Hmm, I checked these out and it's not my flavor.
I like the idea of it being an inspiration though! I think the shirts I saw were too wordy and busy for anyone to see well from far away, so they'd have to be up in my business to read it. It looks like they made the prints in WordArt and then just transferred it to the t-shirt. Just my .02!
I'd LOVE to have some cool tennis t-shirts though. I'll have to go searching now.