Do you use back support for digging? if so, what do you use?
I have a tailor-made corset going cheap??
ray has a neoprene one and a weight lifting belt for the really heavy work, apparently, the neoprene's easier to work in but not as effective..got from e bay, :)
Don't actually do much heavy digging here, tend to use a fork. I put the spade or fork in with the handle pointing slightly forward, push it in with foot, pull back using arm muscles, and the soil comes up with leverage. Also, I do it in small amounts, not trying to dig up great chunks at a time. Lots of info on this site about no-dig methods too, ;D it's worth a search.
I have a bad back & have a technique that involves barely moving my back - just use arms & knees. It feels odd to begin with but I can keep going for hours. Digging, that is...
I use an azeda rather than fork/spade as the weight of the blade works the ground itself...