I think rugby is the toughest sport out there. Those guys are just insane and don't wear any padding. English football, being just soccer, isn't any rougher than NBA basketball. You are allowed to bump a little, but get a foul called if its excessive.
There was a comment made earlier about some NFL guys being excessively large. Well, there are multiple defensive and offensive linemen going to the Pro Bowl who are in the 340+ pound range. 300 pounds is the norm. Its amazing how quick these big guys are, and it typically takes two 250 lb players to guard them....or another 340 pounder. They have a singular job function: don't let anyone get by them...and they do it well. They are professionals, so stay as huge as they need to be.
...back to language... "knickers" ....is this the English word for underwear or do people in America use it?