Hernia?

I keep hearing about people getting hernias from heavy lifting.

When is a hernia most likely to occur? (eg. during very heavy backsquats?)

How did Ben Johnson and others in his group lift such heavy weights on weekly basis without it ever happening to them? (apart from always wearing a belt and doing a lot of low intensity ab work)

i had a slight hernia (it was more of a small rupture of the upper quad, sounds better for an athlete to have a ruptured quad than a hernia) in the fall of 95, had to go under the knife to get it fixed.

it happened in the wieght room as i was doing very very heavy leg press with a bodybuilder friend of mine and on rep 12 heard a “pop” then some tightness and some isloated pain.

it wasnt torn too too bad, and wasnt painful but everytime i lifted my leg forward the muscles didnt work right. so i got it fixed and missed 5 weeks of training but its been 100% ever since.

the doc figured that my connective tissue was lagging behind my muscle development, so the quads could handle the heavy wieght but the connective tissue couldnt.

Do you think this type of injury was related to the type of movement being performed? (Where full range of motion is unable to be achieved, so the supramaximal loading occurs where the muscles are being loaded with a weight that the connective tissue cannot handle) in combination with lifting to failure?

Sorry if I have just stated the obvious, but I know not a thing about hernias, apart from the fact that my friend just got one (on the Total Gym?!?!, of all equpment) and I definately don’t want the same to happen to me.