Thursday, February 03, 2011

Heart Rate and Post-Exertional Crashes in ME/CFS

My treasured heart rate monitor tells me when I've gone past my limits

(Updated in 2023)

I want to explain what I've learned in the last couple of months about how monitoring heart rate can help someone with ME/CFS (myalgic encephalomyelitis / chronic fatigue syndrome) to avoid post-exertional malaise (PEM), more commonly known as crashes.  At the end of last year, I posted a link to an excellent article called "Pacing by Numbers: Using Your Heart Rate to Stay Inside the Energy Envelope," which explains how monitoring your pulse rate can help you to stay within your limits and avoid the crashes we are all so familiar with.  It's an excellent article - I highly recommend you read it - but I wanted to also tell you some of what I've learned from my own experiences recently. You can also read my own recently (August 2019) published article, Using a Heart Rate Monitor to Prevent Post-Exertional malaise in ME/CFS, on the ProHealth website.

I have no medical background (even though my family calls me Dr. Sue, Medicine Woman now!), so I will try to keep this simple, as I understand it, without too much medical jargon.

Why Do We Crash After Exertion?
We all know that one of the biggest and worst parts of ME/CFS is the exercise intolerance, also known as post-exertional malaise.  When we do too much, we feel terrible the next day (and often the day after that, and so on).  And "doing too much" for someone with ME/CFS could mean taking a shower or fixing lunch or taking a 10-minute walk.  If you want to know more about post-exertional malaise, I recommend Jennie Spotila's excellent series of articles on PEM.

One of the major reasons WHY (there are several) we feel so bad after exertion is because our cells don't handle oxygen the way they're supposed to, a condition known as oxidative stress.  When normal, healthy people exercise, their heart rates gradually increase (which is good for them!), in a process called aerobic exercise.  During this process, the cells are using oxygen in the energy-creating metabolic process within the mitochondria (kind of like tiny energy engines in our cells).  If a healthy person exercises for a long time and/or at high intensity, their cells switch to anaerobic metabolism.

People with ME/CFS have an extremely low anaerobic threshold because our cells don't handle oxygen appropriately, so that our bodies switch to anaerobic metabolism with very little exertion.  So, the effect of a short walk in someone with ME/CFS can be similar to the effects of a healthy person running a marathon.

You can estimate your anaerobic threshold (AT) using this formula:

(220 - your age) * 0.6 = anaerobic threshold or AT, in beats per minute
(that is, 60% of your maximum heart rate)
See my recent article for more detailed formulas, with more options for women and for those more severely ill.

I'm 45, so my anaerobic threshold is 105 beats per minute (note, that was in 2011 when I first wrote this post. As I am updating it here in 2019 at age 54, my AT is now estimated at 100 bpm, though in reality, it is higher than that - see below).

Note that this formula only provides an estimate of AT. The most accurate way to find out what yours is is to take part in a 2-day exercise test specifically designed for ME/CFS (a 2-day CPET test), but most of us don't have that opportunity. You can use the formula as an estimate and then test it out for yourself.

How Does OI Affect Post-Exertional Crashes?
Another significant factor in post-exertional crashes is Orthostatic Intolerance (OI), a condition that affects more than 97% of patients with ME/CFS (and many of those with fibromyalgia and Lyme, too).  OI is basically an inability to maintain a steady heart rate (HR) and/or blood pressure (BP) while upright, and it is behind many of the symptoms we experience as ME/CFS, even if you don't realize it (check out this past post on OI for more information).

Typically in ME/CFS (though not always), OI causes our heart rate to increase and our blood pressure to decrease, often substantially, when we are upright, either sitting or standing (though there are some rare cases in ME/CFS where the BP increases when upright or in some cases BP and HR jump around - those are still OI).  So, while a healthy 45-year old would probably not hit 105 beats per minute until she'd been exercising for a while, I can hit 105 just standing up.  The result is that even minor exertion can put someone with ME/CFS over their anaerobic threshold.

Tracking Heart Rate
So, monitoring or keeping track of your heart rate can give you a solid, quantifiable way to know when you've passed your limits and are in danger of experiencing post-exertional malaise (i.e. a crash).  You can check your pulse rate simply by touching your wrist or neck and counting the beats, but I highly recommend using a heart rate monitor.

I asked for and got a heart rate monitor for Christmas (thanks, honey!), and wearing it during my normal daily life has been enlightening.  I planned to wear it when I took a walk or went shopping or something else exerting, so I could tell when I had done too much.  On my first day, I decided to take a walk in our neighborhood, so I strapped it on, after calculating my anaerobic threshold (105).  I was shocked to see that my heart rate just standing in the kitchen was already over 100!  I bent down to tie my shoes, and my heart rate jumped up to 115!!  And I hadn't even left the house yet.

I did take a 15-minute walk that day, as slowly and carefully as I could, but my average heart rate was 103 and the maximum (after I had my shoes on) was 110.

Over the course of the next week, I wore the heart rate monitor almost all the time during the day and watched it constantly (some might say obsessively).  I found that it provided hard data to back up what I already knew about OI (I love data!). 

Even lying down (what's known as resting heart rate), my heart rate rarely went below 90.  Sitting on the couch with my feet up, it was often in the 90's or near 100.  Standing up to make a cup of tea could drive it over 100.  Taking a shower or putting in a load of laundry could spike it up to 130 or higher!  One day in the library, I noticed it was close to 100 just walking around slowly, but when I crouched down to see something on a low shelf, it dropped to 75-80.  I knew from Dr. Rowe's article on OI that crouching helped, but it was illuminating to see that for myself.  I also noticed that it varied from day to day, depending on how I felt. Research bears this out - your AT is even lower and your HR even higher when you feel worse.

On a grocery shopping trip, I discovered - much to my surprise - that the part of shopping that drove my heart rate highest was carrying the groceries into the house.  This was much more exerting to me than pushing the cart or walking around the store.

It was fascinating for me to see that my quietest day could easily put me over my anaerobic threshold fairly often.  No wonder I rarely felt good - I was in a constant cycle of post-exertional crashes without even "doing" anything!  I really had no idea that was happening.

Try it for yourself - monitor your heart rate for a few days.  Find out where your own anaerobic threshold is and how much exertion it takes to put you over it.  Experiment!  Try various normal daily activities and see which ones are within your limits and which push you beyond them.  Figure out how some simple changes can keep you from going past your threshold - maybe dividing tasks up into parts or resting in the middle or delegating certain things.

Choosing a Heart Rate Monitor (updated)
Although there are now many different kinds of wearable devices that can measure your heart rate, there are a couple of things to look for that you'll need specifically for ME/CFS: 

  • You want a heart rate monitor that continuously monitors your heart rate, giving a constant read-out. The kinds of devices that require you to push a button to check your heart rate aren't adequate for us. 
  • A large read-out that you can easily see is best. 
  • You also want to make sure that you can set audible alarms for heart rate that are custom to you. Some devices may just calculate your limits based on your age, but with ME/CFS, we are using it differently than that. You will set your upper limit to whatever your anaerobic threshold (AT) is, according to the formula above, and you want an audible alarm to inform you immediately if you hit that limit. 
  • All models now can link to a smart phone or computer, so you can see your data.

I have been very happy with my Mio Alpha heart rate monitor; however, they are no longer available (sometimes you can find one at that link by clicking on "available from other sellers"). There are, of course, now plenty of fitness trackers available, like Fitbit, that measure heart rate, though I find their HR read-outs quite small and hard to see while you are moving around, and they are designed for athletes and active people, with different settings for different sports and activities. They do, however, have additional features like sleep tracking.

Another option are the type with a chest strap, mostly made by Polar. Some people swear by these. I wore one for several years (and went through several chest straps) and found it was uncomfortable, inconvenient, and not all that accurate. Mine would cut out at random times and the newer ones required contact gel to perform even adequately. Some of my issues may have been simply because I'm a woman--I'm sure it's much easier to put a chest strap on in public when you're a man!

When I polled people with ME/CFS in several online support groups about what kind of heart rate monitor they used, many said that they loved their smart watches and they could do all that we need them to. Of course, Apple Watch started the smart watch thing, but now there are plenty of other options, too, like the Samsung Galaxy. I started using an Apple Watch in summer of 2023, and I have found it has some specific pros and cons for our use. The biggest downside is that you cannot set an upper limit alarm, so I added an app called Beat Watcher ($10), which does allow me to set an upper limit alarm but doesn't work with Apple's other built-in fitness apps (which tell me how long I was active, my highest HR during that period, heart rate variability, etc.). In this short video, I discuss the pros and cons of Apple Watch versus my old-school heart rate monitor.

I recently bought a fitness tracker to use as a heart rate monitor for my son (and his medical team wanted him to track his sleep, too). I looked at all of these options. At the time, smart watch prices looked very high, though they seem to be coming down. I also saw a bunch of very cheap trackers being sold as "smart watches," but I was unsure if they had all the features I list above. I finally settled on a Garmin Vivosmart 4. I read through its features carefully and also called Garmin tech support to make sure that you could set it to show HR continuously and could set your own upper limit for HR (yes to both). And it's only $99. That was three years ago, and I don't think he ever even took it out of the box, so I can't report on how it works, but I have heard others with ME/CFS like this brand/model.

Treating OI to Improve Stamina
For me, the monitoring only did so much - I was still over my limit during most daily tasks and could not manage even a short walk without crashing afterward. Then, I tried a new treatment that turned out to be life-changing for me! I now take beta blockers for my OI. Beta blockers block certain hormones in the body to bring heart rate down to more normal levels. As with everything else in ME/CFS, a lower dose is best for us, and it only takes a little bit to be effective (and too much beta blocker actually increases fatigue). Once I found the right beta blocker (there are several dozen to try) and the right dose for me (see tips in that link), my life was transformed. I could go grocery shopping, take walks, and get through normal daily activities, all without going over my limits and crashing. I still use my heart rate monitor, but now I only need it when I am doing something especially exerting, like walking or hiking. I am able to stay below my AT in my normal daily life and even cook again!

I have also found, as noted above, that my AT has actually increased, even though I am getting older, because I am now able to be more active and improve my fitness (all while staying below my limits). This has been born out in research, as explained in my recent ProHealth article: staying below your limits and preventing PEM (crashes) allows you to begin to improve your fitness level, which will gradually increase your AT...allowing you to do even more! It's a positive domino effect that I have seen work in real life.

Once you've determined where your limits are, you can try to stay within them as much as possible.  This should result in feeling better, and then you can try to very slowly and gradually do a bit more. This is NOT the dreaded Graded Exercise Therapy (GET), which can worsen your condition, but using science and quantifiable measurements to stay below your limits and prevent crashing. Treating Orthostatic Intolerance can help you to become even more active and further reduce post-exertional crashes. Good luck!  Let me know about your own experiences in monitoring heart rate. And if you want to dig more in-depth into this topic or chat with others with ME/CFS using heart rate monitors, join the Facebook Group ME/CFS - Pacing with a Heart Monitor.

UPDATE AS OF 8/21/19: Seven years after starting beta blockers - and with the help of my heart rate monitor - I have been able to greatly increase my physical stamina. I can now manage up to two hours of walking/hiking at a time (wearing my heart rate monitor and staying below my AT, of course!), without crashing afterward. I love the outdoors, and I have been gradually increasing the lengths of hikes I can manage - I did 1.5 miles on hilly terrain last summer! I have also started slowly doing some weight training - mostly on my back to keep my heart rate low and in the morning when my beta blockers are working best. I can now work out with weights for about 20-30 minutes most mornings and have increased my muscle tone substantially (which further improves OI). I rarely crash from over-exertion anymore, which has been life-changing for me. None of this would have been possible without first treating OI and using my heart rate monitor to stay within my limits.

Note: This post contains affiliate links. Purchases from these links provide a small commission to me, to help offset the time I spend writing for this blog, at no extra cost to you.


Anonymous said...

Thanks so much for this great info!!

dominique said...

Thanks for the update on your progress Sue.

I happen to stumble upon the article you mentioned and had it on my to do list.

I will read it this weekend and I think I'm going to try this as well. The fact that we would have a way to gage the boundaries is amazing.

Can you share a link on the machine your hubby got you?

Elaine said...

Amazing! My heart rate is high most of the time. I find this interesting.

Would it be ok for me to copy it and give it to my doc for his review? I wonder if this is why he thinks I may have a coagulation defect? It interferes with the oxygen distribution as the blood flow is impeded.

Hope you are feeling more rested.

Thanks so much.


Lee Lee said...

I have been using a heart rate monitor for several months and it's been invaluable in understanding why I often feel the way I do. I have learnt how to avoid things that push me way beyond where I should be going.
I do have one word of warning though. The realization that just standing up puts you over your threshold can inadvertently teach you to be a couch potato and end up making things much worse! The less you do the less you are able to do, so do monitor your heart rate but don't let it scare you into staing still all day!

Anonymous said...

Thanks for posting this Sue, I'm just sending off some emails to friends to see if anyone has a heart rate monitor that I can borrow and test out for myself.


Baffled said...

I am so glad you are writing about this. I'm looking forward to the next installment. Now I just have to wrestle my son for my heartrate monitor.

Sue Jackson said...

Dominique -
My heart rate monitor is Polar brand, which is one of the largest brands. Ken got me a really nice one for I think about $60, but I believe you can get them for around $30 and probably much less used. Most consist of a band you wear around your chest with a watch-like monitor you wear on your wrist. Any sporting goods store (regular or online) will sell them, as well as big stores like Wal-Mart, Target, etc. I had one years ago that I used pre-CFS so I could make sure I was getting my heart rate HIGH enough, but I couldn't find the chest band for it. This new one is great!

Elaine -
Yes, absolutely share this with your doctor - I would recommend printing for him the Pacing article I linked to and - even more important - the article on OI by Dr. Rowe.

Some doctors do believe people with CFS have a coagulation problem, though it's not a theory that's been proven. The problems with use of oxygen in the cells relate back to the fact that our mitochondria don't work properly - that affects energy production in the cells. The mitochondrial dysfunction is caused in part by endocrine dysfunction, which in turn is caused by immune system dysfunction, which is at the heart of ME/CFS. It's a vicious cycle, domino-effect. Good luck!


kitty said...

I read this article too and was impressed by it and wanted to try it, however when I told my sister who studies "sport and exercise science", and my dad who is a keen athlete about the anaerobic threshold calculation they both said it was wrong (a "normal" person's AT is much higher). I tried to find out if it was adjusted for someone who has ME/CFS, and how this was done, but wasn't given a clear answer. Does anyone know whether this is the case and how it has bee adjusted etc? Would be very interested to hear!

Nice to read about your progress, I need to find me a HR monitor!!!

Anonymous said...

There is an article at about exercise that includes talking about the use of a heart monitor (it is posted on my blog).

After reading your post though, Sue, I think it would drive me nuts wearing one of those! So I have decided not to get one!

You go girl!

Sue Jackson said...

Kitty -

yes, your Dad and your sister are exactly right, and that is part of the point here! Yes, our anaerobic threshold is much lower than a healthy person. For a healthy person, their anaerobic threshold is usually calculated at about 75-80% of their maximum heart rate. For people with CFS, it seems to be standard to consider the anaerobic threshold at about 60% of maximum, as the equation I posted shows. That is because our cells don't process oxygen properly, so we switch to anaerobic mode much more quickly than a healthy person. Sorry if I didn't make that clear in my post.

I don't know who came up with the 60% figure, but anyway, this calculation is just an estimation (and I should have said that). The Pacing article I linked to lists other ways to get a more accurate number, but I think for these purposes, an estimate works just fine.

Hope that helps to clarify a bit!

Judy -

You don't have to wear the heart monitor all the time. I've only been doing that as a starting point, to help figure out where my limits are and it's been very helpful. I find it especially helpful first thing in the morning, before my beta-blockers kick in, so that I know when it's ok to get up and be more active.

My initial thought was to just wear it during exercise or exertion (like grocery shopping or taking a walk or yoga), to avoid pushing myself too hard and crashing afterward...and I will probably switch to that sort of use when I feel I understand my normal daily limits better.

The results of wearing it so far are that I have not had a single bad crash from over-exertion in the past month! I have had some mild crashes due to stress (including today!), but the monitor is really helping me to avoid post-exertional crashes.


Renee said...

Excellent article Sue with so much good info. So glad you are doing well on the beta blockers....

Anonymous said...

Hmmm... good food for thought!

On another note, getting the heart rate up during cardio is soooo needed for a healthy heart---for normal people. Studies show it helps keep the arteries cleared from blockages that can lead to heart attacks (all that blood forcefully racing through the arteries!). Getting the heart rate high during exercise is good heart attack prevention.

On yet another note, where are the studies about the effects of weight training on CFIDS? I know for me it has increased my muscle strength to that of a normal person, and it is also improving my energy level.

Gives new meaning to "no pain no gain!"

Sue Jackson said...

Good point, Judy - I've always said that very brief, light weight-training is good for people with CFS. Weight training is generally anaerobic, as long as you don't do it long enough to raise your heart rate too much, and it is good for conditioning. You still have to be very careful not to cause a crash - for me, doing one exercise (less than 5 minutes) at a time, maybe 2 -3 times a day - only on my best days has worked in the past. Any more than that, and it causes a crash for me.

Yes, it is just another example of how people with CFS are the exact opposite of normal people - high sodium and not raising heart rate too much is best for us, just the opposite of what is best for healthies!!

Just remember, healthy or sick, pain is NEVER good when associated with exercise - that's been well-proven by now.


Anonymous said...

Right, but I keep saying that the more I do, the more I CAN do. My heart rate stays down (I guess) longer now than when first starting weight training, cardio too. Gradually increase your workouts maybe?

Didn't get any response to the part in the last post on my blog about being tortured by fatigue at night, yet not being able to go to sleep because of the timing.
I was hoping to hear from people who experience the same thing...

Maxine said...

Thanks Sue, excellent information!

Maxine said...

Sue, is it OK if I post a link to your blog on my Facebook page?

ZzirF said...

great report - I monitor too - very illuminating as you say.

Sue Jackson said...

Yes, Maxine - no problem! Glad it's been helpful.

Anonymous said...

I am in bed with my computer and two heating pads on a Saturday morning. I just read your post about heart I began to read it, I was thinking "yes, but my heart rate is always over 100, so how does that work?" I read on and got some answers. Thank you for your blog. I need to know that somebody else out there can become exhausted merely taking a shower. -Maureen

Anonymous said...

That is exciting, Sue! I'm debating whether to get a heart rate monitor or a blood pressure monitor. A lot of my exertional problems happen when sedentary and trying to mentally focus on work, like a slow suffocation effect... which I think may be associated with the types of blood pressure drops I get from standing and doing activity.

Could have BP on one arm, HR on the other arm I guess, lol!

Take care,

Baffled said...

Calculating anerobic threshold is a tad controversial even for a fit person. Yes, I was an exercise nerd before I got sick which is why I already own a heart rate monitor.

There are many methods for figuring out heart rate ranges and basically they are all guesses since you can't really get your max heart rate without medical supervision.

The easiest version is the 220-age and then pick the target workout range which in our case is 60% (multiply by 0.6) and for a healthy person would be in the 70-80% range (multiply by 0.7 or 0.8)

Here is a site that calculates AT for you using a different method but is for a fit person:
and, in my opinion, the numbers come out too high for us CFRers.
Here is a link with various methods of calculation explained:

I also found the source for the 60% rule for CFSers:
which is a great article on CFS and exercise.

Pamela said...

Very fascinating post, Sue - thanks as always for your insight! I've been asking for a heart rate monitor since I had the post exert study one on my at the University of the Pacific. They calculated my anaerobic threshold, which was quite high (dont remember exacdt number, but something above 150) in a regular state and very low (117) in a post-exert state. The recommendation was to keep my HR under 117 to prevent from going into a post exert state. Hard to do without a monitor... I may just buck up and buy one for myself, esp since it's been so useful for you!

Anonymous said...

I am a runner (don't have CFS) and wanted to point out a significant inaccuracy in your article. Anaerobic Threshold is absolutely NOT usually 60% of maximum heart rate. Typically it is in the range 85-90%.

The formula for maximum heart rate (220 - age) may work well for some people, but maximum heart rate is highly individual.

Using the formula and 60% figure my anaerobic threshold would be 105 bpm (I am 45). I would not even be able to do a slow jog at that rate. My EASY runs - up to 10 miles - start at 135 and drift up to 150 or so.

Using my actual maximum heart rate (205 - I have gotten it up that high during training to test it) and 85% of heart rate reserve (the proper way to calculate these things), I calculate my anaerobic threshold at 182. Based on my experience, that is about right.

Please see the following link:

Sue Jackson said...

Dear Runner -

yes! Exactly! You have pinpointed the reason WHY people with CFS are so disabled and unable to exercise. What I wrote was not inaccurate - those of us with CFS DO hit our anaerobic threshold at only 60% of maximum heart rate.

You say that using the 60% formula would give you an anaerobic threshold of only 105 bpm and you wouldn't be able to run at all without going over - YES! That is absolutely right. That is my anaerobic threshold, 105 (roughly), and I am certainly unable to run because if my HR goes above 105, I get very, very sick within hours and stay that way for days or even weeks.

Now perhaps you can understand why people with CFS are so horribly sick and disabled and why the exercise intolerance of CFS is its central distinguishing characteristic.

Believe me, we all wish we could run, but that's a distant dream for now.

Thanks for taking the time to read my post and leave a comment.


Jo said...

Oh, Sue! You rock! I can't thank you enough for all you share with us. This is so very helpful!

hkd said...

this is so helpful - and very well explained - i always have a very low blood pressure and high heart rate - but most doctors had missed that - so thankful that they aren't dealing with an elevated blood pressure! i am a data lover also! thanks sue

Anonymous said...

Sue, I am a first time reader. I have Ehlers-Danlos Syndrome type 3 (which comes with CFS and Fibro symptoms also). Your story sounds very farmialr to what I have been feeling. Over the last several days, my HR rarly droped below the 100's and if it did, just standing, it would climb up to 115 or so, let alone walking, working, taking care of the house and kids, etc. Wore a halter, doc said he couldn't explain it, but that it wasn't electrical bc my hr wasn't jumping it was gradually climbing. At one point in my Halter my HR was 170! Put me on some meds to use as needed. But am trying to figure out for myself why this is happening, what is causing it. Your post is very enlightening. Was your HR jumping or was it climbing gradually as mine was? Did your Cardio give you a diagnosis? I am glad to hear that your meds are working for you and very much appreciate your post. Know that you are not alone in your struggles, there are alot of us out there trying to figure this all out. Sounds like you've got a pretty good handle on it.

Sue Jackson said...

Hi and thanks for taking the time to stop by and comment! Glad you found my blog and thought this post was helpful.

The symptoms you describe are a part of Orthostatic Intolerance, a condition that affects over 97% of those with CFS, as well as many associated illnesses like EDS. Understanding OI and treating it can dramatically improve all of your symptoms.

Here is a post I wrote about OI - I highly recommend you also read the article that is linked in this post, by Dr. Rowe:

Good luck!


twenty six letters said...

Hi Sue, I'm in the UK so obviously availability might be different, but I read your article with interest - my blood pressure is low but my blood rate high (I'm depressingly typical for someone with CFS!), and this idea really makes sense to me. I read somewhere about people who had an alarm on their monitor so that they knew when they were approaching their AT, I wondered 1) does your monitor have that and 2) if it does, which model do you have? Trying to do some research, and some say they have an alarm, but don't specify whether it's a target based alarm or just one like on a watch. SOOO confused. But thank you for the article, it's given me a new idea and a new source of hope, which is always needed!

Sue Jackson said...

Hi, 26 -

I think most (if not all) heart rate monitors have alarms on them that you can set wherever you like. They are mainly designed for people wanting to get their heart rate HIGHER during exercise, but, of course, for us, we can set them to alarm lower. I use a Polar brand, but there are many others on the market as well.

Good luck - I hope it helps!


Patrick W. Calvin said...


Thanks for linking to this post in your recent comment on my blog. I had been recently thinking about getting a HR monitor, so your comment and link couldn't have come at a better time.



Glenda said...

This is such an enlightening and helpful article that I wish I had known about it earlier.Living in a regional country town without access to anyone other than a GP means there hasn't been much help in the offering apart from "just rest"
I have come a long way from 2000 when I first collapsed with ME but still it all seems like pot luck as to how much energy I am able to expend without a crash. Thank you so much for this timely info and wishing you all the best.

Gary said...

Hi, I know that keeping exercise to a minimum helps CFS, but it is also dangerous to not exert yourself and build muscle. It is a bit of a double-edged sword.

I tried exercising hard and ignoring the subsequent "crashes" for a long time, and eventually the amount of exhaustion for each peticular exercise went way down, I can now push myself a lot harder than I used to without feeling the crash. My heart beats like mad after compound exercises, my whole body shakes with each beat - but it keeps me fit.

Have you looked into Low Dose Naltrexone? I am going to get it from my doctor asap - have a read about it if you haven't already.

Happycakes said...

Connie Sol who works with Nancy Klimas claims she has seen anaeribic thresholds as low as 45% for pwCFIDS/ME.

Happycakes said...

I've read the anaerobic threshold for CFIDs can be as low as 45%.

Unknown said...

I am early in my heart rate monitor (HRM) usage; so far I've noticed on hot days I can rarely carry anything or do much with my arms without it beeping, but on cooler days I can do those same activities without going over. I also notice that after I eat, my monitor beeps more often.

However, I also notice that when I ignore the beeping (as I try to just finish one more thing before I obey the beeps and recline), it can stop beeping after about 30 sec of doing that activity - I assume my body may get used to the new position - which lends weight to the idea not to avoid activity altogether.

BTW I set my heart rate monitor to have a target zone of 30 - 115 bpm, that way it beeps when I exceed 115 which I am estimating is my threshold. (I had a 10 min exercise test that determined my threshold (AT) was 125, but that was on a day where I did nothing else but the test). The test said my max heart rate was 169 [the 220-age formula was actually 4 beats higher, but a pretty close estimate!].

Sue Jackson said...

Glad to hear you are getting some good info from the HRM!

Any kind of heat (especially hot water or steam but outdoor heat, too) is really bad for OI - heat dilates the blood vessels, making it even harder than usual to properly circulate blood to heart and brain.

Good luck with the new HRM!

Anonymous said...

Wow I am pacing and it's working but I wonder if it's because I'm staying below my threshold. Thank you for this information. It's fantastic :)

Sue Jackson said...

That's great! I hope your success continues!


Anonymous said...

Yes, the AT was adjusted for a person with ME/cfs. Normal AT is measured by 220 - (your age). For a person with ME/cfs it 220 - (your age) x by .6. When you take the 220 - (your age) and multiply it my .6 you are in effect getting a percentage that is 60% of your heart rate. That is what is recommended for ME/cfs patients to stay under.

Unknown said...

Thanks for this article. I have had CFS for the last 5.5 years. I was very bad for 3-4 months when I had to stop half way up the stairs and used a heart rate mointor as my heart was missing beats and found that my heart was racing up to 130 from a resting of about 40-50 (correct I have got it from my dad and have had loads of ECG's before and during my illness).

I have improved greatly over the years although I get a relapse if I am fighting a virus which can last from a few days to a few weeks sleeping. It feels like somebody is injecting me with a drug telling me to sleep and I can feel my body fighting infection.

Before my illness I was a very fit person and thankfully I have had a very good doc who is also an athlete. Her best advice that I couldn't do too much or too little. When I started to do a wee bit more exercise it was a natural thing to keep my heart rate low and it was over 2 years before I felt I was able to go for a jog but I could cycle.

Now I have mild CFS - I just have the fatigue - I work from home and I am self-employed and all my clients are very understanding as the urge for a nap can be very strong and I can have just a tired day.

My exercise is very much reduced than what it was but I still find that if my heart rate goes up too much I fell like I am going to blackout. Also if I exercise too much I get the same feeling. I play competitive volleyball when I can and the team can tell when I reach that point and the coach takes me off.

This article is great it has given me a reason why even after all this time I can't do aerobic exercise. I stick to body pump (although had a wee wobble this week at least the instructor believes me now!) and weight bearing exercise classes. I also cycle but now go out with a group who don't go too far with plenty of stops. I can still do hills if I just take it easy but if I push myself I have to stop. I walk lots with the dog and can manage about 5 miles max.

I know I am lucky that I don't feel ill just tired and odd days when I am completely fatigued. I am also lucky that I can still do some exercise although I do wish I could do more. I listen to my body and if it says no I don't do.

The only other characteristic of CFS that I have is chemical smells make me feel ill.

Sue Jackson said...

Alice -

Yes, you are lucky you have partially recovered and can do so much! that is great - I'm happy for you. You give the rest of us some hope.

If you want to be able to exercise more without crashing, you might consider treating your OI. Over 97% of those with CFS have some form of OI and it is very treatable and directly affects exercise capacity. Click the link in this post that says "past post on OI" to read more.


Unknown said...

Thanks Sue - Have always hated salt always wanted to eat crisps as a kid but just couldn't. I can taste one grain of salt on a chip I am that senstive. I eat salt only in the few processed food that I eat and that's it.

I do make up for it though I drink at least 2 litres of water a day and always have done.

It is just great to find more info on CFS and to find out that I am not quite so werid

Unknown said...

Wow in he space of a week I found out about why I can't exercise and I discovered electric mountain bikes. I live in the highlands of Scotland where there are few roads but 100's miles of trail easy through to crazy. At present I have to have a very good day to be able to go out and cycle 10 miles and then days to recover. Before the illness I used to cycle alot in all weathers in the dark at night in the winter and I miss it.

Last night I tested a full-suspension electric mountain bike and went 15 miles with the biggest grin on my face. The motor kicks in when you pedal and you can up the amount of assistance you need (which I have renamed good day, bad day and in-between). I took it on rocky single track up hills and all whilst keeping my heart rate within a very sensible level. Felt like I had exercised when I got back but this morning felt great - no extra tiredness so as the bike had to go back to the shop this morning I went out and have done another 12 miles again with a huge grin. Going back this afternoon to buy one this is going to make a huge difference to my life :-))

Sue Jackson said...

That's wonderful, Alice! I've never even heard of such a thing but it sounds like a lot of fun! I've considered getting my bike out to see how my heart rate does, but we live in a very hilly area. I like kayaking because it's done sitting down so my heart rate stays low, but I can get outdoors and propel myself!

Unknown said...

Sue try one of these bikes they will take you up the hills whilst keeping your heart rate low. See if you have a shop that will rent you one or loan you a demo you will certainly have a grin on your face afterwards and then you will have to buy one. You still pedal but at a rate you want to the motor does the rest. I aim to take the bike up a 2 mile track near my house which is a constant hill - I could do it in 35 minutes when I was fit. I haven't been to the top in nearly 6 years - 12 days til I get the bike can't wait

Anonymous said...

Finally! An easy way to find out (roughly) what my anaerobic threshold is. I have spoken to many people who use this information to help them pace, with very good results. While this calculation doesn't give me the complete picture of a VO2 max test, for those of us who don't have access to a clinic that can do this test, it's the next best thing. Thank you, thank you, thank you!

Unknown said...

This article has been the biggest help to me over the nearly 6 years that I have had CFS. Over the last 3 months I have kept my heart rate low as much as I can and I have had tired days but almost no fatigued days. I played a volleyball match on Sat and I expected and was fatigued for a few days afterwards (and every muscle hurts) but I had planned for it. Thanks for making such a difference I now know what I can and can't do and if I push myself what the after effects are

Sue Jackson said...

I'm so glad that this information has been helpful to you, Alice! And good for you for playing in your volleyball match! Very impressive!!

Now, if you want to take it a step further and lessen or even eliminate the 3-day crash afterward, you might want to consider beta blockers to help keep your heart rate down. They've helped me sooo much - I can be much more active now. Here's more info on our experiences:

Keep up the good work! I really admire you for working so hard to stay active.


Unknown said...

Thanks Sue, I naturally have a low heart rate and previous to CFS was given loads of ECG's I also would set off the alarms in hospital on the heart rate machines so I don't think that they will be suitable for me. I don't play many matches 4-6 a year so the crash afterwards is a small price to play.

I went for my first swim yesterday in over 3 years - I just kept the pace down and of course took my heart rate monitor. Managed 25 lengths and felt great afterwards and today.

I gave your article to my doc who is great as she is a very active and we used to compete in all sorts of events. She said that she would really struggle if she had CFS. As I have said before this article has helped me more than anything else I am much more active and far less tired I have just changed the activities that I do.

400 miles in 6 weeks on my new bike but the weather will prevent me going out much in the winter as it doesn't like the wet and cold so really looking forward to the summer although in Scotland they can be wet and cold too!!

Sue Jackson said...

So glad you are enjoying life and able to do the things that you like, Alice!!

Mr Mills said...

I find this post very interesting Sue. I have CFS and have a heart monitor as well. My experience with heart rate and crashes seems to be much different though.

Before I exercise I take either ritalin (10-20mg) or marijuana (.05g to .1g at most in a vaporizer). The cases are somewhat similiar. I will refer to them as the 'medicated' case.

Anyways, without medication typically I can't really exercise. If I get on my exercise bike I just feel very tired. I can get my heart rate upto maybe 110bps average (I'm 35). I feel like a car stuck in first gear. If I start to exert myself more I just start to feel faint and give up after 10-15min.

OTOH if I am medicated I can get on my exercise bike. At the beginning, sometimes I feel good, other times i feel like crap. Usually within 10min though my heart hits a good range ~130bps and I can exercise normally mostly. If its early in the day I can probably maintain that for an hour or more, but if if its in the evening maybe only 30min before I get tired.

110bps non-medicated - I feel like crap... exactly the same as before the exercise. No better, no worse!

130+bps medicated - This depends... As I'm exercising I usually feel awesome. Afterwards though sometimes I feel good... other times I crash but... this may just be the ritalin come down. I haven't figured this out yet.
Sometimes my heart rate stays up at 140-150bps during the workout... these times I believe I may crash more... I need to experiment more on this...

Any comments on this Sue? I certainly feel OI when I try to stand up a lot of the time. But I feel like my case is different than what you describe... or am I just looking at it the wrong way?

Sue Jackson said...

Interesting...that does seem a bit different than most. But having your heart rate go up to 130-150 during exercise certainly sounds like ME/CFS and could cause a crash afterward.

You mention how you feel immediately afterward, but the post-exertional crash characteristic of ME/CFS typically comes later - anywhere from a few hours to a day or two AFTER the exertion. Given the time lag, it is sometimes difficult to see the pattern at first. Before I got diagnosed with ME/CFS and understood the exercise intolerance, I thought my ups and downs were totally random. Try tracking how you feel before, during, and for up to 3 days after exercise (one Japanese study showed that the post-exertion crash peaked 3 days after exertion). So, for me, for instance, if I'm having a good day and take a walk but do too much - stay out too long or raise my heart rate too high - I will still feel great after my walk. But then, several hours later or even the next day, I will suddenly feel like I have the flu - sore throat, flu-like aches, exhaustion, etc. For some people, the response is delayed even more, to 24 -48 hours post-exercise.

So, it takes some careful observation and investigation to really figure out how you react.


Mr Mills said...

Thanks Sue. That's a good idea. I most definitely need to do some more careful observation. For my worst period of illness (>1 year) I had a bad day every day.

These days though I seem to have decent days/weeks followed by bad days/weeks. The bad could be caused by overexertion.... but thus far at least (with medication) I can exercise pretty relatively normally and seem to be able to do this for weeks without worsening symptoms so I'm not even sure how I could find an exercise trigger...

Right now I'm thinking of writing an android app in order to do this for me. Hopefully I remember how to program ;)

Mr Mills said...

Sue just to follow up while I do most certainly have CFS I get little or no post-exertional crash after exercise (these days at least). My heart rate stays around 130bps on my exercise bike. This is while taking ritalin before exercise.
Maybe ritalin is reason I can do it?

Sue Jackson said...

Maybe - who knows? Anyway, glad you can manage it!

NPD Survivor said...

So, which heart rate monitor are you using currently? Am interested in getting one. Thanks for the wonderful information!

Fred said...

Yep I have felt fantastic after exercise but crashed 2 days later and deteriorated...

Sue Jackson said...

Fred -

Yup - that's the way it works for many of us! Makes it hard to see the cause and effect at first.

Sue Jackson said...

I use the HRM shown in the photo at the top of the page and linked at the bottom of the post - a Mio Alpha. Mine is 3 years old now, so the link at the bottom is to the latest model of the Mio Alpha.

Anonymous said...

I'd like to add something here for the benefit of others with ME/CFS. A university in Australia has been doing some serious research into CFS and appear to have had a breakthrough. I say appear because, as they have stated, more research is required but this is promising
This finding might also help to explain oxidative stress as well as PEM

Sue Jackson said...

Their research does sound promising, though it's not quite a grand-breaking as they state in their press release. there has been ample evidence over the course of decades and many studies that ME/CFS is an immune disorder, based on a dysfunctional immune system. If we could just get all these different researchers around the world to work together and build on each other's research!

I did report on another study Griffith did but hadn't seen this one yet, so thanks for the link!

Dan said...

Hello everyone,

Related to possible coagulation problems... You may ask your doctor to look into Antiphospholipid Syndrome (APS). I have both ME and APS. I developed APS before ME, and my family has a long history of autoimmune conditions. My family history of autoimmune conditions explains more about why I acquired APS, not so much about why I acquired ME. I don't know how common it is to have both conditions, or in which order it is most common to acquire them, but the test for APS is simple and usually inexpensive. Some of the symptoms of APS and ME are similar. Anyway, not a whole lot to add here, besides letting you know that it is possible to have ME and a coagulation disorder together. I hope it goes well for you.

Sue Jackson said...

Thank you so much, Dan, for taking the time to leave a comment and explain to all of us about APS. I wasn't familiar with it before, but as I mentioned above, lots of doctors over the decades have linked ME/CFS with coagulation problems in some patients - I wish all the researchers could get together and compare notes!

Thanks again - this seems like important information -


Denise B said...

I am encouraged that you are able to walk and hike some now! Oh, that is my dream! What I'm wondering is, do you think part of your improvement may also come from less stress in your life, less to do as a mother? I know one son is doing much better, and is on his own. I have a daughter who has had special needs since jr. high ages, and also has ME and FM like me now. Having her at home and never having long enough quiet times, and needing to help her out often means I'm not sure if I can pace like I really want to daily. I can't really choose how I use my energy all the time, although I'm good at saying No now when she can get help somewhere else, and she is good at letting me rest more. I wonder if I lived alone, in a clean, quiet place if i would recover more? I guess we all wonder that.

Sue Jackson said...

Hi, Denise!

Thanks for taking the time to leave a comment. While I agree with you on the effects of stress...and I love and cherish any quiet alone time I can manage!! - NO, my improvements were 100% from my treatments. No question. My son has similarly improved with these treatments, and our improvement began while my sons were both still at home.

Treatments for OI, sleep dysfunction, immune dysfunction & more will help to increase your energy, reduce the exercise intolerance and allow you to be active without crashing, and just generally feel much better!!

Here is a summary of the treatments that have worked best for my sons and I over the years - we now function fairly well and live active lives again:

Good luck!


Kim said...

Hi Sue,

Great article,

I am finding it difficult to looking for a heart rate monitor watch (strapless) that ticks all the boxes you mentioned: -

Although there are now many different kinds of wearable devices that can measure your heart rate, there are a couple of things to look for that you'll need specifically for ME/CFS. You want a heart rate monitor that continuously monitors your heart rate, giving a constant read-out. The kinds of devices that require you to push a button to check your heart rate aren't adequate for us. A large read-out that you can easily see is best. You also want to make sure that you can set audible alarms for heart rate that are custom to you. Some devices may just calculate your limits based on your age, but with ME/CFS, we are using it differently than that. You will set your upper limit to whatever your anaerobic threshold (AT) is, according to the formula above, and you want an audible alarm to inform you immediately if you hit that limit. All models can link to a smart phone or computer, so you can see your data.

I have been very happy with my Alpha Mio heart rate monitor. There are, of course, now plenty of fitness trackers available, like Fitbit, that measure heart rate, though I find their HR read-outs quite small and hard to see while you are moving around, and they are designed for athletes and active people, with different settings for different sports and activities. They do, however, have additional features like sleep tracking, so you can compare models and brands and decide for yourself.

Is the Alpha Mio HR monitor a strapless watch type please and the newer one you wear the Polar what model is that also? The link in the article no longer works.
It's for my 16 yo daughter who has ME/CFS and POTS too..we just can't seem it get this watch HR monitor business sorted..

Thanks Sue


Sue Jackson said...

Hi, Kim -

That link no longer works because the Mio Alpha is no longer available :( Not sure if the company went out of business or what, but you can only find them on eBay and other resale sites (sometimes Amazon has some from other sellers). And I believe all the Polar models have a chest strap, which many people like, but I found uncomfortable, inconvenient, and less accurate.

So, I recently got my son a Garmin Vivosmart 4 fitness tracker. I looked at a bunch of different models, read all the info on this one, and even called Garmin to confirm you could set your own upper HR limit and set it to always show HR (it takes a few steps but it can be done).

In asking others in support groups, I heard lots of people say that Smart Watches do what we need, too (like Apple Watch, Samsung Galaxy, etc), but those are typically $300-$500. The Garmin Vivosmart 4 was just $100.

Hope that helps - let me know how it goes!

And are you in our Parents group on Facebook? You'd fit right in!


Sue Jackson said...

Kim -

Thanks for the reminder - I just updated the post to include links to the different HR monitor options so it's easier to check them out and compare to see what will work best for you :)


Angie Y. said...

Hi Sue,
Along with CFS, i have Graves' disease which caused the Thyroid Eye Disease. I have just started an antibody medicine for the eye disease which has been extremely effective so far! The problem is the side effects are quite intense and it feels like it makes the CFS worse. (Before the eye medicine, i had just started being able to dance and sweat again without crashing! :)) The doctor has recommended a Myers cocktail to go with the eye medicine to help with the side effects...but i just thought i would ask you if you had any other ideas on how to cope with this medicine that is reversing my eye disease but really heavy on my body?? Thanks so much, Angie

Sue Jackson said...

Hi, Angie -

Sorry for the delay in getting back to you - I got SO FAR behind with Thanksgiving, family, and crises the past two weeks.

So, this is a VERY complicated issue. You say the medicine for the eye disease is an antibody medicine (and I looked it up to learn more). Graves is an autoimmune disorder, meaning the immune system is overreacting and attacking the body. ME/CFS is not strictly autoimmune but a combination, where parts of our immune system overreact, while other parts underreact. So, generally, meds used to treat autoimmune disease suppress the immune system, but this can cause adverse effects for us, since the parts of our immune system are already suppressed. This antibody treatment is working that way - it is better than older steroid treatments that shut down the whole immune system, but it seems that the part of the immune system it is blocking might be a part that is underactive already in ME/CFS - thereby making your ME/CFS symptoms worse.

Myer's Cocktail is just a mix of vitamins and magnesium in an IV - my son and I do use them sometimes, but it is highly unlikely to have much effect on your immune system (which is causing your ME/CFS symptoms). You can try and see what happens - you are likely to get a temporary boost (a day or two) - and it won't hurt.

A better option - and perhaps even a substitute for the med that is causing the trouble - is to help to normalize your immune system (not suppress it and not boosting it but balancing it). That would help both ME/CFS and Graves. We have found 3 approaches that have all helped us to normalize our immune systems and reduce the kinds of symptoms you mentioned - they are all inexpensive and readily available. Some don't even require a doctor's help. More info and links here:

I would start with inosine, as the cheapest and easiest (no Rx), though be sure to follow the dosing guidelines I lay out. Glutathione is also absolutely essential for immune system function (as well as energy, detox, and more) - there are lots of ways to increase it (see that link above), but if your doctor is offering a Myer's Cocktail IV, ask if you can get a bag of glutathione, instead of or in addition to the vitamins. That's what we do - but we also take glutathione nasal spray every day at home. It's all explained in the links.

I know this is complicated, but you have a very complex set of diagnoses! Take a look and let me know if you have any questions.


(Just a reminder that I'm not a medical professional - just sharing our own experiences :) )

Lucy said...

This is such a brilliant post Sue, thank you. Pacing and trying to prevent crashes is something that no matter how much time passes I still struggle with. Measuring heart rate to be able to identify which specific activities are more demanding for me will be so useful for allowing me to make more progress, prevent flares and schedule my activities better. Thank you again.

Sue Jackson said...

I hear you, Lucy!! Even after 20 years with ME/CFS, pacing is still the toughest part. Tracking HR really helps. I've also recently started counting steps (with my phone) - just another way to measure how much is too much for me.

I wrote about it here on the blog:

And I also made a video about both approaches:

So glad you found this helpful! Good luck and let me know how it goes -


Grace Buchanan said...

Sue, thank you so much for sharing your HRM experience. I read this post several times, coming to terms with the severity of my disease, and feeling innoculated with hope. During the two days when I used my HRM recently (before it broke), I learned so much! One day, as I rested in bed, my heart rated slowed down to 55 bpm, which is the lowest I've seen for me. I felt exhausted, but thought that such a slow pulse might indicate that I could push myself. I LOVE pushing myself to do hard things. So, I lifted weights while lying down, and then sitting, and my pulse stayed down in the 70s. Yay!

Later that day, I felt well enough to plant a couple large shrubs that we had gotten from a nearby nursery. I was delighted to see how well my heart rate stayed below 100 bpm as I worked very slowly and with a lot of support from my sweetheart. When I started to get foggy-brained, the slightest effort shot my heart rate up over 160! I went right back to bed.

I appreciate you sharing your story because it helps me to believe in the reality of my own experience. I am working on identifying my AT so I might be able to avoid PEM. Around 10 years ago, a psychotherapist urged me to set a timer to periodically check in with myself. Each time it rang, I felt annoyed by the interruption. Now that my symptoms have become more severe, and now that I read bits of your story, I welcome the alarms. Now they are clearly self-care. Now they will teach me to live within my limits. I'm so glad that my new Garmin watch is still expected to arrive tomorrow!

Thank you for giving me hope.