ME Awareness week- Post Exertional Malaise

This week is ME awareness week. ME (also known as CFS) is generally categorised as fatigue lasting more than three months and not explained by another diagnosis. But it’s so much more than feeling tired, so this week I will be concentrating on a different symptom each day and how they affect me.

Today I’m concentrating on post-exertional malaise (PEM). It’s the key diagnostic feature of ME/CFS and describes the way in which symptoms worsen after activity. 

This has been measured. People with ME were tested using two-day cardiopulmonary exercise tests. They perform the same activity 24-hour is apart and a significant decrease in performance was measured on the second day.

The effect of PEM is usually delayed so I can do an activity and feel fine. But then later that day, the next day or even two days later I’ll experience an increase in symptoms and crash. This makes it really hard to gauge what activity is going to cause a problem. An activity I can do one day without issue may trigger a crash on a different day. Quite often I experience what I call slow crashes. This happens when don’t overdo it so much that I crash from one days activity, but instead my symptoms slowly worsen each day until I reach critical point and crash. PEM also means it is much longer for me to recover from activity. Usually, for each busy day that I have I need about three days to recover. This is just a rough estimate and it can take much longer.

There is no treatment for PEM. All we can do is try to avoid triggering it by pacing. The current guidelines for pacing are that your heart rate shouldn’t go above 15 bpm over your resting heart rate. For me this means my heartrate should stay under 85 bpm. This is extremely difficult to do. Ideally, I’d have a heart rate monitor that would alarm when I reach this limit. However, the ones on the market are aimed at fitness enthusiasts rather than medical devices. So, it relies on me constantly checking my heart rate. Some days just sitting still my heart rate is above this. Other days I can walk upstairs and still be under that limit. Most days I spend at least two hours above 85 bpm, which means I’m constantly running the risk of crashing.

Once PEM is triggered all we can do is rest. But it’s often a vicious circle. Because while we are experiencing a crash the threshold for causing PEM is much lower. So for example, on a good day showering is no issue for me, but during a crash it will cause PEM. So just doing basic personal care tasks, like going to the toilet, washing, preparing food and eating, prolong the crash.

Unfortunately despite this symptom being well documented exercise is often still prescribed for people with ME. My GP still believes that I should be exercising. I have tried just going for a short walk everyday, but this just led to a crash.  Thankfully, the guidelines treatment in the UK are being updated to reflect that exercise is not an appropriate treatment. However, this will take a long time to filter down to treatment of patients.