Which test should I do?
Three protocols, three different questions. Use this to choose before you set up the equipment.
LT1, LT2 and the lactate curve
The foundational assessment. Maps the full relationship between power and lactate from easy to hard. Gives you LT1 (the first threshold — aerobic baseline), LT2 (the second threshold — onset of heavy accumulation), and pinpoints the power at fixed blood lactate concentrations. Best for setting training zones, tracking aerobic development, and identifying where your curve sits relative to your FTP.
When: Start of season, mid-season review, after a training block. Every 6–12 weeks if tracking closely.
Requires: Power meter, lactate analyser, ~90 min.
Maximal Lactate Steady State
Confirmation protocol. The Step Test suggests where your threshold is; the MLSS test confirms it. Rides at a sustained power for 10-minute stages and checks whether lactate stabilises or accumulates. MLSS is the highest power at which blood lactate does not rise more than 1 mmol/L between 3 and 9 minutes. Directly comparable to FTP as a sustainable power ceiling.
When: After a Step Test to confirm LT2. Before a major target event.
Requires: Estimated MLSS from Step Test, power meter, lactate analyser, ~50 min.
Anaerobic glycolytic capacity
Measures VLaMax — the maximum rate of lactate production — via a 20-second all-out sprint. Combined with VO2max, gives a metabolic fingerprint: whether the athlete is aerobically dominant, anaerobically dominant, or balanced. Informs training emphasis (more or less glycolytic work), discipline suitability, and energy system contribution calculations.
When: Annual metabolic profiling. After a sustained training block focused on either aerobic base or sprint power.
Requires: Lactate analyser, optional VO2max value, ~40 min.
Pre-test checklist
Consistency between tests matters as much as the test itself. Results are only comparable if conditions are controlled.
- No caffeine, alcohol, or nicotine
- No high-intensity training
- A restful night's sleep
- Normal carbohydrate intake
- Calibrate lactate analyser
- Same time of day as previous tests
- Fast for at least 1 hour before
- No caffeine, alcohol, or nicotine (24 hr)
- Room temperature controlled where possible
- Warm up as prescribed per protocol
- Sign waiver and weigh before test
- Fingertip or earlobe, not forearm
- Clean and dry before puncture
- Discard first drop of blood
- Consistent sampling timing across stages
- Record at exactly the right minute
- Log ambient temperature
Interpreting results
Fixed lactate thresholds vs. individual methods
The 2 mmol/L and 4 mmol/L benchmarks are population averages — useful reference points but not universally accurate. Baseline lactate varies widely between athletes (0.5–2.0 mmol/L at rest). An athlete with a high aerobic capacity may not accumulate to 4 mmol/L until well above LT2. Always interpret fixed-concentration values alongside individual methods (Baseline +0.5, ModDmax).
Lactate curve shape
A well-trained aerobic athlete shows a flat curve for most of the test with a sharp upward inflection at high power — the "hockey stick." A less aerobically trained athlete shows a gradual upward slope from early stages. Over time, successful aerobic training shifts the curve rightward: the same lactate level occurs at a higher power, which is the measurable sign of adaptation.
Incremental Step Test
9 steps at fixed percentages of FTP. First step is doubled in duration to allow lactate to stabilise. Enter heart rate and blood lactate at the end of each step. Results update in real time.
Maximal Lactate Steady State
Confirm your sustainable power ceiling. Each stage is 10 minutes with lactate sampled at 3 and 9 minutes. MLSS is the highest power at which the rise between samples stays at or below 1 mmol/L. Start at your estimated MLSS minus 10 W — the Step Test LT2 is a good starting point.
VLaMax — Anaerobic Glycolytic Capacity
A 20-second maximal sprint, then blood lactate at 3, 5, 7, and 20 minutes post-effort. VLaMax = (peak lactate − baseline) ÷ 16. Combine with VO2max for a full metabolic fingerprint.
VLaMax Results
Energy system profile
Lactate clearance
Training zones from lactate data
Auto-populated from your Step Test and MLSS results. You can also enter values manually. Zones are anchored to your individual physiological thresholds rather than FTP percentages, which makes them more accurate for low-intensity and threshold work.
Power zones
Heart rate zones
Testing history
Log each test as you go. The trend across sessions is the coaching signal — not any single number. Save a session in the toolbar above and it appears here automatically, or log manually.
Evidence base
The calculations and threshold definitions in this tool are grounded in peer-reviewed exercise physiology literature.
Lactate threshold methods
Sjodin & Jacobs (1981) — Onset of blood lactate accumulation and marathon running performance. International Journal of Sports Medicine, 2(1), 23–26. Origin of the 4 mmol/L (OBLA) threshold concept.
Faude, Kindermann & Meyer (2009) — Lactate threshold concepts: How valid are they? Sports Medicine, 39(6), 469–490. Comprehensive review of threshold methods. Demonstrates that no single method is universally superior; individual methods outperform fixed concentrations in well-trained athletes.
Heck et al. (1985) — Justification of the 4 mmol/L lactate threshold. International Journal of Sports Medicine, 6(3), 117–130. Original study underpinning the 4 mmol standard; also establishes its limitations in highly trained populations.
Cheng et al. (1992) — A new approach for the determination of ventilatory and lactate thresholds. International Journal of Sports Medicine, 13(7), 518–522. Original description of the Dmax method used to identify LT2.
Bishop, Jenkins & Mackinnon (1998) — The relationship between plasma lactate parameters, Wpeak and 1-h cycling performance in women. Medicine & Science in Sports & Exercise, 30(8), 1270–1275. Baseline + 0.5 mmol/L method for LT1.
MLSS
Beneke (2003) — Methodological aspects of maximal lactate steady state. European Journal of Applied Physiology, 89(1), 95–99. Defines the 1 mmol/L criterion used in this tool. Classic MLSS paper.
Beneke & von Duvillard (1996) — Determination of maximal lactate steady state response in selected sports events. Medicine & Science in Sports & Exercise, 28(2), 241–246. MLSS practical determination across cycling and other sports.
Billat et al. (2003) — The concept of maximal lactate steady state: a bridge between biochemistry, physiology and sport science. Sports Medicine, 33(6), 407–426. Positions MLSS as equivalent to the critical power concept.
VLaMax and anaerobic capacity
Mader & Heck (1986) — A theory of the metabolic origin of anaerobic threshold. International Journal of Sports Medicine, 7(S1), S45–S65. Origin of the VLaMax concept and the calculation used here (lactate rise / time constant).
Weigend et al. (2021) — Estimation of maximal lactate production rate using a 15-second all-out test. Frontiers in Physiology. Validation of short sprint protocols for VLaMax estimation.
Hauser et al. (2014) — Comparison of calculated and experimental maximal lactate steady state in cyclists. International Journal of Sports Physiology and Performance, 9(5), 825–831. Cross-validation of VLaMax with MLSS in trained cyclists.
Lactate clearance
Brooks (1985) — The lactate shuttle during exercise and recovery. Medicine & Science in Sports & Exercise, 18(3), 360–368. Foundational paper on lactate metabolism and clearance between tissues.
Menzies et al. (2010) — Blood lactate clearance during active recovery after an intense running bout depends on the intensity of the active recovery. Journal of Sports Sciences, 28(9), 975–982. Clearance rate methodology.