I don't know, I never got to the bottom of it. I'm guessing it's muscular but don't know for sure. It goes away when I do stretches regularly, but I've just been a lazy ass lately and haven't been doing enough stretches. It's playoff time with too many games to watch and follow, plus work had been pretty busy, you know the usual excuses for not taking care of the body.

Muscular or disc issues? I had a pretty bad herniated disc almost two years ago. Had to walk with a cane for a couple weeks and didn't totally heal for a few months. I am very cautious now when I start to feel any pressing of the disc on my sciatic nerve. I will rest it, ice it, then heat it up and use the stretching pillow and do other stretches to try and nip it in the bud right away. 

grayruby

I have lower back pain issues, so I'm hoping this will help with the back pain.

gnilma

Stacker Saloon

saloon

It feels great but I can't do it for too long, it is one of the few things besides actual pitching that irritates an old rotator cuff injury I had. 