After a neurological injury, whether a spinal cord injury, a peripheral nerve injury, or a period of enforced immobility, clients often ask: "Will electrical stimulation bring the muscle back?"

I have learned to pause before answering, because "back" hides two quite different questions. The first is about size: will the muscle get bigger again? Obviously, this is what people notice when they look down at their legs. The second is about substance: will the tissue that returns actually be muscle, in the working sense of the word, rather than a mixture of shrunken fibres, fat and scar? This is less obvious to a client, but it's what we actually need. Researchers call this second property muscle quality, and it is the more important of the two. It is also the one that almost nobody explains to patients.

In this article, I want to walk through what muscle quality means, how it is measured, what happens to it after injury, and what electrical stimulation has been shown to do about it. I will cover both of the situations we work with: innervated muscle, where the nerve supply is intact and conventional stimulation applies, and denervated muscle, where the nerve supply has been lost and an entirely different approach is needed. The evidence differs between the two, and so do the limits of what is possible, and I will be plain about both.