Marathon heart rate: what heart rate should you run a marathon at?

Everyone wants one number for marathon heart rate. Type it into the watch, hold it for 26.2 miles, collect your medal. Sadly, your heart didn't read the plan.

Short answer: for most recreational runners, marathon effort starts around zone 3 (70–80% of max heart rate) and creeps upward from there, even at an even pace. On race day it often reads higher than the textbook range, and late in the race it stops telling you much about effort. So the useful heart rate for running a marathon is a cap for the first half, not a target for the whole race. This post covers the marathon heart rate zone, why it drifts, how to find your own numbers, and how to use them on race day, whether you work it out yourself or use an app that schedules hard runs away from leg day.

What heart rate should you run a marathon at?

Start with your zones. If you don't know them, plug your age or max heart rate into this zone 2 calculator, or do the arithmetic below. This is the same five-zone model used across the whole blog, so the numbers match everywhere; if you want the full picture of what each band is for, start with heart rate zones.

The convention many coaches use is a marathon heart rate zone somewhere between 65% and 80% of max. That's the range named in a 2022 study by Billat and colleagues, which then measured what actually happened when ten recreational men ran a marathon wearing a portable gas analyzer. After the first 5 km, their heart rate sat between 88% and 91% of max for the rest of the race (Billat et al., 2022). That's upper zone 4 on our scale, well above the convention.

Ten runners is a small group, so don't treat 88–91% as your target. Treat it as a warning: race-day heart rate is often higher than people expect, and the textbook range is a planning tool, not a prediction.

Marathon runner heart rate: why one number doesn't work

Three things make a single marathon runner heart rate unreliable.

1. It drifts upward

During long exercise, heart rate creeps up while the amount of blood pumped per beat falls. That's cardiovascular drift, and it typically shows up after 10–20 minutes of exercise (Coyle and González-Alonso, 2001). Heat and dehydration make it bigger.

In a marathon you see it plainly. In eleven recreational men running a flat road marathon (mean finish 3:10:22), heart rate rose significantly from the start of the race to the end, even though their kilometer splits got slower (Gronwald et al., 2021). Slower pace, higher heart rate. If you hold a fixed heart rate cap all race, you'll be forced to slow down more and more as drift builds, whether you need to or not.

2. It stops tracking effort late in the race

In the Billat study above, heart rate held steady as a percentage of max, but oxygen uptake fell from 81% to 74% of max and pace fell further. The ratio between heart rate and oxygen use climbed between km 5 and km 42. The authors' conclusion was blunt: pacing a marathon by heart rate zones isn't recommended, and learning to pace by perceived exertion (RPE) is the better option (Billat et al., 2022).

A second study from the same group, with continuous gas measurements during an actual marathon, found heart rate and breathing rate rose progressively in every runner, and concluded that a marathon should be self-paced with RPE (Billat et al., 2022).

3. Your max heart rate is probably a guess

Every percentage above depends on a max you may never have measured. Age formulas are population averages. In 180 recreational marathon runners, the common 220 − age and Tanaka formulas overestimated measured max by about 5 beats per minute in women, while 220 − age underestimated it by about 3 beats in men (Nikolaidis, Rosemann and Knechtle, 2018). Individual errors are bigger than the averages. Your running hr zone from an age formula is a starting point, not a measurement.

How to find your own marathon heart rate

The best marathon heart rate is the one you've seen in training at your goal pace. Here's how to collect it.

1. ›Get your zones roughly right first. Use a recent race max or a threshold test if you have one; an age formula if you don't.
2. ›Run marathon-pace segments inside long runs. Later in the build, finish some long runs with several miles at goal pace, in conditions similar to race day.
3. ›Note the heart rate in the first 15–20 minutes of each segment, once it has settled. That's your early-race number.
4. ›Note how much it climbs by the end. That's your drift, and it tells you what's normal for you.
5. ›Check the effort. Goal pace should feel like RPE 5–6 early on: steady, short sentences, nowhere near a tempo run.

If goal pace keeps producing zone 4 numbers in the first few miles of a long run, on cool days, the goal is probably too ambitious for this build. That's useful to know in week 12, not at mile 18.

Worked example: a 40-year-old with an estimated max of 180 (Tanaka, 208 − 0.7 × age) has a zone 3 of roughly 126–144 and a zone 4 of 144–162. If their marathon-pace miles in training settle around 140, that's their early-race cap. Seeing 150 or more late in the race isn't a disaster. It's drift.

Marathon race heart rate zone: how to use it on race day

Heart rate is most useful early, when adrenaline and fresh legs make every pace feel easy. It's least useful late, when drift has changed what the number means.

A few rules that make this work:

• ›Expect race-day numbers to read high early. Nerves and caffeine do that. Run by your training pace and effort for the first mile or two and let heart rate settle.
• ›On hot days, slow down rather than chase pace. Heat pushes heart rate up at the same speed, so a cap that fit in training will arrive sooner.
• ›On hills, run by effort. Heart rate will spike on a climb. Ease off, then settle back.
• ›Don't panic when it climbs. Drift is physiology, not failure. If you feel genuinely unwell, dizzy or have chest pain, stop and get medical help.

Training heart rate for a marathon

Race day is one day. The other 120 or so are where your marathon heart rate gets lower at the same pace.

• ›Most runs in zone 2. Easy, conversational, slower than your ego wants. Our guide to zone 2 running covers pace, walk breaks and why it feels too slow.
• ›Long runs mostly in zone 2, with marathon-pace segments in zone 3 later in the build.
• ›One quality session a week: marathon-pace work in zone 3 or tempo and threshold work in zone 4.
• ›Zone 5 in small doses. Intervals help, but they're a supporting act in a marathon build; our guide to zone 5 training explains why it's used sparingly.

That easy-heavy split isn't laziness. Across descriptive studies of well-trained endurance athletes, about 80% of sessions were done at low intensity and about 20% were dominated by hard work (Seiler, 2010). For why low-intensity work is the base of all of this, including for people who also lift, see the zone 2 guide.

What you're hoping to see over the build: the same marathon pace producing a lower heart rate, or the same heart rate producing a faster pace. That's the aerobic base improving, and it's the only heart rate trend that really matters for your race.

Common marathon heart rate mistakes

• ›Running the whole race to a fixed cap. Drift will force you to slow down for reasons that have nothing to do with fitness.
• ›Trusting a default max. If your watch set your zones from your birthday, your marathon heart rate zone is a guess.
• ›Ignoring heart rate entirely in the first 10K. This is where it's most useful. Going out too fast is the classic marathon mistake.
• ›Training every run in zone 3. Then race pace feels like every other run, and you've built no easy base under it.
• ›Treating a high number late in the race as a stop sign. Unless you feel unwell, it's drift. Run by effort.

How exrsz handles marathon heart rate

exrsz builds a periodized marathon plan from your goal, schedule, level and equipment, with every run given an intensity target in the same five-zone model. It balances easy, marathon-pace and threshold running against your lifting in one plan, adapts each week to how you actually trained, and reshuffles missed sessions so the build still lands on race day.

FAQ

What heart rate should I run a marathon at?

For many recreational runners, marathon effort starts around zone 3, 70–80% of max heart rate, then drifts upward. The best target is the heart rate you saw at goal pace in training, used as a cap for the first half rather than a number to hold all race.

What is a normal marathon runner heart rate during a race?

It varies a lot by person and course. In one small study, recreational men ran most of a marathon at 88–91% of max heart rate, higher than the 65–80% many coaches prescribe (Billat et al., 2022).

Why does my heart rate go up during a marathon if my pace stays the same?

That's cardiovascular drift: during long exercise, heart rate creeps up while the blood pumped per beat falls (Coyle and González-Alonso, 2001). Heat and dehydration make it bigger.

Should I pace a marathon by heart rate or by feel?

Use both, at different times. Heart rate is a useful ceiling in the first 10K; after that, pace and effort are better guides, which is what researchers who measured runners during real marathons recommended (Billat et al., 2022).

What marathon heart rate zone should I train in?

Mostly zone 2 for easy and long runs, zone 3 for marathon-pace work, and zone 4 for tempo sessions, with zone 5 used sparingly.