Resia Pretorius

Why this new PEM paper matters One of the most disabling features of Long COVID and ME/CFS is post-exertional malaise (PEM) — the “crash” that can happen after doing something that would once have been completely ordinary. For years, PEM has largely been described by what people feel: overwhelming exhaustion, brain fog, pain, flu-like symptoms and worsening of other symptoms after physical or mental exertion. This paper asks us to look at it differently. Imagine the body as a collection of interconnected systems. When a healthy person exercises, those systems are temporarily pushed away from their normal state. Heart rate changes. Metabolism changes. Muscles use more oxygen and energy. Hormones, blood vessels and the nervous system all respond. Then something important happens: The body resets. The different systems gradually return towards their normal state. The researchers propose that PEM may involve something going wrong with that recovery process. Instead of all those systems coordinating their return to normal, some may recover too slowly, some may remain abnormal and others may move in completely different directions. In other words, the PEM “crash” might be what it feels like when multiple physiological systems fail to properly reset after exertion. That’s potentially a very important idea because it changes what scientists should measure. Rather than simply asking someone how they feel after exercise—or taking one blood sample—they could follow people for hours or days afterwards and watch how metabolism, circulation, the autonomic nervous system, immune activity and other systems change over time. And different people may have different patterns. That could eventually help researchers identify different biological types of PEM and, importantly, treatments aimed at whatever part of the recovery process has gone wrong. This paper doesn’t prove this mechanism, and it hasn’t discovered a treatment or diagnostic test. It’s a scientific perspective proposing a framework that now needs to be tested. But I think the question it asks is an important one: Perhaps PEM isn’t simply about what exercise does to the body. Perhaps it’s about what the body fails to do afterwards. And if researchers can work out exactly where that recovery process breaks down, we may finally get much closer to understanding one of the defining features of Long COVID and ME/CFS. AI disclosure: I used AI to help research and draft this post. I reviewed and approved the final content.