Is it normal to enjoy over powering my bf

Everytime my BF and I use our hot tub I like to leg wrestle him. I love beating him. I won our little tournament with some guys and girls. He has a very muscular upperbody but his legs not so much. I have much skinnier weaker arms but bigger muscular stronger legs. I enjoyed beating him more than the other guys because his upper body is so muscular. I love watching him strain to ward me off but his legs are not strong enough. It turns me on but he gets all quietly pissed.