Post-exertional malaise and the myth of cardiac deconditioning: rethinking the pathophysiology of long covid ‼️Important and HIGH TIME this got addressed! ➡️This excellent international paper scientifically argues that heart-related issues seen in long COVID (like problems with blood flow/preload, inflammation, scarring, or poor oxygen use by muscles) aren't mainly explained by simple deconditioning from bed rest or inactivity. Instead, deeper problems are likely involved, such as issues with mitochondria (the cell's energy factories), blood vessel/endothelial dysfunction, autoimmunity, or other post-viral effects. ➡️The IMPORTANT takeaways for patients and colleagues: 1. Long COVID is NOT just "being out of shape" or simple deconditioning from illness/inactivity. The idea that heart and exercise problems in long COVID are mostly reversible deconditioning is a myth, it fails to explain what doctors actually see. 2. Post-exertional malaise (PEM) is the REAL hallmark, hitting ~80% of long COVID patients hard. Even mild activity (physical or mental) triggers a delayed, brutal crash: massive fatigue, pain, brain fog, etc., that drags on for days, weeks, or longer, sometimes permanently worsening your baseline. This is not what happens in normal deconditioning. 3. Heart issues in long COVID go way beyond deconditioning. We're talking real damage: myocardial scarring, inflammation, "leaky" blood vessels, preload failure (heart doesn't fill properly), mitochondrial dysfunction, endothelial problems, autoimmunity, and poor oxygen use in muscles. Deconditioning alone cannot account for these, especially the weird preload issues seen on invasive testing. 4.Pushing graded exercise therapy is DANGEROUS for people with PEM. Traditional "build up gradually" programs are contraindicated — they risk serious harm, crashes, and permanent setbacks. The WHO already warns against this for anyone with PEM. 5. One-size-fits-all exercise advice is reckless. - Stop assuming long COVID = deconditioning. - Screen EVERY patient for PEM first (using tools like questionnaires). - Treatment must be highly personalized: pacing (staying strictly within your energy limits, often with heart rate monitoring), light tolerated activity, breathing work, avoiding prolonged bed rest, and sometimes meds for related issues like POTS. ‼️Long COVID's exercise intolerance and cardiac changes are largely independent of deconditioning. Ignoring PEM and pushing standard rehab can actively harm patients. Doctors and patients need to ditch the outdated "just get fitter" mindset and adopt physiology-guided, PEM-safe strategies, or risk making things much worse. bjsm.bmj.com/content/early/2…