Lactate Threshold: The Running Metric That Changes Everything
Your lactate threshold is the pace where your body can no longer clear lactic acid fast enough. Training around it is one of the most effective ways to get faster.
Day 25: Lactate Threshold
Your lactate threshold (LT) is the intensity at which lactic acid starts to accumulate faster than your body can clear it. Exceed it, and your muscles fatigue rapidly. Stay below it, and you can sustain effort almost indefinitely.
Three ways Garmin shows your LT
- Pace: The pace (per km/mile) you can sustain at threshold
- BPM: Your heart rate at threshold (e.g., 162 BPM)
- Watts: Power output at threshold (for cyclists)
How to find it on your Garmin
Garmin Connect → Performance → Lactate Threshold. You need several outdoor runs with heart rate data for Garmin to estimate it automatically.
For a manual test: run at a comfortably hard effort (you can speak in short sentences but wouldn't want to) for 30 minutes. Your average heart rate in the final 20 minutes ≈ your lactate threshold heart rate.
How to train around it
- Easy runs (80% of your training): 15–30 BPM below LT heart rate
- Tempo runs (10–15% of training): Right at LT — sustained 20–40 minute efforts
- Intervals (5–10%): Above LT — short hard reps with recovery
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