Muscle fatigability and post‐acute COVID‐19 syndrome: A case study

• Published in: Physiological reports 2022-08, Vol.10 (16), p.n/a
• Main Authors: Fanous, Jacob, Zero, Alexander M., Rice, Charles L.
• Format: Article
• Language: English
• Subjects: Action potential; Body mass index; Case Report; Case studies; Cognitive ability; Coronaviruses; COVID-19; COVID-19 diagnostic tests; Disease transmission; dorsiflexors; Electrodes; Electromyography; Fatigue; Infections; Laboratories; Long COVID; Losses; Muscle contraction; Muscle strength; neuromuscular physiology; SARS‐CoV‐2 (COVID‐19); Severe acute respiratory syndrome coronavirus 2; torque steadiness
• ISSN: 2051-817X
• DOI: 10.14814/phy2.15391

The acute phase of COVID‐19 has been well studied, however with increasing post‐acute COVID‐19 syndrome, much is unknown about its long‐term effects. A common symptom in both the acute and post‐acute phases has been fatigue, assessed predominantly qualitatively. Here we present a case study objectively assessing neuromuscular fatiguability in a young male (27 year, 1.85 m, 78 kg) who continues to experience COVID‐19 related fatigue and cognitive dysfunction, including other symptoms, 12+ months post‐infection. Prior to infection, he was part of a neuromuscular study forming the basis of our pre‐COVID‐19 results. The study was repeated 12 months post‐COVID‐19 infection. Muscle strength, endurance, torque steadiness, voluntary activation, twitch properties, electromyography, and compound muscle action potential were obtained and compared pre‐ and post‐COVID‐19. All measurements were done using a dorsiflexion dynamometer in which the participant also was asked to produce a one‐minute fatiguing maximal voluntary contraction. Muscle strength, voluntary activation, and fatigability (slope of torque) showed no meaningful differences, suggesting intrinsic neuromuscular properties are not affected. However, torque steadiness was impaired three‐fold in the post‐ compared with pre‐COVID‐19 test. The participant also reported a higher level of perceived exertion subjectively and a continued complaint of fatigue. These findings indicate that muscle fatiguability in post‐acute COVID‐19 syndrome may not be a limitation of the muscle and its activation, but a perceptual disconnect caused by cognitive impairments relating to physical efforts. This case report suggests the potential value of larger studies designed to assess these features in post‐acute COVID‐19 syndrome. Post‐acute COVID‐19 syndrome has long lasting implications on the body, such as fatigue and cognitive dysfunction. When assessed objectively, fatigue in post‐acute COVID‐19 appears to be a limitation of cognition and not the muscle per se.