Post-exertional malaise is a poor diagnostic indicator, the sensitivity and specificity are quite low. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7988339/ ht

Post-exertional malaise is a poor diagnostic indicator, the sensitivity and specificity are quite low. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7988339/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7988339/ First problem, I do not have ME/CFS, let's use the Maes et al (2012) scale. 0-5 scale, 5 being the worst. "1 means mild exacerbations of fatigue/pain/neurocognitive symptoms following exercise (either cognitive or physical)" Yep, after a longer, harder than normal bike ride I'm quite fatigued, in quite a bit of pain (bad back, knee, shoulder), and can't think particularly well. "2 means moderate exacerbations of symptoms following exercise; 3 means severe, incapacitating exacerbations lasting less than 24 hours;" Accurately describes what happens when I do HIIT style intervals that exceed my work capacity, or what it's extremely hot outside. Dreadfully exhausted, usually have to nap, or lay on the couch, every muscle hurts, extremely sore, difficult & painful to move for 24-72 hours. I'm not saying ME/CFS does not exist, this is just a terrible indicator. The worst part is making it so specific obscures the large body of existing research that would provide tools for treatment protocols here, eg work capacity in athletes.