DH has sarcopenia

His walking has become really bad over the last few years, more of a shuffle now. We thought it might be connected to a condition he has in his legs or spinal stenosis which showed on a scan sometime ago but not having problems with his back.
We decided to try a physio to see if there could be any help for his walking and she diagnosed the above. We've only seen her once so far. He did some exercises and we are now doing three of them at home as requested and then will see her again in a week's time. We've googled the condition but it was the first time we'd heard of it. We've seen various consultants over the years and not one has mentioned it. Walking is highly recommended so we're doing this (not too far at this stage). He's very slow. I believe its not reversible but we don't know much else about it. Just wondered if anyone had any info they could pass on.