Crikey! DS is a kickboxer - I used to do karate. The only reason I could ever 'beat' him when he was younger (I wouldn't dare now) is because the disciplines are different and he never did learn to anticipate the 'different' moves and blocks that I used (and I had spent years watching his classes so had a fair idea).
He would absolutely annihilate me now. The girls/women in his class are shorter, lighter and have less muscle that he does. He is a solid mass of muscle (even when he has been lazing on his bum for the past year). He says they don't generally mix the sexes but when they do, he has to 'go light' on the females because he knows he could hurt them. I would even say that a male much lower belt could dominate a female higher belt.
I've seen people in the gym come back from events with injuries, black eyes, bruises - even one of the sensei's had his leg badly damaged in a competition so that he was out of competition for months.
What are they thinking? Sport isn't a flipping 'right' and even so - it should be fair.