When is it time to swap traning shoes?

Hi everyone,

I hope this finds you well!

How do you recognize that your training shoes are used up and need to be swapped? Aside from the obvious scenario of you ripping them to pieces, of course :D

My first pair of training shoes has been with me for a couple of years now, but it still looks like they're in a mint condition. However, I have the impression (I'm not 100% sure, it's a marginal change) that my left shoe forces my leg into an unnatural angle that causes me knee pains after more intensive workouts. I don't think this used to be the case in the past, though I had experienced knee pains every now and then. Is this even possible or am I making this up?

Best wishes,

Natalia

Edited