I am in about half a dozen online support groups in which heart rate pacing for ME is a topic. Folks hear about it and want to try it out as a tool. Then they get confused and frustrated by the devices before they ever get to really working with the tool.

Two photos of a sports watch
Two photos of a Polar A370 watch on Rebecca’s arm.
In the top photo, the heart rate reads 61 in blue text. A written caption says “sitting.”
In the bottom photo the heart rate on the watch read 108 in red. The added caption reads, “sitting sealing envelopes.”

I used to be a trainer in my professional life, among other hats. While my style wasn’t for everyone, I found that folks really appreciated understanding the big picture.

Heart rate pacing is one of several pacing tools that ME patients may want to use to limit their crashes and help improve their quality of life. Some practitioners find that over time their energy envelope increases as well. Other pacing tools include keeping logs of activities and their effects, scheduled and enforced rest periods, or just a vague sense of when you should stop and rest.

Heart rate pacing is more objective, which I really appreciate. It is based around the research that ME patients have a wildly reduced anaerobic threshold compared to normal people. That is part of the mechanism that causes post-exertional malaise, usually referred to as PEM. Those who have the opportunity to complete a 2-day CPET evaluation have access to knowing their exact anaerobic threshold. Others take educated guesses, and tweak their numbers through experimentation.

The goal with heart rate pacing, is to minimize the amount of time over your anaerobic threshold as much as possible. And when you do exceed, to do so for less than 2 minutes if possible, followed by a period of recovery rest. In order to do this effectively, you need to know when you’ve exceed your anaerobic threshold. While you can learn some valuable thing from using an activity watch that has continuous heart rate monitoring, they require you to look at the display to know what’s going on with your heart rate. This is impractical in daily life – the activities you do that could increase your heart rate too much usually demand your attention. And your watch might or might not have a continuously lit display, so you might have to stop what you’re doing to turn on the light to read the number to go back to what you are doing.  It’s better than nothing, but it isn’t practical.

What you really want is a device that will alert you to when you’re close to, or crossing your warning number.

There is no device that just does this. You can’t just buy a watch and say hey, let me know when my HR is too high. So we do something absurd: in order to restrict our activity, we buy a sports watch for high performance athletes who are trying to *increase* their training activity. Then we bend it to our purposes.

Athletes want to customize their workouts and calibrate the amount of time they spend in different heart rate zones, depending on their training zones.  We do to! Except our training is for life. And our goal is to stay in the lowest ranges possible. Hell, I give myself a mental gold star for every “inactivity badge” I can earn in the course of a day.

So, what we have to do is approach each day as a workout.

I use Polar devices, so my knowledge is specifically about them. In Polar Flow, there is an option to customize workout activities. We pick one, and use that as our daily activity. I use “other indoor.” Within that activity, we can program the heart rate ranges that make sense for our impaired systems, and turn on the alerts (detailed  instructions for this are here).

Screenshot of heart rate data
Screenshot of the Polar Flow app, showing the details of a specific workout session.
Duration is 15:38:17
Average HR 71 bpm
1050 kcal burned
HR min 46 bpm
HR max 134 bpm
Far burn % of calories is 76%
Screenshot of a workout session from the Polar Flow app
Screenshot of a workout session from the Polar Flow app. It focuses on a day-long heart rate graph against a colored coded backdrop of different heart rate zones, and a chart showing the amount of time spent in each heart rate zone.

Each day when you want to activate your alert and data collection, you start that workout activity on your watch. When you are done, you end your training session.

Throughout your training session, your vibration alert will activate at whatever HR number you set. In my case, it’s 86 bpm. Throughout the day you can see what zones you are in. Depending on the model device you have, you may have access to additional features, like how long you’ve spent in each heart rate zone.

This will offer you potentially surprising information and insights into exactly what kind of activity is a problem for you. I now know, for example, that any kind of repetitive motion with my arms is a problem. Before i had a tracking device, I wouldn’t have thought anything about doing simple things while seated.

When your session is done for the day, there is likely an option to synch your data to a phone or computer. There is often much more data available for analysis at the end of the day, and I find this very useful.

Each day I look at and record my average heart rate, maximum rate, lowest rate, time I spent over my AT, and the time I spent over my ideal pacing number (which is lower than my AT). I can see a heart rate graph and see when my heart rate was particularly dynamic. It also helps me understand how well my POTS is managed.