Worked my upper back last week. Somehow between all of the snow removal, tree trimming and snowshoeing, I locked up some of my muscles around the T-spine. Was a little sore but had sudden, breathtaking pain on bending forward on Sunday. Hot tub relaxed it and helped. Saw the chiro 1st thing Mon. Sore after but much better on Tues. Been resting since to let it get better. I think it's ok now.