Lactate slope: what a steep curve says about training

Why this matters

Curve shape can be more informative than a single threshold value, especially when you compare tests over time.

What to record

For every useful lactate analysis, intensity and lactate must be linked clearly. Record pace or watts, mmol/L value, heart rate if available and the stage duration.

• Pace or watts for each stage
• Lactate in mmol/L
• Optional heart rate and RPE
• Test conditions such as heat, altitude, sleep and nutrition

How to interpret it

Look at the curve, not only at one value. LT1, LT2, VLamax and zones become more reliable when the protocol is repeatable and the curve shape is plausible.

• A flatter curve often signals better aerobic capacity
• A steep rise can indicate high glycolytic contribution
• Outliers must be checked before interpretation
• Compare slopes only under similar conditions

Practical next step

Use the same protocol for future tests and compare trends instead of overinterpreting one isolated result.