What empirical evidence is there that heart-rate monitoring helps avoid PEM?

[Sasha]

Yes it is. If you’re tracking a warning sign symptom to avoid doing too much. That’s a part of pacing and is used to avoid PEM.

Thanks, I hadn't been aware - but is that only PwME who get this when they do a bit much or does getting a useful warning apply to other people? Do we have evidence that avoiding tachycardia helps avoid PEM? (I'm completely ignorant about this area and none of it is making intuitive sense to me!)

 

[Kitty]

Wow I get lactic acid buildup from having a shower

Oh I get rapidly failing muscles too, but I'm not convinced it's the same thing. I'm not measuring my lactic acid balance, of course, but it's not the familiar experience I had as a competitive swimmer and hillwalker. Even though it can burn, it doesn't feel like having to work through acid buildup.

That's as scientific as I can get with it, though, which obviously is not-very!

 

[hotblack]

When healthy and running my heart-rate was well into the mid 100s when doing so and I felt fine. Since ME/CFS if it goes above 80 I’m iffy and over 90 I can barely stand up and am screwed. Cause or effect is questionable but there’s at least a strong correlation here. Doing what I can to keep HR low (in various ways) is in my experience helpful. This is a very brief description but I think that’s why some of us monitor, our lived experiences. No idea of empirical evidence or widespread usefulness for all people with ME/CFS though

 

[Yann04]

Yeah. It’s just a personal experience thing. Obviously in humans heart rate does correlate with physical exertion. So maybe that’s where the logic comes from.

But I don’t see it any different to getting a headache and just interpreting that as a sign to slow down. (That’s what I do with both headache and fast HR). I feel awful whenever my HR passes 90ish anyways and it nearly always seems to coincide with getting PEM next couple days. Having an alarm at 85ish allows me not to get to that point where I feel awful usually.

 

[bobbler]

some people get tachycardia when theyrr doing too much. sometimes you dont notice it. setting an alert or tracking throughout the day can help you see if you might be overdoing it

And on different days eg when someone might be less well the same person doing the same activity or exertion (or even non-exertion) might have a different heart rate because they are less well.

Or note with surprise that whilst not having got whatever app for such specifically when they did x they hadn’t been realising it was an exercise because maybe it was a mundane seeming thing you just do the same as before getting ill.

I wouldn’t think it is right for people to assume all those who are intrigued by that and find it validating that when they feel awful a few mins into the shower or sitting up or whatever their level is then it isn’t just their imagination are analysing lots or doing other things.

I’ll be intrigued to find the detailed threads on here of those who might have used them and done this but I must have missed them as the ones I’ve seen have more been touching on whether people would or do find them useful and quite sparse ie I don’t remember them going on for many pages. Or talk in too much detail at this level. I don’t think they’ve got to the stage of yet linking previous days exertion to later days hr or whatnot accurately but is it that some are collecting aggregated to see if there are possibilities of this pattern-wise?

I assume maybe some of the smart watch type things or apps have their own fb or other pages where there might be more ? I don’t know because I’d guess it’s tricky with the personal data type issues.

 

[bobbler]

So would I be right in saying that there's actually no study-based science showing that heart-rate monitoring helps avoid PEM?

Have you had a look for any studies?

When was visible actually released out of pilot stage? I think it’s all pretty new isn’t it?

 

[Yann04]

So would I be right in saying that there's actually no study-based science showing that heart-rate monitoring helps avoid PEM?

I don’t think it’s been seriously studied in that regard. (And hard to given PEM is subjective and HRM pacing is unblindable, like normal pacing).

I don’t think we have high quality evidence pacing reduces PEM either. It’s more a by definition thing.

Pacing makes you do less. Doing lots triggers PEM.

In that context HRM is just a tool to aid with the pacing.

 

[Jonathan Edwards]

So would I be right in saying that there's actually no study-based science showing that heart-rate monitoring helps avoid PEM?

I think you can bepretty sure that we don't have study based evidence. The studies would need continuous tracking over time, with regular reports of symptoms - the sort of study we have discussed being a good idea but not so far done.

I get a clear impression from people with ME/CFS that PEM depends both on intensity of exertion and duration of exertion. That immediately means that it is not going to correlate simply with heart rate. I don't think Workwell have any evidence for their claim relating to AT.

 

[Trish]

Elite endurance athletes such as road cyclists wear heart monitors which are continuously monitored to ensure they don't go over their limit. There may be something from sports science that's relevant.

A lot of heart monitoring is keeping people in their training zones. It's carefully staged building up to competitions, and it's done to ensure they're training at the level they need to be at that particular time—they might be overdoing it, but they could also be under-doing it. During competitions data is collected to inform future training.

Ultimately it's geared to pushing their performance limits as far as they can sustain. I'm not sure how useful the techniques would be to people whose need for measurements nearly always arises because they need to do less than they currently are.

My point is that of course for ME/CFS the purpose is completely different. It's about limiting exertion, so the level at which we are 'overdoing it' would be much lower than for elite athletes. It's more the fact that heart rate is a useful guide to amount of exertion that I think is relevant.

I agree with those who say there probably isn't adequate evidence for any specific calculation of maximum heart rate to stay below will guarantee avoiding PEM, but I think individuals who are interested in tracking can find levels to stay within as much as possible that reduce their chances of PEM.

Using it alongside symptoms can help with pacing, giving objective evidence of exertion that helps the pwME remind themselves to take a break. Some people also find if they use a monitor with an alarm it's a helpful way of informing family members, friends, carers, even employers, that the pwME needs to stop and rest.

 

[bobbler]

Sasha said:
Workwell suggest that for PwME, the AT threshold can be best estimated at resting heartrate plus 15 bpm, which barely allows scope to climb a few steps, or walk a few dozen yards.

I'd value @Snow Leopard's view on that. It sounds like proper codswallop to me—either that or that they're muddling up PEM threshold with anaerobic threshold.

I don't think the precise moment that's called the AT is obvious to the person working out, but the state of anaerobic energy production does become obvious after a bit. I swim laps of freestyle when I'm well enough, and I don't experience that sensation of lactic acid build-up even when I'm training at 85% of my notional maximal heart rate. I haven't felt it since I last went hillwalking in the 1990s.

I'd feel more comfortable if there were actual references/quotes as I'm not sure that is precisely what they said and for all of this it is actually about the specifics because the slightly different summary would mean something quite different

There is a difference between saying something is being used as a proxy to help someone be aware and saying something 'is it'. They know what they measured in the 2-day CPET with many more measurements was 'the AT'. Which is an exercise intensity.

From the actual text that @MrMagoo it talks about 'when you feel symptoms' and then talks of the HR numbers as a 'guide' ie they are trying to help people to be aware in order to help them zero in , and do not appear to be saying that someone would get PEM from 1 sec of crossing that 15bpm, so I'm getting a bit confused without the clarity of which bit we are questioning or if there is misinterpretation going on etc.

 

[MrMagoo]

Oh I get rapidly failing muscles too, but I'm not convinced it's the same thing. I'm not measuring my lactic acid balance, of course, but it's not the familiar experience I had as a competitive swimmer and hillwalker. Even though it can burn, it doesn't feel like having to work through acid buildup.

That's as scientific as I can get with it, though, which obviously is not-very!

I mean it hurts to bend my legs afterwards and they burn and seize and are stiff.

 

[MrMagoo]

I think that if you look at the workwell foundation info, they are claiming that keeping heart rate low leads to less PEM. The document is here and there are only two studies cited. They refer to the 2 day CPET test.

https://workwellfoundation.org/wp-content/uploads/2023/01/HRM-Factsheet.pdf

I don’t know that they have the evidence base to make the claims about reducing anaerobic heart rate leads to reduced PEM, I suspect it’s just that broadly, understanding what is a demanding task and limiting it helps avoid certain crashes and PEM.

People love this basic “bio hack” stuff and want things down to the calorie/heart rate/tiny unit. As if you never go 15 above RHR you’ll never get PEM that’s not how it works. The same as if you never smoke, eat “clean” and run every week you won’t have a heart attack or get cancer.

 

[MrMagoo]

I found this am sure we had a thread on it

https://www.robots.ox.ac.uk/~mosb/public/pdf/3535/Aitken%20et%20al.%20-%202024%20-%20Smartphone-based%20monitoring%20of%20heart%20rate%20variability%20and%20resting%20heart%20rate%20predicts%20variability%20in.pdf

 

[Jonathan Edwards]

I found this am sure we had a thread on it

https://www.robots.ox.ac.uk/~mosb/public/pdf/3535/Aitken%20et%20al.%20-%202024%20-%20Smartphone-based%20monitoring%20of%20heart%20rate%20variability%20and%20resting%20heart%20rate%20predicts%20variability%20in.pdf

I seem to have missed that or may have imply agreed with Snow Leopard's posts:

Note the non random effects model had very poor predictivity - AUC of 0.6-0.61 for crashes or brain fog.

This means in the real world, HRV and HR monitoring is not terribly useful because most people will not have a perfectly fit model, and even if they did, that doesn't tell them much about the specific triggers nor any treatments that prevents the response.

At least this study does confirm that people are worse after activity as monitored by heart rate. But a daylight monitor is not that useful to tell if it is sunny or cloudy. You already know.

I am also not entirely sure that they have ruled out the results simply showing normal fatigue. If I do a lot during the day (two days ago I dragged a dinghy on a trolley half a mile up a hill) I tend to feel dead beat that evening. Their definition of crash seemed a bit vague.

 

[Sasha]

When healthy and running my heart-rate was well into the mid 100s when doing so and I felt fine. Since ME/CFS if it goes above 80 I’m iffy and over 90 I can barely stand up and am screwed. Cause or effect is questionable but there’s at least a strong correlation here. Doing what I can to keep HR low (in various ways) is in my experience helpful. This is a very brief description but I think that’s why some of us monitor, our lived experiences. No idea of empirical evidence or widespread usefulness for all people with ME/CFS though

But if you're going by whether you feel fine or not, why not simply go by whether you feel fine, rather than going by an HR threshold?

 

[Sasha]

I think you can bepretty sure that we don't have study based evidence. The studies would need continuous tracking over time, with regular reports of symptoms - the sort of study we have discussed being a good idea but not so far done.

I've been wondering what a good study would look like, because obviously it would be unblinded, so you couldn't trust subjective reports, and the only objective measure would be something like step count - but because pacing is a management tool, not a treatment intervention, success might look like a reduction in steps (to the point where the PwME was PEM-free), or an increase in steps (because careful pacing was allowing more activity by spreading it throughout the day) or no change (because both of those things were in play).

I get a clear impression from people with ME/CFS that PEM depends both on intensity of exertion and duration of exertion. That immediately means that it is not going to correlate simply with heart rate. I don't think Workwell have any evidence for their claim relating to AT.

Yes, I'd agree on PEM being triggered by intense activity or lengthy activity is true, although particularly the latter might be PEM being triggered by OI that has been triggered by needing to be upright for a long time to do that lengthy activity.

In a health person, does heart rate not go up over time if they've been steadily doing an easy activity (like steady walking) for a long time? (I wonder if it does in PwME?)

 

[OrganicChilli]

In a health person, does heart rate not go up over time if they've been steadily doing an easy activity (like steady walking) for a long time? (I wonder if it does in PwME?)

My heart rate is fairly consistent when I walk slowly and was really low when I was on beta blockers. I'm still out of breath after 30m and walking reliably triggers PEM unlike cooking or taking a shower where my heart rate is higher.

 

[hotblack]

But if you're going by whether you feel fine or not, why not simply go by whether you feel fine, rather than going by an HR threshold?

That isn’t what I was tying to say. Take a look at my previous post, this is at least partially about HR, HRV and PEM. There seems to be a predictive element or at least something which helped in learning about what activities could trigger problems. If you wait until you feel bad it is too late.

 

[hotblack]

and the only objective measure would be something like step count

I found step count useless. Things that aren’t steps show up as steps and other activities which can triggering PEM are not counted. It was completely useless for someone who is severe and walks only a handful of steps a day.

Perhaps finding a good objective and truly accurate proxy is very difficult for some of us. Things like steps may be useful when we’re looking at much bigger changes/improvements but for management, less so. It’s a difficult one, but good to think about

 

[Trish]

I understand step count is useless for those only able to walk a few steps a day. But it shouldn't be dismissed for everyone. I found reducing my steps from over 2000 per day to around 1000 a few years ago cut the frequency of PEM very significantly, improving my quality of life.

And activities like getting dressed added to the step count makes sense in my case as it is noticeable exertion.

On the other hand sitting quietly knitting can add thousands of 'steps' on a Fitbit without being anywhere near the equivalent of walking that many steps, as my daughter has found. She says it records about 4 steps per stitch.