Here’s something I saw the other day, and I stood there and looked at it for awhile trying to figure it out. I get that it’s a fitness club. What I don’t get is how to pronounce it.

Could be Yootside, sort of like a fitness club for youths pronounced Joe Pesci-style.
Could be a combining form of you and outside, which still leaves the pronunciation a mystery since the ou in you and outside don’t share the same sound, so it would look like it should be pronounced yowtside. Yowza.
Maybe the Y is pronounced separately, so it’s a question, as in Why outside? Good question. Why outside? Well, why not outside?
Looks like the answer is on their website:
In short, it should be about you. And if you’re like us you prefer to exercise outside. You + Outside = Youtside!