Measuring exercise intolerance

[Sarah Tee]

Is there a way to measure exercise intolerance? I’ve had a bit of a read, but most of the tests seem to be looking at heart function, and I don’t have any heart problems.

Is there a test that looks at how quickly your muscles fatigue?

I have measured exercise intolerance myself at home by how many squats I can (or can’t!) do, but it would be nice to have something official that I can wave at doctors.

[MTRJ75]

I think there have been some more in depth studies, but I'm not aware of any universally available tests that measures much more than heart function. I'd be interested in this too, both from a muscle exhaustion & neuropathic activation sense. I really get lit up all over my body with any kind of extended exertion (ie light cleaning). 

[Sarah Tee]

@MTRJ75, I might be seeing a physiotherapist soon and will ask if they have any thoughts. Presumably they can test muscle strength and endurance.

I suddenly remembered reading about a test that is given to people with chronic fatigue syndrome by one of the centres/specialists in the US. I will just dig around and see if I can find it.

It was described as being very comprehensive but also exhausting and often putting people into a flare. (It wasn’t only for CFS, but that is where I happened to read about it.)

[Sarah Tee]

Okay, found it. It is called an invasive CPET or iCPET, and the person who has used it to investigate CFS is Dr David Systrom.

Info about the test:

https://www.uclahealth.org/medical-services/pulmonary/pvd/conditions-treatments/invasive-cardiopulmonary-exercise-testing-icpet

Some of Dr Systrom’s research:

https://journal.chestnet.org/article/S0012-3692(21)00256-7/fulltext

It seems like the standard CPET is fairly widely available but the iCPET is specialised. Do correct me anyone if I’m wrong.

Both do however seem to be aimed at investigating shortness of breath, although maybe Dr S uses them to look at it in a different way.

I do get a bit puffed when I’m symptomatic, but I don’t think I have actual shortness of breath. Maybe if I went for a jog? Usually I notice my exercise intolerance at home when climbing the stairs or doing squats. Mine is more like having no energy reserves to power my muscles than being short of breath.

Edited to add: There are also references to a two-day CPET. That is having the test twice, on consecutive days.

https://www.healthrising.org/blog/2019/01/17/decoding-2-day-cpet-chronic-fatigue-syndrome/

https://neuroimmune.cornell.edu/research/physiology/

[MTRJ75]

Yeah, that's the issue I meant with "universally" available. You'd have to travel to one of the few specialists in the country. 

[Sarah Tee]

Bummer.

I really need to win Tattslotto so I can buy all the testing equipment I want and set it up in Australia somewhere. If i won enough I could set up my own autonomic lab, although I don’t know who would staff it here.

[MikeO]

Not sure how one would test exercise intolerance or even muscle fatigue outside of reported symptoms coupled with maybe some vitals. I can tell you for sure if my BG level is 300 i am only good for a few minutes on the treadmill vs 100 and going for 45 minutes without any fatigue.  

[Sarah Tee]

@MikeO, I’m guessing sports scientists can test it. I feel jealous of their equipment and testing sometimes – imagine if that was made available to sick people. But we are not glamorous or money spinning.

Maybe it’s just as simple as asking the patient to do certain things until they have to stop, like squats or climbing stairs or treadmill, as you say.

But doctors do love an objective measurement!

[MikeO]

17 minutes ago, Sarah Tee said:

But doctors do love an objective measurement!

I agree but unfortunately insurance companies don't always look at this in the same light unless there is a protocol or return on there investment. In Wisconsin it is like pulling teeth to get any autonomic testing done. The major healthcare and universities are all capable but choose to limit what testing is done to (tilt and if you are lucky a QSART along with antibody body testing for RA etc if you get the point). Protocol is to make assumptions based on the few tests done as the treatments really does change let's say for nOH,OH,OI,NCS etc.... 

Edit: I think i just said the same thing you did. 

[RecipeForDisaster]

4 hours ago, Sarah Tee said:

Okay, found it. It is called an invasive CPET or iCPET, and the person who has used it to investigate CFS is Dr David Systrom.

Info about the test:

https://www.uclahealth.org/medical-services/pulmonary/pvd/conditions-treatments/invasive-cardiopulmonary-exercise-testing-icpet

Some of Dr Systrom’s research:

https://journal.chestnet.org/article/S0012-3692(21)00256-7/fulltext

It seems like the standard CPET is fairly widely available but the iCPET is specialised. Do correct me anyone if I’m wrong.

Both do however seem to be aimed at investigating shortness of breath, although maybe Dr S uses them to look at it in a different way.

I do get a bit puffed when I’m symptomatic, but I don’t think I have actual shortness of breath. Maybe if I went for a jog? Usually I notice my exercise intolerance at home when climbing the stairs or doing squats. Mine is more like having no energy reserves to power my muscles than being short of breath.

Edited to add: There are also references to a two-day CPET. That is having the test twice, on consecutive days.

https://www.healthrising.org/blog/2019/01/17/decoding-2-day-cpet-chronic-fatigue-syndrome/

https://neuroimmune.cornell.edu/research/physiology/

My friend had this. It’s pretty invasive, and yes, harder to find than a regular CPET. You do exercise hard, with catheters, so I think I’d be short of breath. She "failed"(notable findings) with very low preload during exercise, and didn’t end up having any recommendations for it in the end. She wanted me to also do the test, and I’m glad I didn’t, because she is back where she started. She has actual POTS and I don’t.

[Sarah Tee]

@RecipeForDisaster, I’m sorry to hear your friend didn’t get any progress from having the test. I imagine it might have cost a lot of money too. Oh dear.

[GasconAlex]

There are machines that objectively measure the ability of muscles to work. When I was in neuro rehab they had machines attached to computers that resembled weight machines but measured both repetitions, length of travel and fatigue for the arm joints and leg joints whilst seated. You sat down and then did a minute (or 30 seconds) of arm curls, leg curls, butterfly etc. with the machine both supplying resistance and measuring force applied etc.. 

The machine was mostly used to have objective measurements to show recuperation of function after strokes or head trauma. They were non invasive and clearly showed both progression and fatigue in the muscles whilst simultaneously measuring heart rate and breathing rates.

The set up could easily be used to show exercise intolerance too. I don't have the makers name or links as I never used this myself but have seen several people using the setup and having the results graphs compared and explained by the physiotherapists who conducted the testing.

[RecipeForDisaster]

4 hours ago, Sarah Tee said:

@RecipeForDisaster, I’m sorry to hear your friend didn’t get any progress from having the test. I imagine it might have cost a lot of money too. Oh dear.

It did. The arterial line and jugular cath are more important to me than the money, personallyI guess Systrom can deduce mitochondrial function using this test. He also really wanted me to do it. I’m relieved that I didn’t - mine would likely come up with the same findings as my friend. Basically, he offered her Mestinon if she wanted, and that was it, permanently. I’m already on it.

[Pistol]

I had PT once after an extreme bout of POT left me bedbound for a while. They wanted to get me reconditioned again. the therapist determined my level of OI bu having me stand holding on to a counter until I became symptomatic and my HR went up. ( I started with 35 sec three times in a row, and after a few weeks I could consistently do 2 minutes. )

They determined my exercise tolerance by starting me with supine exercises then sitting then standing. Each time I started an exercise they determined how long I could do it until I became short of breath, shaky and weak. And again they used my HR readings. These readings were used to establish my baseline. 

[Sarah Tee]

@Pistol, that sounds like a very sensible approach. If I am called on to document/prove my exercise intolerance, I will organise a physio to evaluate me.

My specialist is going through one of his occasional annoying phases and suddenly asked me for evidence that a treatment worked (beyond my saying that I felt better, could do more, etc.).

I am hoping he will return to being helpful next time I see him, but just in case I want to have some ideas on this.

[MikeO]

57 minutes ago, Sarah Tee said:

@Pistol, that sounds like a very sensible approach. If I am called on to document/prove my exercise intolerance, I will organise a physio to evaluate me.

My specialist is going through one of his occasional annoying phases and suddenly asked me for evidence that a treatment worked (beyond my saying that I felt better, could do more, etc.).

I am hoping he will return to being helpful next time I see him, but just in case I want to have some ideas on this.

Good Luck!