What is
PEM?
Post-Exertional Malaise
PEM is a delayed crash, occurring hours or even days after minimal exertion - physical, cognitive, or emotional - and is characterised by a worsening of multiple systems, not just fatigue.
The hallmark of PEM is that it is out of proportion to the activity that caused it and can take days or weeks to resolve. It reflects intrinsic biological dysfunction, rather than simple deconditioning.
Rest does not immediately reverse it, and “pushing through” often leads to a deeper, more prolonged crash.
What Causes
PEM?
Vascular Dysfunction
Capillaries deliver oxygen & nutrients and remove the waste for all the cells in our body.
Research has found that people with Long COVID have reduced capillary density and thicker capillary membranes, which may make oxygen delivery less efficient.
Mitochondrial and
vascular dysfunction
Microvascular Dysfunction
Control
Long COVID
A Slaghekke et al.
Mitochondrial Dysfunction
Mitochondria are the powerhouses of our cells, producing most of our body’s energy.
Research has found that people with Long COVID have reduced capillary density and thicker capillary membranes, which may make oxygen delivery less efficient.
Until there are better treatments, one way to describe PEM is that it is like sunburn. If you have bad sunburn you can’t fix it, but you can treat the pain and symptoms until it heals.
Rolling
PEM
Rolling PEM is when your body doesn’t get time to recover before the next exertion.
This study measured the body’s chemical messengers following exercise.
The bodies responded immediately even though the patients did not experience symptoms until later.
Further exercise would stack the chemical messengers causing further illness.