Gattoni, Chiara, Abbasi, Asghar, Ferguson, Carrie et al. · Respiratory physiology & neurobiology · 2025 · DOI
This study tested whether Long COVID patients experience a measurable drop in exercise capacity after 24 hours, which would suggest their bodies aren't recovering properly from exercise. Researchers had 15 Long COVID patients do exercise tests on two consecutive days and found no significant difference in performance between day 1 and day 2. Surprisingly, this was true even though 80% of patients reported post-exertional malaise (PEM) symptoms over the previous six months.
This study directly addresses a core feature of ME/CFS and Long COVID—post-exertional malaise—and uses objective exercise testing to investigate its mechanism. Understanding whether PEM involves measurable physiological changes on repeat testing is crucial for developing targeted treatments and validating diagnostic criteria for these conditions.
This study does not prove that PEM has no physiological basis; rather, it suggests the mechanism may not involve reduced aerobic exercise capacity recovery within 24 hours. The findings do not rule out other physiological explanations for PEM, such as delayed symptoms beyond 24 hours, autonomic dysfunction, or metabolic impairments not captured by standard CPET measures. A negative finding with a small sample size cannot definitively exclude differences that might appear in larger or more sensitive studies.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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