is not simply a matter of pricking a finger at intervals during exercise. The following elements distinguish a clinically rigorous protocol from one that is operationally convenient but physiologically compromised.
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1Pre-test standardisation Athlete arrives with verified nutritional status, no prior intense exercise in 24–48 hours, consistent hydration, and no caffeine or alcohol in the preceding 12 hours. Time of day is standardised where repeat testing is planned. These conditions are documented, not assumed.
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2Individualised protocol design Stage duration (typically 3–5 minutes per stage) and increment size are selected based on the athlete's sport, fitness level, and previous test history. The protocol should produce 6–10 usable data points across the full physiological range, with at least 3–4 points below LT1 and capture of peak or near-peak lactate.
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3Sample collection at end of each stage Capillary blood sampled from fingertip at the final 30 seconds of each stage, after the first drop has been discarded and adequate blood flow is established. Sample transferred to the analyser immediately — no queuing, no batching.
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4Concurrent physiological monitoring Heart rate recorded at end of each stage (or averaged over final minute). Power output (cycle) or speed/gradient (running) recorded precisely. RPE documented at each stage. This concurrent data allows the lactate curve to be expressed as a function of multiple intensity metrics — essential for translating thresholds into real-world training targets.
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5Validated, documented threshold identification LT1 and LT2 identified using a consistent, validated methodology applied to each individual's curve — not fixed absolute values. The method used, the supporting physiological criteria (RER, heart rate, RPE where available), and the specific threshold intensities are all documented in the athlete's record.
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6Training zone derivation and athlete communication Training zones calculated from threshold data using consistent methodology, expressed in the metrics relevant to the athlete's training (power, pace, heart rate). The zones and the physiological rationale behind them are explained in a written report the athlete can refer back to and take to their coach.
The Analysers Used at Athlete Lab
Equipment decisions at Athlete Lab are grounded in the peer-reviewed evidence on analyser accuracy. We use two complementary devices — selected specifically because independent research identifies them as the most accurate portable options for athlete testing.
Validated as one of the two portable analysers with lowest total error across the 1–15 mmol/L range most relevant to threshold identification. The AIS study found total error of approximately 0–2 mmol/L through this range — the best performance of any portable device tested.
The Edge uses an electrochemical biosensor with a StatStrip multi-well design that corrects for interfering substances including haematocrit variation — an important advantage in a population of athletes whose haematocrit may differ significantly from general population norms.
Identified alongside the Edge as one of the two preferred portable analysers for athlete testing — particularly at high concentrations above 15 mmol/L where most other portable devices show substantial negative bias. This is critical for Dmax-based LT2 calculations, which depend on accurate peak lactate capture.
The Lactate Pro2 supersedes the original Lactate Pro with improved accuracy, and represents the next generation of Arkray's field-validated platform used in sports science laboratories worldwide.
The AIS research recommends using the same physical analyser unit consistently across sessions for a given athlete to minimise between-device variability. At Athlete Lab, we track which devices are used in each session and maintain device-specific records, so that longitudinal data comparison is not confounded by device-switching.
Questions to Ask Before Booking a Lactate Test
An informed athlete asks better questions. The following represent the minimum standard of enquiry when evaluating a lactate testing facility:
- Which specific analyser do you use, and has it been independently validated?
- How do you identify LT1 and LT2 — fixed thresholds or individual curve analysis?
- How long is each stage, and how is protocol duration individualised?
- What pre-test conditions do you require, and how are they verified?
- Do you use the same analyser unit consistently for my repeat tests?
- Is the test conducted by someone qualified in exercise physiology?
- Are thresholds reported in power, pace, and heart rate?
- Will I receive a written report explaining my zones and how to apply them?
- How are my results tracked and compared across testing sessions?
- Can results be integrated with my VO₂ max and other physiological data?
"The number a lactate test produces is only half the story. The other half is the rigour of the methodology used to produce it — and the expertise applied to translate it into training that actually works."
