you shouldn't be doing highbar, it increases the tendency to have lumber flexion at the bottom ("ButtWink"), possibly why you have low back pain. Watch your butt tuck under you at the bottom. the reason for this is that high bar and ATG and especially ATG high bar squats cause you to round your low back to achieve that kind of depth. Switch over to low bar witch makes it much easier to achieve depth without rounding your low back. Also tha