Actually, there are two reasons…Many have said because it gives the opponents less to grab which is true, but the other reason is that it holds the padas where they belong. Thigh pads stay on the thighs and Knee pads stay on the knees. As for the UK chum who thinks it’s girlie, I find it interesting that Rugby players who try american football aren’t able to hack it, yet a washed up NFL Wide receiver can go over to the UK and be a dominant force in “their” sport!LOL! Line your best rugby player up against NFL players like Ray Lewis w/o pads and your rugby players will soon find out why pads are necessary. It’s easy to tackle someone from the side or from behind as in Rugby, but in the American game it’s face-to-face, smash-mouth contact!