Post Exertional Malaise

A notable worsening of symptoms brought on by minimal physical or mental exertion.

In the "Characterising Long Covid" survey participants were asked whether they had experienced “worsening or relapse of symptoms after physical or mental activity during COVID-19 recovery” ie post-exertional malaise (PEM). 89.1% of participants reported experiencing either physical or mental PEM.

Of the respondents who experience PEM triggered by physical exertion, almost 50% experienced it the following day, 42.5% experienced it the same day, and 28.7% experienced PEM immediately after

Of the respondents who experienced PEM triggered by mental exertion, 42.2% experienced it the same day, and 31.4% experienced it immediately after. For some respondents the time PEM started varied. A high number of the respondents with PEM (68.3%) indicated that the PEM lasted for a few days. For physical exertion, the mean severity rating was 7.71, and for mental exertion, the mean severity rating was 5.47.

PEM can be caused by physical as well as mental exertion. For example:

  • reading a book

  • watching television

  • having a conversation

  • standing up for long periods

  • trying to concentrate on a zoom call

  • having an argument

  • sensory overload - loud noises, bright lights

  • getting out of bed, cleaning teeth, having a shower

  • trying to do a shopping list

  • emotional stress, premenstrual stress

The activity for some can be very minimal and yet still cause a considerable impact on energy levels and symptoms.

Symptoms range from a post-exertional flu like feeling to cognitive impairments (brain fog)

myalgia (muscle pain), dizziness on standing (orthostatic intolerance), sleep difficulties and IBS type symptoms, among many others.

The onset of PEM is frequently delayed with many reporting the height of their symptom flare-up, two or several days after the initial trigger.

Recovery from PEM is often prolonged, lasting days or sometimes weeks to months, patients refer to these post-exertional setbacks, in the Long Covid community they are often known as ‘relapses’

PEM is considered to be the hallmark symptom of ME/CFS and it is for this reason that many long haulers have linked themselves to the ME community in the search for answers.

While in most diseases patients experience symptom relief after exercise the opposite is true for ME/CFS patients for whom even minimal exertion can cause a symptom flare-up.

In " Characterizing Long Covid" a total of 2454 (65.2%) respondents were experiencing symptoms for at least 6 months. For this group, the top remaining symptoms after 6 months were fatigue (80.0%), post-exertional malaise (73.3%), and cognitive dysfunction (58.4%)


This is a self management technique rather than a treatment as a way to cope with the impact of PEM.

It balances activity ( physical, mental and emotional) and rest to prevent post- exertional malaise.

Pacing is not a "one size fits all" approach and may need to be adjusted on a day to day basis. It has long term benefits of stability in symptoms, relapse prevention, gives a feeling of control, learning coping strategies and establishes a starting point for improvement and/or recovery.

In the " Characterising Long Covid" study pacing was found to be the most highly rated management approach and was significantly helpful in 25%.

Helpful literature on pacing

Pacing for people with ME

How I Use Pacing to Manage ME/CFS

Nice backtracks on graded exercise therapy and CBT in draft revision of CFS guideline

Purely Pacing

Rose Cottage Doc IG post "Pacing Yourself"

Activity Management -Pacing

The Spoon Theory written by Christine Miserandino

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