Under Pressure – finding better ways to monitor my body

This time last year I bought myself a fitness tracker watch with heart rate and blood pressure functions. I haven’t compared the bp measure with a properly calibrated one yet, so the actual numbers may well be wrong (I know they’re within the right ballpark though), but it is internally consistent, which is all I need.

So for a year now I’ve been using it to monitor and manage my activity and my body. It’s been really helpful.
I’ve had activity trackers before, and worked out that my limit for activity is around the 3,000 step mark so I try to be around 2,000. But knowing this only meant I could prevent that particular kind of PEM related crash. I was still getting terrible symptoms from things like heat/cold, standing, emotional exhaustion, mental fatigue, noise etc with no easy way to track or monitor them. This would result in reaching a collapsing point – the kind I described here, for example.

After watching this talk, part of the 3rd annual symposium on the molecular basis of ME/CFS in 2019, I decided I wanted to see how useful I found the biometrics available in the wearables and phone apps I could access.

Initially I used phone/camera based metrics and apps, like the heat rate and heart rate variability tests I could get on Samsung health and [app]. I found the stress tests most useful, but limited they would accurately tell me if I was verging on our in the middle of a fatigue induced anxiety attack, or if I PEM (which I could then show someone else). Sometimes the stress test would top out well before my body did.

Having an objective measure of how you’re feeling that can be shown to others to prove it’s real can be helpful, but I needed to stop getting to the point where I had physical collapses or panic attacks, or even headaches and flu symptoms.  I needed a way to identify that my activity now was going to cause a crash later.

I decided to try blood pressure monitoring, since I knew I could get it on a wearable, but getting one was financially restrictive.

Around the New Year (new me) period, GrabOne started running deals on fitness trackers and I was able to buy myself one that had activity, sleep, heart rate, blood oxygen, and blood pressure monitoring for only $39 of Xmas money. It arrived mid February.

Initially, I thought it was measuring low, but then I remembered how low my BP was when I was in hospital in 2019, and it seemed about right. Most of the time, if I’m doing ok, it will sit around 99/65, or even a little lower.

I did some reading on what the different numbers meant and their relationship. Then I got to paying attention to what they might be telling me about me.

What I learnt

It didn’t take long to notice a couple of key relationships between my blood pressure and my ME.

Image shows blood pressure screen from fitness app. BP is 91/65, blood oxygen is 99%, and degree of fatigue is “mild fatigue”.

1) When I am reaching my limit for the moment, or if I have gone over it, my BP will increase. Both numbers will increase together (a typical example would be 115/70).

2) If my blood volume is dropping and I need more electrolytes (or I need to mix them up less dilute) the systolic (top) pressure would increase but the diastolic (bottom) would lag (e.g. I might get a reading of 110/60). If I’m getting dehydrated enough to trigger a crash, the difference will approach 50 mmHg.

This has been really helpful. I can now differentiate between feeling tired because I’m using too much energy and feeling tired because my kidneys are forgetting to switch off and I can behave appropriately to prevent a crash.

Interestingly, it seems to be in keeping with the findings of the Massey University exercise trials (you can see a video talking about their research here). They found that while our BP is usually low at rest, it can get dangerously high in exercise. This means monitoring BP during exertion is important for managing PEM. I really want to have a play with this, but I worry about pushing myself too hard again while I work out my best exercise levels.

I also noticed something with the sleep and heart rate monitoring. I read somewhere (I forget where now) that when a healthy person sleeps their pulse rate will drop noticeably from their waking resting heart rate (so even if the person hasn’t moved in hours, you can tell of they are asleep by taking their pulse), but in people with ME they stay about the same.

Image shows screenshot of heart rate monitor graph. Graph line is all over the place between 86 and 51 bpm over a 24 hour period. There’s no recognisable period of sleep where the heart rate drops or is even steady.

My resting heart rate is already pretty good, at around 60-70 bpm (depending on whether I’m dealing with a crash or low blood volume etc), but most nights it doesn’t get below 57 bpm, if it drops at all, and sometimes stats around 65. However, on the rare morning when I wake up feeling really good and rested, I notice that my heart rate usually dropped down as low as 55 or even 50bpm when I was sleeping. This seems to be a far better indication of the quality of my rest and sleep than the sleep tracker, as even nights I appear to have had good quality sleep with long sleep cycles (it’s common for me to has 30 minute sleep cycles rather than the 90 minutes they should be), I’m still not getting good quality rest.

The result of this.

For almost a year, I’ve managed to keep my energy levels pretty consistent. I haven’t had so much of the extreme swinging between active and crashing. My husband says he has noticed it, and that my moods are more stable too (far fewer days of depression and grumpy toddler me). I overdid things a bit during lockdown, in an attempt to keep a 4 year old sane, but I knew that I was doing it and what would happen. I’ve had only a a couple of days of reaching collapse, usually unavoidably (Xmas day being a big one). I have been able to find a happy medium of activity that lets me get out of the house or get a few things done, but doesn’t put me in bed for days.

Where to from here?

Ultimately, I would like to be able to find patterns that I can use to manage my illness better so I can return to work, full time or part time, and exercise again.

First up, I need to get better at actually taking the readings regularly, or I need a device that will take my blood pressure at regular intervals and give me an alert if it rises in the ways I described.

I also need to work out what I do that means some nights my heart rate behaves normally and then try to make a habit of doing that.

A full fitness test would be nice, so I can find my anaerobic threshold and add that into my management strategy.

I’d really love to try monitoring my skin temperature too, as I know this is a factor, and one I still can’t find the edges of. When is cold ok? How cold is too cold?

I also want to monitor my blood glucose, as I think that this may be making a difference too. I have a bad habit of forgetting to eat, or I eat junk food and cause a spike. I’d like to see how these affect my energy.

Unfortunately, most of this would require flasher tech than I can afford, so it’s not likely to happen in the foreseeable future.

What biometrics have you found helpful?

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