Running with Polar HRM - M400: Hi, I went for... - AF Association

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Running with Polar HRM - M400



I went for a run last week intending to keep my HR low for approx 5 mins before increasing to approx 70-80% max HR, followed by a 5 min warm down

From the attached graph you can see my HR jumped up into the 150's with no change in effort before 5 mins. I didn't feel any change in myself

I carried on at a similar pace and just after 30 mins walked to finish (see blue line show pace drop off). During the walk the HR didn't come down but showed more erratic reading until all of a sudden it dropped back to the mid 90s in a similar fashion to how it spiked to the 150's at the start

Any other runners out there experience this. I'm not sure if its genuinely me or it's the Polar HR monitor not coping with my heart doing unusual things once i start running.

I think i have been in NSR since a cardioversion 12 months ago, although i do get the odd twinge that tells me that my heart isn't as it used to be

I have a doctors appt this week, so i am going to ask if i can be referred for some kind of stress tests

11 Replies

I can't comment and I'm not a runner, but my Polar HRM which I use for cycling can't cope with my arrhythmia. When I get an arrhythmia it will jump up to a high figure, stick around there for a while, then suddenly drop back to normal. But my heart didn't really go that high.

I spoke to Polar about it and they said the figures on my model are not averaged at all, so the reading are pretty immediate.


jondeanp in reply to Hidden

Thanks Koll. Do you get arrhythmia's often or occasionally when cycling?

Hidden in reply to jondeanp

No, not usually. More often just when walking around or doing nothing. But just like your graph, my HR will apparently suddenly just drop down, but in reality it didn't drop quickly like that at all.

I wear a Polar FT4 on a daily basis, and mine seems able to cope with high heart rates. The highest I've ever been has been 234bpm. When I use my AliveCor it gives the same reading as my FT4 so I'm quite happy with mine. I don't run but I do a lot of fast walking, around 4-4.5mph.

I'm a runner and use a Garmin Heart Rate monitor. I'm no expert, but I do obsessively monitor my stats. The chest straps on the Garmin are notoriously bad and often spike to high heart rates for the first 5 or 10 minutes of a run. Nylon t-shirts can cause problems and hitching up the strap causes spikes. I'm using a Polar chest strap now which is much better, but myself and friends still get the occasional spikes. The increase to 157 BPM looks totally normal, it always takes a few minutes for your heart rate to speed up when running. 157 BPM for me would mean I was working fairly hard, but we all have different max heart rates depending on genetics and age. I see you have a few odd spikes up into the 170's which I'd have thought could be you running up a hill, hitching up the chest strap, a "glitch" or some heart event.

The high heart rate while you were walking at the end seem strange, were you on the flat? I'd recommend you borrow someone elses monitor just to make sure your unit isn't dodgy. I'd also recommend getting some ultra sound gel and put a bit on your HR strap before setting off running, costs £4 or £5 from amazon

Thanks guys.

It is a new device but i have used Polar products before, however i have not been able to see my efforts in graph form previously, only real time whilst running.

One of the strange things Ive experienced also on a previous run was during a period of prolonged reasonable effort my HR actually started dropping (according to the monitor). This was a little disconcerting and i made sure i dropped to walking pace until it recovered

Since my AF & cardioversion i am only just starting to get back into it, but a little worried whether there may be things going on that mean i really shouldn't be running.

I don't want to keel over just yet. This damn AF... (annoyed)


I have a Polar RS400 that has registered 235 BPM when I'm in atrial fibrillation / atrial flutter caused by vigorous exercise and, I've seen the same reading from an ECG machine when I've been in atrial fibrillation / atrial flutter during a Bruce Protocol treadmill stress test; so I'm pretty sure that Polar HRMs are accurate in those conditions. The short duration spike at 4 minutes could be an anomaly, but you do have two longer spikes of around 190 BPM at around 7 minutes and 37 minutes.

I wonder if your trace is asymptomatic AF as your pace was circa 12 minutes / mile. Unless you're incredibly fit, your heart rate dropped dramatically when you were walking. I used to get that back in the day during hard Spin classes when the drop in heart rate felt like riding into a hedge; I hadn't been diagnosed as having AF then.

The Bruce Protocol treadmill test will probably show if you have exercise induced AF, but you will need an EP to interpret it.

As a separate and unrelated point, your 70% - 80% maximum HR (MHR) looks as though you might be using 220 minus age, and that might be causing you some concern. The Metzl heart rate is reckoned to be better suited for older fit people. I've resumed the gym this month (April) after a year off caused by dronedarone induced cryptogenic organising pneumonia affecting both lungs ; the dronedarone was prescribed for PAF. The Metzl calc. gives me an 80% MHR of 145 BPM at age 68 with a resting pulse of 52. That sits nicely with the Bruce Protocol test showing the tendency to AF above 155bpm. I've found that 20 minutes on a rowing machine at around 100 watts (I used to do 170+ watts) plus 20 minutes on an Ascent Elliptical at level 1 (it used to be level 11) gives a steady 148 to 150 BPM with no sign of AF.

Good luck with the stress test.


Thanks John, I'm 46 I wouldn't say incredibly fit, but I have been running for a number of years.

As far as I know I can feel straight away when my heart starts playing up. I am very aware of the wobble in my chest. Although it's difficult to feel it during exercise

Regarding the Heart rate zones, in this case I just planned to run at that rate to test the features of the watch. As it turned out I quickly went through the planned HR zone while still "running" at an intentionally shuffling pace

Hopefully I'll get a referral from the doc tomorrow to do some further tests


I went to the docs. He sent me for blood tests (not sure what he was looking for) and i had to book in for another ECG with the nurse at the suregery

At the follow up he said my bloods were ok and no issues with ECG. He then paused and asked if i still wanted to be referred further up the chain but implied that all was ok and i should carry on exercising

I mentioned a treadmill test and he said that they are only used to look for angina. I also mentioned being referred to an EP, but he dismissed this and said that he will refer me to a cardiologist

As I had mentioned to him the HR readings he also dismissed this, suggesting people get too anxious & focused on what the monitors are showing. I can understand this to a degree but would like reassurance based on previous knowledge of my HR readings during exercise and now with the AF in the background

Lets see what happens

I am a very experienced runner and I have had the exact same experience when running in AF. I use a Polar V800 - same technology and HR sensor. If the HR actually increases at the end of the session then I suspect you have been in AF during the run. If in sinus rhythm the HR will drop at the end of exercise, if not if will probably increase a bit before reducing. Looking at your trace that is what is happening. Your HR was fairly high given that you were taking it easy. Your HRM is really measuring the faster irregular beats caused by the AF. The exercise tends to dampen the effect a little but when you stop you get an increase before it drops back down again. Polar HRMs are very reliable, so that is probably an accurate trace. You can see the variablity caused by the AF especially at the end of the session. You do not state what your would expect your HR to be given the exercise load, that might be useful information.

Do not stop doing what you are doing, but I would be wary of the Docs dismissal of this finding. I think it needs further investigation if it worries you.

jondeanp in reply to rmclachlan

Thanks for your reply.

I have been aiming to keep under 140bpm for the effort I was putting in.

I tried another little run last night and my HRM was reading 160's before starting although I couldn't feel anything unusual by pulse

I went out and the HR according to monitor was up and down like a yoyo until about 15 mins in. I had a bit of a walk and following that the HR seemed to smooth out to 'normal' readings

I'd like to run without the HRM so I can ignore it, but I've ran with one for 20 years and like to see what real effort I'm pushing

Also I'd like to be told by a professional what is really happening, whether it is 'just' AF or something else

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