Post-polio syndrome is a poorly understood condition that can affect people who have had polio in the past.
Polio is a viral infection that used to be common in the UK, but is now rare.
Most people who had polio would have fought off the infection without even realising they were infected.
Some people with polio would have had paralysis, muscle weakness and shrinking of the muscles. But usually, these problems would have either gone away over the following weeks or months, or remained the same for years afterwards.
Post-polio syndrome is where some of these symptoms return or get worse many years or decades after the original polio infection.