If you take one idea from this article, make it this: most runners run their easy days too hard and their hard days too easy. Training zones fix that by giving each run a clear job.
The five zones
Coaches slice the intensity spectrum into zones. The exact boundaries vary, but the intent is consistent:
- Zone 1–2 — Easy / recovery. Conversational. You could talk in full sentences. This is where the majority of your weekly volume should live.
- Zone 3 — Steady / tempo. Comfortably hard. Sustainable for a long time but you wouldn't want to chat.
- Zone 4 — Threshold. The pace you could hold for about an hour all-out. The classic "comfortably uncomfortable" effort.
- Zone 5 — Interval / VO₂max. Hard, repeatable efforts of a few minutes with recovery between. This is where top-end speed is built.
Why easy has to be easy
The aerobic system — capillaries, mitochondria, fat metabolism — adapts best to a lot of easy running. If every run is moderately hard, you get the worst of both worlds: too tired to nail the hard sessions, too fast to maximise aerobic adaptation. Slowing your easy runs down is, counterintuitively, how you get faster.
Finding your zones
You can estimate zones from a recent race or time trial. Our free race pace calculator turns a goal time into target paces, and the race time predictor estimates your current fitness from one result. In the RUNNIQ app, the analyst sets your zones automatically from your recent runs and keeps them current as you improve.
Putting it together in a week
A balanced week for most runners is roughly 80% easy and 20% hard. A typical intermediate plan might pair one interval session and one tempo run with two or three easy runs and a long run — every run in its proper zone, nothing in the mushy middle.
Train each zone for its purpose and the paces take care of themselves.