What it is
An easy run is any run performed at a genuinely comfortable, conversational pace — typically 65–75% of maximum heart rate. It is the backbone of marathon training and should make up 70–80% of total weekly volume.
"Easy" means easy. If you can't hold a full conversation without pausing to breathe, you're running too fast.
How to run it
- —Pace: Roughly 60–90 seconds per kilometre slower than marathon goal pace. If in doubt, slower is always correct.
- —Heart rate: Zone 2 — typically 130–145 bpm for most trained runners. Find your ceiling and stay under it.
- —Feel: You should finish feeling like you could have run further. Slight residual fatigue is fine; feeling spent is not.
- —Duration: Anywhere from 30 minutes to 90+ minutes depending on where it sits in the week.
The adaptation
Easy running triggers the primary aerobic adaptations without the recovery cost of harder sessions:
- —Mitochondrial density — more mitochondria per muscle cell means more aerobic energy per stride.
- —Capillarisation — new capillary beds improve oxygen and fuel delivery to working muscles.
- —Fat oxidation — sustained low-intensity running upregulates the fat-burning pathway, protecting glycogen for race-pace efforts.
- —Cardiac stroke volume — the heart adapts to pump more blood per beat, lowering resting heart rate over months.
These adaptations are slow — they accumulate over weeks and months, not sessions. The easy run is the compound interest of marathon training.
When to use it
- —Every day that isn't occupied by a key session (threshold, intervals, long run).
- —The day after a hard session — a 30–45 minute easy run actively aids recovery better than full rest in most cases.
- —When life stress is high, energy is low, or sleep was poor. Convert any session to easy pace rather than skipping entirely.
When not to use it
- —When you're genuinely injured and running would worsen the injury.
- —As a disguised moderate run — running at "comfortable but honest" feels virtuous but isn't easy. The middle zone is where most amateur runners accumulate junk mileage that blocks adaptation without driving it.