Introduction Post-exertional malaise (PEM), sometimes referred to as post-exertional symptom exacerbation (PESE) or post-exertional neuroimmune exhaustion (PENE), is a worsening of symptoms that occurs after minimal exertion. It is the hallmark symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and common in long COVID and fibromyalgia. PEM is often severe enough to be disabling, and is… Read More