For people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), even a minor exertion can lead to post-exertional malaise (PEM). PEM involves a disabling constellation of unusual symptoms and signs. It can last for weeks, months...even forever.

We have plenty of data from various fields of biology and medicine that describe the complex pathophysiology of PEM. However, outdated ideas like "effort preference" and "deconditioning" are still being used to misrepresent this condition.

I am proud to have led an international team of ME/CFS experts in responding to an article published on the largest NIH intramural study of ME/CFS to date. It was published in the journal 'Nature' today.

Here are the key points:

🔑 PEM is biological, not behavioral. It’s not about motivation or avoidance. It’s a measurable physiological response.

🔑 Testing in the study falls short. One-day cardiopulmonary exercise tests fail to capture recovery failure. Two-day CPET and other physiological tests can reveal the true impact of exertion.

🔑 Misinterpretation harms patients. Suggesting ME/CFS is about effort preference risks blaming patients instead of addressing the underlying pathology.

Better science means better care. Accurate testing and understanding are essential for diagnosis, research, and effective treatment.

ME/CFS isn’t about doing less by choice. It’s about the body’s inability to recover. It’s time to shift the narrative from motivation to biology.