QUICK ANSWERS
Zone 2 vs HIIT
Easy aerobic training or hard intervals? Most people do best with both, in the right mix
| Zone 2 | HIIT | |
|---|---|---|
| Effort | Easy: you can hold a conversation | Hard: only a few words |
| Heart rate | About 60 to 70% of max | About 80 to 95% of max |
| Session | 30 to 90 min, steady | 10 to 30 min, in intervals |
| How often | Most days | 2 or 3 times a week |
What zone 2 means
Zone 2 comes from five-zone heart rate charts, where it’s the second-easiest zone. Charts differ, so zone 2 isn’t one exact number: on a percent-of-maximum chart it’s about 60 to 70%. A simple test is whether you can talk in full sentences.
What the research found
Key study
Polarized training improved endurance most
- Randomized trial
- 48 well-trained athletes
- 9 weeks
Athletes who did about 70% of their sessions easy and about a quarter as hard intervals, with little in between, improved VO2peak and endurance more than those who trained mostly at threshold, mostly with intervals, or mostly with high volume.
Source 1A balanced week
- 2 interval sessions, such as a 4×4 and a 30/30.
- 2 or 3 easy sessions of 30 to 60 minutes in zone 2.
- 2 days of strength training 2.
Find your own zones with the heart rate zone calculator.
Sources
- Stöggl T, Sperlich B. Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training. Front Physiol. 2014;5:33. doi.org/10.3389/fphys.2014.00033
- Bull FC, Al-Ansari SS, Biddle S, et al. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Br J Sports Med. 2020;54(24):1451-1462. doi.org/10.1136/bjsports-2020-102955
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