Hmmm, not in the US, so I am thinking you probably have different hair products than us.
My daughter has straight long hair and she has an awful lot of it. I can never do her hair, even on a non gym day, without first spritzing it with water. For gym, well without product and hairspray she looks a wreck within about 30 mins.
For competition hair what I have found works well is -
I always style her hair wet ( I find it easiest and quicker to do it after a quick shower rather than spritzing it down with water).
I add the strongest hold gel I can possibly find, and lots of it.
Style the hair, spritz with water to smooth down any flyaways. run some gloss serum over the front and sides.
Spray with a colossal amount of hairspray.
Spray again with glitter hairspray.
The gel I like is
this one by Taft. In Aus it is available at most supermarkets, pharmacies and hair and beauty stores. The trick is lots of gel.
I generally use
Link Removed by Garnier.
If you are styling the hair really wet, remember to allow for the fact that hair "shrinks" as it dries. One comp poor dd had a high ponytail, divided into 12 little plaits which were then tucked under and a ribbon tied around, not a hairdo that is easily adjusted after it is done... all was good until her hair dried and it was then so so tight! She had a headache all session poor thing
For training, dd comes straight from school, she generally has a small amount of mousse in her hair in the morning for her school hair do and some hairspray. Her hair is always messy at training, but as long as it is out of her eyes and not a safety issue the coaches don't mind.