so here's a little basic medical bruise info.
http://www.moondragon.org/health/dis.../bruising.html
I did a bit more research just now than I usually do, and found really nothing to indicate that a healthy individual could suffer any lasting trauma from bruising. Nothing to indicate a differentiation between soft and 'hard' tissue bruising. In fact, medical texts say that soft tissue is all tissue except bones and such.
Did not know that. ^.^
So here's the caveat to my earlier statement. Should bruising have occurred due to impact play there is a risk of fracture. Unlikely, but I think the accepted figure is 8 lbs of pressure to break a human bone.
Imma stick to biting (and flogging) the fleshy bits ^.^