Since the earliest stages of the pandemic, muscle weakness has been a key symptom described by patients post-COVID infection. Estimated to affect up to 60% of those with long COVID, it can have a profound effect on the ability to carry out activities of daily living.1 Many patients describe a fluctuating pattern to such symptoms, which can be triggered by exercise or fatigue.2 Most of these patients do not receive any muscle-specific investigations and many are told that they are experiencing the impacts of deconditioning or that they have a psychological or functional disorder. Such patients are often prescribed antidepressants or diverted down rehabilitation or psychological support pathways. Although some patients find this helpful, many patients experiencing muscle symptoms do not benefit from such approaches. Two case studies are given in Box 1.

As more is learned about the impact of COVID on the neuromuscular system, recent research has highlighted a variety of ways that COVID damages muscle and nerve cells,3 resulting in muscle weakness. This changing knowledge needs to lead to changing practice. It is therefore time to deploy Maya Angelou’s advice, ‘Do the best you can until you know better. Then when you know better, do better.’

COVID can damage the mitochondria and interfere with the electron transport chain supplying energy to muscles. This leads to fatigability, weakness, and reduced exercise tolerance,4 all of which can be exacerbated by poor sleep or nutrition, or intercurrent viral illnesses.5

During acute COVID infection, motor neurones and adjacent muscles can be directly damaged by the virus or by the immune response.6 Some patients will present with acute Guillain–Barré syndrome,7 whereas …