Monitoring Heartrate to Help Manage Your Illness
What It Is
Heart rate is the number of times your heart beats per minute.
Why It Matters
People with ME/CFS and Long COVID often have abnormal heart rate patterns that may cause palpitations, chest pain, shortness of breath, dizziness, fainting, fatigue, and cognitive impairment.
Most people with ME/CFS or Long COVID find that:
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They have a much higher chance of crashing if they exceed a certain heart rate (their Anaerobic Threshold or AT, which is different for everyone); and
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On days they have less energy, their heart rate tends to spike more or be higher, including (often) first thing in the morning.
Heart rate is considered by many patients to be one of the best immediate warning signs to stop, recline, rest, or take it easy.
How to Use It
With a bit of experimentation, you will likely find your own times, circumstances and ways to measure heartrate that will give you the best information. Some common useful approaches (that serve slightly different purposes) include:
Measuring your heartrate every day in the morning
Purpose: For some people, your resting heart rate at the start of the day can help predict how your symptoms will be that day and what energy you will have. This will help you determine when to take it extra easy and what days you may have a little more in your “energy envelope.”
For many, a morning measurement of Heart Rate Variability (HRT) is an even stronger marker of how you are doing. See here.
Measuring your heartrate throughout the day and in different situations and positions
Purpose: Identifying triggers that make symptoms worse, and behaviours that may help you rest effectively. Example:
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For some people, sitting is good rest, while for others, they must fully recline to get their heartrate to slow.
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Measuring your heartrate during and after exertion
Purpose: Determining if there are physical, mental or cognitive activities that can be tolerated better (or at all) if the heart rate stays under a certain threshold.
Example:
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Some people can walk for short periods (or even longer) if they carefully keep their heart rate under a certain level (the level that works will be different for everyone).
How You Measure It
Basic Heartrate
Heart Rate is measured as number of beats per minute.
There are many ways to measure your heartrate, including manually (on your wrist, neck, foot, crook of the elbow) and with various heart rate monitors (chest band, smart-watch or other wrist monitor, ring monitor, smart phone).
Your Anaerobic Threshold (AT)
Your AT is the heart rate at which your cells run out of oxygen (see more here).
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Athletes have a high AT (can exercise hard before hitting their AT heart rate).
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People with heart disease, ME/CFS or Long COVID often have a much lower AT (50-60% that of a healthy person).
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When you exceed your AT (go over the AT heart rate for you), you will likely feel exhausted, have worsening other symptoms (such as pain, headaches, dizziness), experience an immediate crash, or trigger PEM (Post-Exertional Malaise, or a significant worsening of symptoms within the next 12-48 hours).
To find your AT
1. Choose a heartrate monitor
See the section correct “Devices and Apps” below or manually measure your heartrate throughout the day.
2. Estimate your AT
For people with ME/CFS or Long-COVID, estimate your AT using this formula:
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Men
(220 – age) * 0.6 = estimated AT
(Or if more ill, use 0.5 instead of 0.6)
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Women
(220 – (age * .88)) * 0.6 = estimated AT
(Or if more ill, use 0.5 instead of 0.6)
3. Verify your AT
Be cautious as even minimal exertion can cause worsening of symptoms or longer-term harm.
Find the heart rate where, if you stay below it, you can usually avoid PEM. This is your AT.
Start by staying well under your estimated AT.
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If you stay below your AT and never crash from over-exertion, you may consider carefully experimenting with going higher than your estimated AT by a few beats per minute (bpm).
Important Note: Your AT may change over time and with any change in the severity of your illness.
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Important Note: Things other than physical exertion can also cause crashes or PEM. You may need complete rest and no physical exertion at all if you are also expending mental, social or emotional effort.
What to Think about for Devices and Apps
There are many heart rate monitor options, from chest straps that only measure heart rate to wearable devices with many functions, like Fitbits and smart watches or smart rings (see more here). A few features that may help:
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A customizable alarm for heart rate – Many devices let you customize an alarm to tell you when you hit a certain heartrate
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A continuous, visible heart rate read-out – Best if you can see your heart rate without having to push a button.
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A device that is comfortable – Many users prefer wrist devices. For some people, chest straps are uncomfortable and awkward to put on and wear.
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Extra features – many heart rate monitors sync with or download data to your smart phone or computer. Some include stopwatches, calorie counters, step counters, heart rate variability measures, and more.
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