Determining thresholds in a lactate test
The lactate test module determines two thresholds: the aerobic threshold (LT1) and the anaerobic threshold (LT2, also called AT). You pick the method per threshold yourself, or you set the threshold manually on the curve.
The two thresholds
- LT1 (aerobic threshold): the point where lactate first rises above your resting value. The line between easy endurance work and the first real effort.
- LT2 (anaerobic threshold / AT): the point above which lactate builds up faster than your body can clear it. The line that drives your threshold and tempo training.
For each threshold you pick a method from a dropdown on the Analysis tab. Every method comes with a short explanation, and the recommended choice is marked.
LT1 methods
| Method | How it works |
|---|---|
| Baseline | Threshold placed where lactate first measurably rises above your individual resting value. Conservative, for example during rehabilitation or for beginners. |
| Baseline +0.4 | Resting value + 0.4 mmol/L. Slightly more conservative than +0.5, useful with a very low baseline lactate. |
| Baseline +0.5 (recommended) | Resting value + 0.5 mmol/L. The most commonly used scientific method and the best default for most athletes. |
| 2.0 mmol/L | Fixed threshold, regardless of your resting value. A quick reference, less accurate at the individual level. |
| Manual | You identify the inflection point on the curve yourself. |
LT2 methods
| Method | How it works |
|---|---|
| D-Max | The point with the greatest perpendicular distance to the line between the first and last data point. Works well for a complete test to exhaustion. May overestimate if the test stopped too early. |
| D-Max Modified (recommended) | Same principle, but the line starts where lactate begins to rise. This filters out the low resting steps and gives a more accurate result. Best default for most tests. |
| Tangent 51° | Draws a tangent to the curve at 51°. Simple and reproducible, but less individual because the angle is fixed. |
| Stegmann IAT | Determines the individual anaerobic threshold from both the exercise and recovery phases. Requires lactate measurements during recovery after the test. |
| 4.0 mmol/L | Fixed threshold (OBLA, Onset of Blood Lactate Accumulation). A quick reference, less accurate at the individual level. |
| Manual | You identify the inflection point on the curve yourself. |
💡 Stegmann IAT needs an inflection point in the curve, so it is only available with a curve fit of the 3rd degree or higher.
Setting the threshold manually
Want to position a threshold yourself? Drag the threshold line on the lactate curve to the point you want. The module then switches to Manual automatically and recalculates the matching lactate and heart rate at that point.
This helps with atypical curves where the automatic methods give no logical result, or when you as an experienced coach have better judgment.
Choosing the curve fit
The threshold values follow from the shape of the curve drawn through your data points. You choose that shape yourself: from a straight line to a 6th degree polynomial. The 3rd degree is the default and works for most tests.
Entering test data
The thresholds are calculated on your own data points. There are three ways to get them into the test:
- Manually in the step table
- Generate steps from a pattern (start value, count, increment and duration), then fill in lactate and heart rate
- Read from a photo or pdf: upload a photo or scan of a protocol sheet and the module reads the steps automatically
There is no direct integration with external test software such as Inscyd. If you have a protocol sheet or printout from another setup, you can scan it and have it read in.
Good to know
- The chosen method is saved per test. You can change it later and recalculate the thresholds at any time.
- Your training zones follow automatically from the thresholds.
- You carry the thresholds and the curve into the lactate test report for your athlete afterwards.