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Treadmill test vs Polar M400 HRM

Treadmill test vs Polar M400 HRM

I was cardioverted successfully approx 18 months ago and no longer on any medication.

After a period, once i felt confident, i began to get back into my running. I have always used a HRM as a training tool and thought it was also the time for me to upgrade to a more up-to-date model.

As i have posted before i was seeing some strange readings on my HRM along with not feeling "quite right" ended up asking my doctor to refer me to a specialist at QE Hospital, Birmingham.

He did a static ECG and said i should be ok to run, but agreed to get me in for a treadmill test. He thought the feelings i was getting were just from a lack of fitness.

Last Friday i went for the treadmill test and the operator said he wanted to see me stay on it until i could go no more. He said he wanted me reach Max HR.

I did stay on the test until approx 98% of Max HR ( i think anyway) . I was too busy trying to catch my breath to get the detail.

They said that all looked ok. My heart rhythm stayed ok apart from 6 ectopic beats that they spotted. This made me feel a lot more confident about the stresses during exercise.

Last night i went out for my first run since April (when i asked to be referred). I wore the HRM but purposely avoided looking at the readings.

I looked at them this morning and once again the HR is all over the place. I will try my older version HRM but cannot get the same level of detail ie no graphs.

Does anyone else have any experience with their HRM readings particularly the Polar M400?

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I have both a simple Polar chest-strap monitor, and also a MIO-ALPHA wrist monitor. The latter was more expensive and probably works better, but both work unless I have an arrhythmia, then they both give incorrect readings but in different ways, as I've worn them at the same time to see what happens.

At the Patients Day, an EP told us why these monitors cannot always give true readings when you are in AF. I think he said because they cannot always tell what is and what isn't a heart beat. He told us best to just go with how we feel or use a stethoscope and listen to your heart.

With my Polar, if I get an arrhythmia it jumps up to 200 and sticks there, but I know my heart rate isn't anywhere near that. I've also had false readings from a large hospital monitor in A&E.

Other people on here say they work fine though, so guess it depends on the arrhythmia?


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I use a Polar monitor, not the 400 an older one, and it's only accurate around 80% of the time, and I am in peristent AF, sometimes reads way over 200 for heart rate even when I know that not to be the case.

I don't think any of them can cope with a heart rate in AF, as a doctor said to me, which heart beat do they measure? My heart beats sounds like a pair of trainers in a tumble dryer.

But that does no explain why it's happening for you if you are not in AF if I am honest

Be well



Thanks Koll & Ian.

Yes i can understand the readings if i was in AF, even for brief periods, but going by the recent treadmill test it appears that even under hard conditions my heart stayed in a good rhythm.

Hopefully i will be going back to the consultant once he has reviewed the data. I will ask him again if he can explain my HRM results.

The other thing that i also need to rule out is a genuinely faulty unit. If that is possible

Faulty heart or faulty HRM ;-)




Like the trainers in a tumble dryer comparison ,Ian. description yet ! Sandra

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I have an Alivecor and have never had a polar monitor but The recording above looks in the same format. It doesn't look like a 205 bpm reading to me but it does Look like electrical interference.

Did you feel as though your heart was racing at 205?



You had a cardioversion 18 months ago. Presumably you had Persistent AF? Or a Paroxysmal episode that you or someone felt had gone on long enough. But a cardioversion is no cure for AF, I'm sure you know that. You'll also know that the AF condition rarely goes away - it's usually progressive. You probably still have AF.

Your workout to Max HR, stressful though it was, would not necessarily trigger an AF episode and in your case it didn't. But after your recent run you noticed that your "HR is all over the place". Why do you think this is a fault with the HRM and not simply the fact that you were in AF?

No medication?


Hi I am down for a pre assessment and cardio version in October. Dreading it , dentist excepted not had an anesthetic since the late 70s and I felt foul for quite while.

The procedure itself sounds dauntng so naturally checked it out on the web. Most sites say its common procedure for AF, and though it sounds hit and miss wondered why fallingtopieces wrote its no cure.


Let me assure you, there is nothing to worry about when having a cardioversion - I've had several. The whole procedure takes barely ten minutes and you will know nothing about it as its usual to have a general anaesthetic. It's so lovely to wake with a normal heart rate. Hope it's successful for you.



not sure which worries me most the procedure or the effects of anesthetics. In response to RobertElee - yes its a cardio-version.

it would be about 6 weeks post diagnosis .

I was kind of hoping it would avoid an ablation

-so will be disappointed if it is no cure at all - Is it another of those sticking plaster jobs and just a quick temporary fix ?

I shall have to be sure I have a list of questions at the pre check up session


Ok Constabule. One of purposes of cardioversion, apart from ending your current AF session, is for the medics to see that you can be cardioverted. If you can, then that bodes well for a successful ablation should you chose to go down that route.

And though I know it can be a difficult decision, particularly if you really worry about these things, believe me it's the only option open for us to say goodbye to this damn condition. It may not work first time, or even second but if you're willing to give it a go there's a very good chance you really will get your life back.


thanks , I think if i stopped feeling done in that might help .Just rang the hospital to see if I could get the date changed (decided to go with date set) - told they did one today and one guy said he already felt ten times better.


And you will too. As soon as your heart goes back into normal sinus rhythm you'll feel so much better. And as jeanjeannie and others have said, a cardioversion is absolutely nothing to worry about - it's all over in a few minutes.

But, and I'm sorry to labour this point, it's important to prepare yourself for the fact that it probably won't last. If you want something more permanent after this, then you will have to start thinking about an ablation.



I think it's a bit unfair for Robert to dismiss the cardioversion in favour of the ablation as the only way to "cure" AF

I have been 18 months free of AF with no medication following a cardioversion.

You should take it one step at a time. Get the cardioversion out of the way and see how that goes.

You may need to continue on some medication.

Personally, looking at other posts, I would have more concerns with the ablation process due to the success rates with that, than taking medication if that kept things under control.


Time will tell - as others have said on other issues everyone reacts differently.

I think once the cardio and a CT scan is sorted I will know a little more and it helps picking discussing things here too.


I wrote it's no cure. A cardioversion simply stops a current AF episode (assuming it's successful). You could have another episode start minutes later or months later. But sure as eggs are eggs you still have AF and you will certainly have another AF episode. Sorry but that's how AF is.

Are you confusing a cardioversion with an ablation. Two very different things. An ablation could well be a cure - you may never have another AF episode again, though not everyone is that lucky first time around.

But a cardioversion - the electrical shock of the heart with the paddles - is nothing like an AF cure. Sorry.


I had persistent AF for 5 months prior to the cardioversion. After a few weeks post op my meds (Bisoprolol & warfarin) were stopped.

I have since had an ECG at the docs, one at the hospital and during my treadmill test. On all of these occasions my heart was in normal rhythm.

However when i monitor using my HRM the pulse fluctuates greatly even prior to exercise. For that reason i question the HRM reading.

I understand that AF is likely to return, but to date i have had no further episodes that i have been aware of.

Constabule, the cardioversion procedure is nothing to be worried about. The hospital where i had my procedure done said they had a 100% success in getting people back into rhythm, however there was no telling how long you will stay in rhythm.


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