Glossary
Zone 2
The easy band, usually 60-70% of maximum heart rate. It is meant to be the pace at which you can hold a conversation for the whole run.
What it is
The easy end of the effort scale. In a five-zone model it usually means 60 to 70% of your maximum heart rate.
The point of it is volume. Most of the aerobic benefit of running comes from time spent at an effort you can repeat tomorrow. Seiler's work on elite athletes found roughly 80% of their sessions sat at this kind of easy effort.
What it is not
It is not a magic intensity, and it is not a rule you are failing at. The common complaint is real: _my easy-run heart rate is 160 and I cannot stay in zone 2_. Four things cause that, in this order of likelihood.
- Your maximum is set from a formula and is too low for you.
- The run is on a hot day, or you are tired, or the route climbs.
- Your watch is reading your cadence rather than your pulse.
- You are running too fast.
Only the fourth is a fitness problem, and it is the one people assume first.
| What you see | Likely cause | What to check |
|---|---|---|
| Zone 4 on every easy run | max set too low | your highest ever reading |
| Heart rate equals cadence | wrist sensor lock | wear a chest strap once |
| Fine in winter, high in July | heat | compare same route, cooler day |
| Falls after 3 weeks easy | it was pace | keep going |
What moves it
- The maximum your zones are built on. The biggest lever by far.
- Heat. Expect 5 to 10 bpm more at 30 °C (86 °F) than at 15 °C (59 °F).
- Sleep and illness. Both lift heart rate at a fixed pace.
- Hills. Even a gentle climb pushes you a zone up.
When to ignore it
Ignore it if the talk test says otherwise. Speaking in whole sentences is the better signal, and it needs no calibration.
Ignore it in the first two weeks of running. Early on, almost nothing lands in zone 2, and walking breaks are the fix rather than a failure.
Sources
- Seiler S, Kjerland GO. Quantifying training intensity distribution in elite endurance athletes. Scand J Med Sci Sports 16(1):49-56, 2006 primary
- Persinger R et al. Consistency of the talk test for exercise prescription. Med Sci Sports Exerc 36(9):1632-1636, 2004 primary
- Stoggl T, Sperlich B. Polarized training has greater impact on key endurance variables. Front Physiol 5:33, 2014 primary