There is plenty of evidence already by the people who have posted, but I thought I might just add my story.
I screwed my back when I was 14 at Jungle Gym. Landed head first with my hands by my side into a foam pit. My mates and I were trying to do tripple forward flips off the tramampoline


I compressed my spine and since then Ive always had problems... BUT since SUPing I havent had a single morning when I have woken up with a tweeked back!
I also did my knee windsurfing and now that too has never felt better!
Im amazed at the way SUPing helps your body in a good way. But saying that Ive had some pretty nasty accidents resulting in getting hit by my board

I say go for it!