RPE vs heart rate: should you run by how it feels, or by the number on your watch? We get this question a lot, usually from runners who trained with heart rate zones for years and then started racing on trails. Both are ways to read effort. On flat, steady ground they tell you roughly the same thing. Put a steep climb, a technical descent or a hot afternoon in front of you, and they start to disagree.
We coach effort. Every session in a Vert plan is set by RPE (how hard it feels, from 1 to 10) and time. Heart rate still has a place, as a check, not the boss. Here’s when we trust each one, and how to use both without getting fooled by either.
Training by effort?
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The quick answer: RPE vs heart rate
For trail running, use RPE (rate of perceived exertion) as your main guide and heart rate as a second opinion.
- RPE responds instantly and includes everything your body feels: the climb, the technical descent, the heat, a bad night of sleep.
- Heart rate is objective, but it lags behind changes in effort and drifts with heat, fatigue, altitude and caffeine.
- Use heart rate to keep easy days honest and to spot fatigue trends over weeks.
- Use RPE on climbs, descents, technical terrain and on race day.
New to the scale? Start with our guide to RPE in trail running.
Why heart rate misleads on trails
Pace stops working the moment the trail tilts. Our trail running pace calculator shows how much climbing slows you down. Heart rate looks like the fix, but it has its own blind spots.
Climbs: heart rate lags behind your effort
When you hit a steep climb, your effort jumps right away. Your heart rate takes a minute or two to catch up. On a short, punchy climb you can reach the top before your watch shows how hard you worked. Go by heart rate and you’ll push too hard in the first minutes of every climb. Go by RPE and you settle into a sustainable effort from the first step.
Descents: low heart rate, high cost
Running downhill drops your heart rate, but your legs are working hard to absorb the impact. A long descent at an easy heart rate can leave your quads more beaten up than a hard climb. Heart rate can’t see that cost. RPE, and your legs, can.
Heat, altitude and fatigue push heart rate up
On a hot day, at altitude, or late in a long run, your heart rate rises at the same effort. This is called cardiac drift. If you hold a fixed heart rate zone, you slow down more and more as the run goes on. Sometimes that’s the right call. Often you’re just chasing a number that no longer means what it did at the start.
Bad days and wrist sensors
Caffeine, stress, poor sleep and illness all shift your heart rate. Wrist sensors can also be off, especially on rough terrain or in the cold. A chest strap is more accurate, but it still measures your heart, not what the terrain is asking of you.
Where heart rate is still useful
- Keeping easy runs easy. Most runners run their easy days too hard, and our coaches see it every week. A heart rate ceiling on flat or rolling easy runs is a good check that you’re really at RPE 4 to 5, which is zone 2 on your watch.
- Steady efforts on even ground. On a flat loop or a long, even climb, heart rate and effort line up well, which makes it a good place to calibrate.
- Spotting fatigue over time. If the same easy run costs a much higher heart rate for days in a row, or your resting heart rate stays higher than usual, you may not be recovering. Take it easy and tell your coach.
Vert Pro • Vert Coaching: built and reviewed by expert trail coaches.
Every session in your plan is set by effort and time.
Your plan is built around your race and the terrain you train on. A Vert coach reviews it, and it adapts as you progress. Workouts sync to your Garmin, Coros or Suunto.
RPE vs heart rate zones: how we convert them
This is the conversion we use when you export a Vert session to your watch with heart rate. Your watch applies it to the heart rate zones you’ve set on it, so the beats per minute are yours.
| RPE | How it feels | Typical sessions | Heart rate zone |
|---|---|---|---|
| 1 to 3 | Very easy, you could chat all day | Warm-ups, cool-downs, recovery | Zone 1 |
| 4 to 5 | Comfortable, full conversation | Easy runs, long runs | Zone 2 |
| 6 | Steady, short sentences | Steady runs, race effort on a short trail race | Zone 3 |
| 7 to 8 | Hard but controlled, a few words at a time | Threshold work, tempo runs, hill intervals | Zone 4 |
| 9 to 10 | Very hard to all out, you can’t talk | Short, hard intervals, used sparingly | Zone 5 |
The RPE ranges and sessions are the ones we use in Vert plans. If your zones feel off, check them on your watch first: the conversion is only as good as the zones it maps to.
How to calibrate RPE with your heart rate
- Start on flat ground. On your next easy run, settle at a conversational effort (RPE 4 to 5) and note your heart rate after 15 to 20 minutes. It should sit in zone 2. That’s your easy-day reference.
- Watch a climb. On a steady climb, hold the same effort and see how long your heart rate takes to rise. That delay is why you lead with RPE on hills.
- Check late in long runs. Compare your heart rate in the last hour with the first hour at the same effort. The gap is your drift.
- Keep notes for a few weeks. You’ll soon know when your heart rate is telling you something useful, and when it’s just noise.
How Vert plans use effort
Years ago we could have built our plans around pace and distance, like most running apps. We chose effort, and we’ve stuck with it. Every session in a Vert plan is set by RPE and time, because on a trail the terrain decides your pace, so we coach the effort. Each week your plan also gives you a Mountain Index target, the metres of climbing per kilometre that match your race.
Prefer training by heart rate?
You can. Export your Vert sessions to your watch with heart rate and each step shows up as a heart rate zone instead of an RPE, using the zones you’ve set on your watch: RPE 1 to 3 becomes zone 1, 4 to 5 zone 2, 6 zone 3, 7 to 8 zone 4 and 9 to 10 zone 5. Your watch syncs with the app (Garmin, Suunto and COROS). Just don’t let the number override what your body and the terrain are telling you, especially on climbs.
Race day: effort first
Race day is where heart rate fools runners most. Excitement, heat, altitude and the first climb all push it up. Chase a zone and you’ll either back off for no reason, or miss that you’re working too hard on a climb because your heart hasn’t caught up yet.
So race by effort, and match it to how long you’ll be out there:
- A short trail race, like a 20 km: you can sit around RPE 6 to 7, working but controlled, and push the last climbs if you have something left.
- A 50k: mostly RPE 4 to 5, with some climbs at 6. Going out at 6 or 7 in the first hours is one of the most common reasons runners struggle at the end.
- An ultra, like an 80 km: most of the day should feel like RPE 3 to 4, as easy as your easy runs or easier. Climbs will push it up for a while; bring it back down at the top. If it feels like a 6 in the first hours, you’re going too hard, whatever your watch says.
The longer the race, the lower your effort. Use heart rate as a guardrail, not a target.
RPE vs heart rate: FAQ
Is RPE better than heart rate for trail running?
For most trail running, yes, as your main guide. RPE reacts instantly to climbs, descents and technical terrain, while heart rate lags and drifts with heat, altitude and fatigue. Heart rate is still useful as a check on easy days and for spotting fatigue.
What heart rate zone is RPE 5?
Zone 2. When you export a Vert session to your watch with heart rate, RPE 4 to 5 becomes zone 2, based on the heart rate zones set on your watch. It’s easy, conversational running.
Why is my heart rate so high on climbs?
Climbing is hard work, and heart rate keeps rising for a minute or two after your effort changes. Heat, altitude and fatigue push it higher still. Settle your effort by RPE and let your heart rate catch up.
Should I use heart rate on race day?
Use it as a guardrail, not a target. Race-day heart rate runs high with excitement, heat and altitude. Most trail runners pace better by effort, with heart rate as a check.
Can I train by heart rate with Vert?
Yes. Export your sessions to your watch with heart rate and each step appears as a heart rate zone, using the zones set on your watch: RPE 4 to 5 becomes zone 2, RPE 6 zone 3, and so on.
Can I use RPE and heart rate together?
Yes. Lead with RPE, especially on hills and technical terrain, and use heart rate to keep easy days easy and to spot fatigue trends over weeks.
Vert Pro • Vert Coaching: a plan built for your race and your level.
The trail decides your pace. Your plan coaches the effort.
A trail plan built by coaches around your race, the time you have and the terrain you train on.
