More research needed into the lack of recovery time in PEM
The journal Science Norway looks at the key characteristic in ME/CFS of PEM, which can also be found in some people with Long COVID and Fibromyalgia.
It highlights that a type of test called repeated CPET measurements can precisely show how a session of physical activity affects a person’s condition afterwards – they perform worse and the lactic acid in their muscles builds up faster, they have poorer pain regulation and changes in the immune system and interaction with intestinal flora.
One study showed that strenuous mental tasks led to changes in the brains of ME/CFS patients that were not found in healthy people. The changes could correspond with the patients’ experiences of having an impaired ability to think and concentrate after the activity.
No research has been done into whether the same mechanisms can trigger PEM following social or mental exertion as from physical activity. It is not known if the same causes underlie fatigue and symptoms in the muscles and general fatigue throughout the system.
Researchers do not know if this is due to the same mechanisms as exercise-induced PEM. A 2016 study suggested that these might be different phenomena.
Prof Nina Vøllestad believes that existing research may provide a distorted picture, because the patients in the studies had to be able to complete a physical training session.
This probably means that the participants who were selected either had a lighter disease burden or were in a recovery phase, according to Prof Vøllestad and colleague Prof Emerita Anne Marit Mengshoel.
“When we engage in demanding activity, we get tired and need to recover,” Vøllestad says.
Vøllestad sees interesting similarities between PEM in ME/CFS patients and the symptoms of athletes with overtraining syndrome. Overtraining is where the athlete does not get enough recovery time between training sessions over a long period.
“They’re not back to baseline before they start again. So, they wear themselves out, and it can take half a year to recover. The symptoms are very similar to ME/CFS,” says Vøllestad.
The question is: Why don’t ME/CFS patients recover normally?
But here, there are few answers.
“We lack research on biological changes during the recovery phase,” she says.
