Could you ask her? Either alone or at the time it's happening.
"Is everything alright Wendy? Only I've noticed you seem to be blocking me from conversation at the sports group?"
If she says she's not, and she will more than likely say you've imagined it, that's the time to bring it up again when you are at the group.
"Wendy, this is what I meant the other day, you seem to be contorting yourself to avoid looking at me and you've hardly said a word to me all day."
Or possibly if you don't want to come right out with it "Is something wrong with your neck Wendy? Because you seem to be hunched over at a very odd angle. I'm starting to think you're trying to avoid looking at me haha. Shall I move so you can see me, would that make you more comfortable?"
Then every single week that follows and she does it, ask her if her bad neck is playing up again and should you all move so she can see you all. If she denies the bad neck just say "Oh, your neck's fine, well it must be me you're avoiding then haha. Budge up then so we can all join in, I'm starting to feel like billy no mates over here."
I realise that's not as easy as it sounds, but if you feel brave enough to have a go it might just throw a spanner in the works of whatever it is she's up to.
Also, if she is Wendying you, you either won't be the first or you won't be the last. Keep your eyes and ears open because eventually you will find out about her doing it to somebody else as well.