I think my right leg has always been a little weaker than left side due to multiple surgeries etc... But for the most part barely noticeable...

This past few months it's regressed and fealing weaker and weaker on runs. I've started some additional strength training but am not sure what the cause is.. The only difference between now and the past decade or so is I am doing 0 treadmill runs. I'm thinking the tm runs forced my form and kept both legs balanced and now running outside only since covid I've probably started favoring that side and my leg has weakened...

Any run coaches ever see something like this? Any ideas... My pace slipped by 30ish seconds per mile on training runs and am not able to run as long either...