# Zone 2

Zone 2 is steady, conversational aerobic exercise at roughly 60–70% of maximum heart rate.

It builds aerobic fitness with little fatigue and makes up most of the training of many endurance athletes. The talk test is a practical check: full sentences, but you would not choose to sing.

Also called: Zone 2 training.

Related: [Heart rate reserve](https://revns.com/dictionary/heart-rate-reserve.md), [VO2 max](https://revns.com/dictionary/vo2-max.md), [Polarised training](https://revns.com/dictionary/polarised-training.md)

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Canonical: https://revns.com/dictionary/zone-2
Index of everything: https://revns.com/llms.txt
revns gives training guidance, not medical advice.