I’ve been training for over 25 years and powerlifting for more than half of the time. Also, I got my CSCS in 1998.

Last night I had some positive results. I started off by hitting both internal and external shoulder rotation mobility. My internal rotation is very lacking. Then I did some barbell bench press and things felt better on the low back. I did use the slingshot to help reinforce the shoulder external rotation during the movement. In the past when I’ve tried the sling shot it hurt my shoulders which was probably an indicator of lack of internal shoulder rotation. 

I’m thinking that because my shoulders lack the internal rotation that the bench press is causing excessive tension all the way down the back leading to pain in the SI joint area. I’m hopping with regular work on this I can get normal ROM and not have the lower back pain. 

I will continue on this path unless there are other ideas.

Thanks