How to make a strong bun for athletes?

so I am a really competative athlete. I keep my hair in a pony tail for taekwondo and all my standing martial arts, but when I start grappleing in jujitsu it doesnt work. I have really long hair now so they always hold me down by my ponytail and it slows me down a bit, when i put it in an easy loose bun it comes out too easily. How do you make those buns that dont come out. Ive seen it done, its a bunchof twist and stuff but i can't figure it out. and i cant find it on google either. please help before my next training!