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Why is my heart rate so high while running?

Why is my Heart Rate so high while running?

This question crops up all the time! You are out for an easy run, but when you get home and check the heart rate data from your sports watch, it looks very high. How can this be? Am I ill? Do I need to see a doctor? Why is my heart rate so high while running? Or more specifically, why is my heart rate high on easy runs? How is it possible for my heart rate to be that high when it seemed like I was going for a really slow run with low effort?

For example, at an easy, conversational pace, you’d expect the average forty year old runner’s heart rate to be around 140-150bpm (beats per minute). At this effort level, you’d be able to “say a sentence of about this length without having to gasp for breath in the middle”. But when you look at the data, it says 170-180-190 heart rate when running, and you’d have to walk to get in Zone 2! That’s a high BPM when running, no matter how good you are, and would be more appropriate to a Zone 5, max effort 5K or interval session! Weird right? If you have a high heart rate when running but feel fine, this guide may solve it for you.

Firstly, let’s state that if the data is correct, and your heart rate really is very high while running at an easy effort, you should definitely get yourself checked out out by a doctor. Perhaps your brain can’t regulate your heart rate properly, leading to Tachycardia Arrhythmia. It’s rare, but possible.

However, before you get too excited and rush to get an appointment at the clinic, do a few sanity checks on the data next and understand how easy it is for the data to be completely wrong!

After you’ve read the below solutions to having a high hr when running, you should check out our course on improving your running form (link opens in new tab) so that you can be faster and more relaxed on your runs.

Is it hot where you are running?

More people search for this high hr issue during the summer than the winter (according to analytics that hit this article). If it’s hot, your heart rate will rise a lot higher and quicker than in cool weather. If this might be what is affecting you, I’ve written a whole article about running in the heat.

However, read on to learn about another issue that affects heart rate readings:

Look at the heart rate graph more closely!

Exhibit A:

Why is my heart rate so high while running?

Does your heart rate look like Exhibit A above most times you run? Does it shoot up at the beginning and stay high the whole way?

Exhibit B:

Heart rate rises gradually throughout the run

Or does it look like the Exhibit B above, where the heart rate rises gradually throughout the run?

Exhibit C:

very high heart rate when running slowly

Or perhaps it jumps around erratically like in Exhibit C above, suddenly going from a low heart rate to a high heart rate (see the “shelf” around 22 minutes to 27 minutes), even though you were maintaining the same pace throughout?

Assuming you are running at the same pace throughout the run, you’d expect to see something like Exhibit B. So why are you seeing something different?

Problems normally caused by optical wrist-based heart rate monitors

Most of the problems I see in this area stem from people using the optical heart rate monitor on their sports watch without setting the watch up correctly.

There is a sensor inside the watch with strong LED lights either side of it. The sensor looks at changes in the reflected light level caused by the blood pulsing past it. For this to work properly, the watch needs to be set up correctly on the arm. If it’s not, it can start measuring your cadence instead!

Cadence monitor instead of Heart Rate monitor!

What happens to your wrist when you run? Your arm is counter-balancing the movement of your legs and thus your wrists are moving forwards and backwards at the same rate as your feet are taking steps. The number of steps you take each minute is called Cadence. This normally doesn’t change much throughout your run.

When you are using a wrist based heart rate monitor instead of a chest strap sensor, the watch needs to be snug against your wrist, otherwise slight movements in the watch position caused by the arm movements are determined to be changes in light levels. Since that’s exactly what the sensor in the watch is looking for, it can easily lock on to these instead. Thus it’s sometimes called “Cadence Lock”. In this case, the graph will look just like Exhibit A above. Or if perhaps it will get confused and jump between the two, like in Exhibit C, with a few minutes showing real heart rate and few minutes showing cadence instead. Note that I’ve included the cadence readout in Exhibit C and you can see it exactly matches the false heart rate value.

How to get a more accurate reading from an optical heart rate monitor.

Here are your options to fix this.

First, try tightening the strap. If you can quickly and easily slide your finger under the strap, it’s too loose. Tighten it until your finger gets a bit stuck when trying to slide under the strap. This will mostly likely fix the issue.

If the strap is already tight, but you are still measuring your cadence, or getting erratic readings, try shoving the watch up your arm a bit towards the elbow. This will move it on to a thicker bit of flesh, with more blood flow and a snugger fit.

Another option is to switch the watch to the other arm. Most people are right handed, but wear their watch on the left. However their left wrist will be slightly thinner due to less strength from the hand bias. See if your other wrist gives a more reliable reading.

Oddly, if your strap is too tight, it will prevent your blood flow from being measured properly and might measure too low, for example during a hill session, you’d expect it to be really high, but it’s not reacting and is staying low, so it appears your heart rate is low while running fast.

Finally, if you still can’t get a reading that looks right, apart from seeing a doctor, you could try a chest strap sensor instead. Most decent sports watches will support one. They need to be wet to work well, so soak the strap before you leave, but they are generally accepted to give a good reading, especially at the high effort levels required in 5K races, interval sessions or Maximum Heart Rate Stress Tests that help you determine your heart rate training zones.

I hope you found that useful. If it has helped you answer the question why you have a high heart rate during exercise but not out of breath, or why is my heart rate so high while running, please comment below. If you are wondering what a healthy running heart rate is, click that link.


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Your Coach, Charles Rodmell:

Online Running Coach

"Everyone can improve their running, but only if you know how. Here you'll find all the resources you need, from free in-depth running articles to bespoke running coaching. Let us know how you get on and tell all your friends!"

8 thoughts on “Why is my Heart Rate so high while running?”

  1. Thanks for this note. I am here because my hight heart rate shown by my smartwatch during my runs… I am 56 y.o. which max h.r. should be 220-56=164 b.pm. but as per my smart watch my average heart rate is 185b.p.m (running 5k) with max’s at 197, 200 and one time it was 210 which it could not be possible… I do not feel any pain or disconfort or breathing problems… I was never concern about that since I started running as a 16 y.o. but since I got my smartwatch five month ago start to see this. I will get a chest strap sensor for peace of mind.. thanks.

    1. Great Dann. And if you use the search function on this site for “maxhr”, you’ll find a test you can do to find how high it can actually go (the 220 – age thing is often very wrong).

  2. So in a nut shell it’s a problem with my brain or a problem with my heart rate monitor. Those are the two answers. I better see the doctor.

  3. Thanks Charles for explaining one of the most sought after topic for runners. You have detailed it quite wonderfully all the possible scenarios to be observed on high heart rate. I am on it and fongers crossed hope it works for me.

    Cheers

  4. thank you for explaining why it was so painfully slow (literally) to run when keeping my heart rate in the proper zone. hopefully the easy fix works on my next easy day.

  5. I was wondering why I have such a high heart rate when running and it was that easy. I tightened the watch a notch and my heart rate dropped down to a sensible level. I think the cold weather might have made my hands and arms cold, so the watch was moving around a bit when I ran. Thanks.

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