So i was doing Scott's Legs-B workout today and doing some box squats when I ran into a few problems. Ive looked around but I cant find much of anything that is helpful in explaining how different the form is when performing a box squat compared to a regular back squat.

During todays workout I think i may have been plopping down on the box a little, but i also think i may be rolling back a little at the bottom of the movement; the result is my lower back isnt feeling great at all right now.

So my question to you nation is this, what is the difference in form when performing a box squat? should i be sitting back and engaging my hamstrings more to prevent rolling back on the box or is there something else i'm missing? Also of note is i was using a box that put me right about parallel, should i perhaps use a higher box?

Well, when you sit back to do the movement you still need to keep an arch in your back.. when you sit on the box there should be no "falling back" feeling... if there is.. you need to bring your feet closer to the box so when you sit you do not lose the arch in your back :-D