Amsterdam institute for Immunology and Infectious Diseases

Researchers from Amsterdam UMC and Vrije Universiteit Amsterdam (VU) have identified a physical basis for the enduring fatigue experienced by post-COVID patients. Professor of infectious diseases at Amsterdam UMC, Michèle van Vugt, notes, "We observe muscle changes in these patients." The study's findings were published in Nature Communications.

The research involved 25 post-COVID patients and 21 healthy control participants. Each participant underwent a 15-minute maximum exercise bike test, triggering prolonged symptom exacerbation known as post-exertional malaise (PEM). PEM manifests as extreme fatigue following physical, cognitive, or emotional exertion, with the exertion threshold varying among individuals.

Energy depletion

Examining blood and muscle tissue one week before and one day after the exercise test, VU movement scientist Rob Wüst reports, "We observed various abnormalities in the muscle tissue of the patients. At the cellular level, we noted decreased functioning of mitochondria, the cell's energy factories, resulting in less energy production." Van Vugt emphasizes, "The fatigue is biologically rooted. Muscles require energy for movement. This discovery allows us to explore effective treatments for post-COVID individuals."

Coronavirus presence

Contrary to a hypothesis suggesting lingering coronavirus particles, Van Vugt states, "We currently find no evidence of this in the muscles." The researchers also confirm normal heart and lung function in the patients, indicating the reduced condition is unrelated to cardiac or pulmonary abnormalities.

Counterproductive exercise

Exercise may not always benefit post-COVID patients. Infectious diseases physician-researcher Brent Appelman advises, "We recommend these patients monitor and avoid surpassing their physical limits. Opt for light exercise that does not worsen symptoms, such as walking or cycling on an electric bike, to maintain physical condition. Recognize that each patient has a unique limit." Van Vugt cautions, "Given symptom exacerbation after physical exertion, some traditional rehabilitation and physiotherapy approaches can hinder recovery in these patients."

Post-COVID symptoms

While the majority recover within weeks after SARS-CoV-2 infection, a small group develops post-COVID symptoms. These symptoms, alongside PEM, include severe cognitive problems (brain fog), fatigue, and exercise intolerance.

Read the post-COVID research published in Nature Communications here.