High Heart Rate Spikes using Polar H9

Hi all,

Keen to understand from others if this is likely to be a problem with me or my heart rate monitor. Have a Polar H9 that’s performed faultlessly since I bought it in Apr 2023.

I completed this ride on Saturday. My heart rate was a bit higher than normal throughout the ride and it definitely felt very hard, I would have struggled to do one more 3m below/above threshold interval.

After completing the final set I noticed my HRM spike to around 229bpm for about 60s, then again for 30s and finally for 20s. I felt absolutely knackered after the last set of intervals but 225bpm for that length of time seems unrealistic. My maximum HR I’ve ever recorded was 205bpm at the end of a 5k Parkrun where I set my PB - on that occasion I was starting to black out as I crossed the finish line.

So 225bpm seems unrealistic but has got me worried given how long it was picked up for by the HRM.

I did another endurance ride (1 hour) yesterday and the heart rate plot was as I’d normally expect it to be throughout.

Anyone else seen this at all?

Thanks in advance for all replies.

That’s weirldly consistently high if you get my jist, whenever I’ve had interference with a HRM causing high readings its only been for a second. With my Polar H10 (Aug 22) I’ve never seen a spike, in fact the opposite (a low reading) if I need to wipe down the strap a bit.

1 Like

A friend had a similar issue on and off, then one day it spiked and wouldn’t come down. He spent 24 hours in the ER and they had to hit him with the paddles to get it out of arrhythmia. Had an ablation and has been fine ever since.

Ive also had a similar issue, but it was happening mostly when I was trying to lose weight through calorie restriction / carb reduction. I had pretty high cortisol levels, and getting weird arrhythmia symptoms pretty often. Went to a cardiologist and everything looked fine however. Once I upped my carbs and calories in general, it completely went away.

It could also be an abnormal reading from the strap, but worth paying attention to.

1 Like

Pending no health issues, change the battery and see if it continues.

1 Like

Hey @kashcroft!

I checked the ride log data and the HRM connectivity looks solid, however, you may want to change the batteries as @fljones3 mentioned if you haven’t done so since Apr 2023. It’s been a bit!

Additionally, you can check for Firmware Updates:

Let’s make sure your Polar H9 has the latest firmware updates. Often times these updates have various fixes that keep your device running smoothly. You can find directions on ensuring your firmware is up-to-date here: Polar H9 Firmware Updates.

Now, if you are really worried I would consider contacting your doctor and getting examined just in case! Better be safe than sorry :slight_smile:


Thank you everyone. Just downloaded the Polar App and it did a firmware update. Says the battery is half full so will change as a precaution.

My wife has also got a watch with a HRM she is going to lend me. Guess if it does happen again then if they both pick it up I probably need to go get checked out.

I think this is probably a good result of us wearing heart rate monitors a lot more than non-athletes! Hopefully nothing to worry about anyway.

1 Like

About a year ago, I was seeing strange spikes with my H10. My doctor had me do a stress test to be sure. Ultimately, it turned out to be the strap for the H10 was failing. I got about 2 years out of it. With a new strap, everything was back to normal.