First and second thresholds (VT1 and VT2) explained
The two ventilatory thresholds split intensity into three domains. What they mean, how to feel them and how to use them in training.
Besides the lactate threshold everyone talks about, there's an earlier threshold. Together they split intensity into three zones that explain almost all endurance training.
First threshold (VT1)
The point where breathing starts to speed up. Below it you can talk normally and keep going for hours. It's the upper limit of easy runs and base training.
Second threshold (VT2)
The point where breathing becomes clearly laboured and you can no longer hold a conversation. It roughly matches lactate threshold or FTP.
The three domains
- Below VT1: easy. Most of your volume goes here.
- Between VT1 and VT2: moderate. Tempo and marathon pace.
- Above VT2: hard. High threshold intervals and VO2max.
The talk test
Without a lab, talking is a good guide: if you can say long sentences, you're below VT1; if only single words come out, you're above VT2.
Pushing VT1 towards faster paces is, to a large extent, what aerobic base training achieves.