Tell me about it. I can put out the same effort in a 10k as I did 15 years ago and be 30% slower. Since my turnover isn't much different, that means each stride is 30% shorter. In the past, the way I would get power and efficiency back in the legs was to do speedwork; but now that always leads to injury for me. Between a rock and a hard place.
My tissues won't hold up to much training, and distance seems even worse for me than speed work. I am still nursing some extra hamstring tenderness I seem to have picked up on the treadmill a week or so ago.
I remember in HS I could see my stride's length from the divots in the track (cinder surface, real SPIKES on the shoes), was about 7 feet! Probably couldn't do a long jump that far now.