Does your DC compete in a high level sport?

[SportNovice]

So I am the most un-sporty person you will ever meet and I don't know where DC gets it from but she's doing quite well at the moment. I, however, am out of my league. She never seems hungry before matches (nerves?) but I need to feed her. What do your DC eat on a competition day? And the day before?
I've been taking along e.g. a cheese sandwich , some carrot sticks, apple, fruit pie, couple of cereal bars which she just picks at. In the second half of the competition, she seems out of energy. Most other people seem to have a whole array of food to offer their offspring. What should I be providing?

DH was a fencer, national and international level. He never ate in a particular way before competitions. On the day though he would eat plenty of high carb, sugary snacks in between the rounds.

There are some great resources out there. DD2 swims and has a 3 day count down to race day developed by a specialist sports nutritionist hired by the club. Hearing it from someone else made 100x more impact than me wittering on.

Agree with previous posters that the sport makes a difference, DC3 is national level gymnast and their fuelling looks completely different to the swimmer.