Okay, I'm going to open a can of worms here.
What do you mean, when you talk about "using your back" or "back tension"?
I've heard umpteen ways of talking about it over the years, ranging from the ludicrously simplistic ("think about trying to crush a matchbox between your shoulderblades") to the hideously technical. I believe that any (all?) of the explanations I've heard are open to misinterpretation.
So I guess there are two points which I'd like discussed:
1. What do you
do?
2. How do you describe it?