Every time it has happened to me has been the same thing. 1st time was shoveling a lot of weight while twisting and throwing it. 2nd time was lifting and spinning some heavy grain vacuum hose then this last time was just tossing some logs after manhandling a bunch of trunk pieces. But I know my weight is the main culprit. Funny thing is I had a great workout in earlier in the day with all the swimming we did. But I went home and napped for awhile before going to my buddy's. I just said to him that my back was starting to feel it so we took a 10 minute break and drank some Gatorade. I was literally on the last small piece when it popped. If the nasty weather they are calling for tonight doesn't fugg stuff up, then we are hitting the gym for some good cardio. I also need to work out my right knee. I trashed it in High school when my spikes dug in sliding into 3rd base. It sent my ass somersaulting and ended the year for me since we had a couple games left. I never got it looked at but it has always given me fits if I don't keep working it out.