What are the five heart rate zones?
Heart rate zones split your effort into five bands, each set as a percentage of your maximum heart rate. Each band trains something different, so knowing which one you are in tells you what a session is actually doing.
| Zone | % of max HR | What it builds |
|---|---|---|
| Zone 1 | 68–73% | Recovery and warm-ups. Light enough to help you bounce back from hard days. |
| Zone 2 | 73–80% | Your aerobic base. More mitochondria, better use of fat as fuel, a bigger engine. |
| Zone 3 | 80–87% | Aerobic fitness under a bit more pressure. Steady, honest work. |
| Zone 4 | 87–93% | Threshold. Raises the pace you can hold before you tie up. |
| Zone 5 | 93–100% | VO2 max and top-end speed. Short, hard, and only with full recovery between. |
Low zones build the engine: endurance, recovery and the ability to keep going. High zones build the top end. Most people sit in the middle by accident and get a bit of both and not much of either. Zones stop that.
How do I find my max heart rate?
The quick estimate is 220 minus your age. It is a starting point, not a measurement: for any one person it can be ten beats or more out either way. A race or a hard hill effort with a chest strap gets you closer. Every watch and app calculates zones slightly differently, so pick one method and stick with it.
Worked example. A 40-year-old: 220 minus 40 is 180 bpm max. Zone 2 is 73 to 80% of 180, so 131 to 144 bpm. That is the range for most of their weekly running. The heart rate zone calculator works yours out in seconds.
Re-check every few months, and remember heart rate lags effort by a minute or two: on short reps, go by feel.
How much Zone 2 training should I do?
A strong aerobic base decides more race results than anything else. Easy, steady work grows the small blood vessels around your muscles, adds mitochondria and teaches your body to burn more fat at a given pace, which saves carbohydrate for when the race gets hard. Once built, it fades slowly.
- 3 to 4 sessions a week in Zones 2 to 3.
- 40 to 60 minutes each: long enough to matter, short enough to recover from.
- 4 to 8 weeks until most people feel the difference in endurance and recovery.
The common mistake is letting easy runs creep into Zones 3 and 4 because Zone 2 feels too slow. If you have to walk the hills to stay in zone, walk the hills. It gets quicker.
What sessions train Zones 4 and 5?
One or two a week is plenty alongside your base work. Warm up and cool down every time with 10 to 15 minutes of light jogging and some dynamic drills.
| Purpose | Session |
|---|---|
| VO2 max | 2 min in Zone 4, jog or walk 1 min. 2 min in Zone 5, jog or walk 2 min. Repeat the pair 4 to 5 times. |
| Top-end speed | 30 s sprint, the fastest pace you can hold for the whole 30 seconds. Jog or walk 1 min. Repeat 8 to 10 times. |
On a 30-second sprint your heart rate will not reach Zone 5 before it ends; go by effort. The guide includes an example week, and you can build your own with the week planner.