This is a new issue that's developed. First of all, I'm 60ish and play regularly. I played a week-long musical recently and then this weekend played lead on a 4 hr big band gig Saturday followed by 3 church services the next morning. Both the musical and this weekend were arduous. The day after these 2 events my lower back was really sore. I didnt make the connection until after the most recent blow. Does anyone else have this problem...is it normal or am doing something different/incorrect or am just getting to the old f..t stage?