What the slope of the lactate curve describes
The slope shows how strongly blood lactate rises as workload increases. A flatter curve can reflect effective clearance or substantial production only at higher intensities; a steeper curve means a smaller workload increase produces a larger lactate rise.
Production and clearance shape the curve
The source relates slope to glycolytic capacity, which contributes to lactate production, and oxidative capacity, which supports its use and clearance. Well-trained endurance athletes often have flatter curves, but the absolute threshold still matters.
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Changes in the entire curve may be more informative than one threshold value. The German article discusses a flatter curve alongside improved oxidative capacity and a steeper curve alongside possible fatigue, overtraining or weight change.
- A flatter curve: an aerobic-efficiency signal to interpret in context
- A steeper curve: check fatigue and recovery rather than infer one cause
- A shift to the right: higher absolute performance
- A shift to the left despite training: consider recovery or illness
Use shape together with LT1 and LT2
Progress tracking should compare both thresholds and the whole curve. The article contrasts athletes with different LT2 values and different slopes to show why a single threshold number does not capture the entire response.