You crashed. Here is what to do in the next 72 hours. Post-exertional malaise is not random punishment. It is a predictable biological event with a predictable recovery arc, and how you handle the first three days decides how deep the hole goes.
2/6 Phase 1: First 24 hours. Horizontal rest. Not couch rest. Horizontal, legs level with the heart. Minimize sensory input. No screens if possible, no conversations requiring effort, no decisions. Salt and electrolytes, sipped slowly.
3/6 The goal in hours 0-24 is not recovery. It is stopping the energy hemorrhage. Every upright minute drains the mitochondria you need to rebuild. Treat this window the way you would treat any acute flare: the less you demand, the faster the cells stabilize.
Endothelial repair is slow, but it is measurable. Three markers shift weeks to months before your exercise tolerance returns. The biology heals before you feel the healing, and there are tests that can track it while you still feel sick.
2/6 Nitric oxide availability. The endothelium produces nitric oxide to dilate vessels and regulate flow. In endothelial injury, production drops. Flow-mediated dilation on brachial ultrasound shows the trend as cells recover. Objective, noninvasive, repeatable.
3/6 Glycocalyx thickness. A gel layer coating the inside of your blood vessels, protecting the endothelium and regulating permeability. COVID degrades it. Sublingual capillary imaging can visualize perfusion improving as the layer regenerates.
The first hour out of bed sets the tone for the entire day in dysautonomia. Four things that worsen morning crashes, and three that help. If your worst hours land before 10 AM, the trigger is usually something you did in the first 30 minutes awake.
2/6 Caffeine on an empty stomach. Coffee triggers a cortisol spike and vasoconstriction. On already low blood volume and impaired autonomic regulation, the spike is followed by a crash hitting harder than the fatigue you woke up with.
3/6 Hot shower first thing. Heat dilates blood vessels. Blood pools in your legs. Your autonomic system cannot compensate, and heart rate climbs trying to maintain perfusion to your brain. The lightheadedness after a morning shower is not low blood sugar.
Three MCAS tests your allergist is probably not ordering. And what each one tells you about your specific activation pattern.
2/6 Serum tryptase, timed to a flare. Tryptase is released when mast cells degranulate. A blood draw during a flare captures the spike. Many allergists order it once, at a random time, and call it normal. The timing is the test.
3/6 Prostaglandin D2. PGD2 is a mast cell mediator your IgE panel does not measure. Elevated PGD2 confirms degranulation through non-IgE pathways. The single most useful addition to a standard allergy workup for Long COVID patients.
Exercise intolerance in Long COVID is not one problem. It can be three distinct patterns, each driven by different biology, each requiring different management.
2/6 Pattern one: oxygen delivery. Damaged capillaries cannot deliver oxygen to working muscles fast enough. Heart rate spikes disproportionately to effort. Lungs and heart test normal.
3/6 Pattern two: energy production. Oxygen reaches the cells but damaged mitochondria cannot convert it efficiently. You tolerate low activity then crash 24-48 hours later. Classic post-exertional malaise.
Three hormone markers your doctor probably is not checking in Long COVID. And what each one actually tells you.
2/7 Free T3. TSH tells you what your brain asks the thyroid to do. Free T3 tells you what your cells actually receive. Normal TSH with low Free T3 means conversion is stalling. Cost: $30-50.
3/7 This is common after viral infections. Your thyroid may be producing T4 just fine. The conversion to the active hormone, T3, is where it breaks down.