Hey girl. I have a couple of secrets for hair care at the gym.
For starters, if you have hair long enough for a pony tail then buy two cotton sweat bands, like the ones basketball players where. After you pull your hair back, side it over your edges. It will keep your hair laying flat and sweat off of your face. The reason I said buy two is because if you want to take it one step futher, line one with satin. Go a fabric store and you can get a little piece for just about nothing. Save the satin one for when you leave the gym. Spray your edges with a little water or braid spray and use the satin lined band until it dries. It will keep them smooth and mositurized.
When I work out and get really sweat and hot and nasty, dealing with my hair can be hard. What I like to do though when I get to the locker room is part my hair with a shower comb or my fingers (depending how many weeks post I am) into four or more little sections. I use HUGE roller on each section to help aid the drying process and keep my ends smooth. Now you can wait to you get home to do this is if you feel uncomfortable. By using a big roller, I don't get tight curls but it helps my hair dry smooth enough to finger comb and flat wrap at night which will give me a smooth style in the morning.
When I have alot of new growth going on I plan my workouts better. For example... If I normally wash on tuesdays and saturday then my most intense cardio sessions are going to be the day before or the day I wash. For the rest of my cardio sessions I do longer endurance training which gives me a good cardio workout and, for me atleast, gives me less sweating.
I have a very tempermental scalp and I get horrible itchy spells out of the blue. Sweat and an itchy scalp don't mix so I keep anti-itch braid spray, cortisone creams and anti itch zine creme (by creme of nature) in my gymbag. I also use shampoos once a week or once every two weeks designed for itchy scalps. Its much easier prevent a flareup instead of treating one.
When all else fails, have a back up plan. Sometimes, no matter what you do, you hair might not act right. Always have octopus clips on hand or other clips that allow you to make buns. I also will get my hair set very tightly curled so that I as I workout during the week, they gradually fall and I get the messy sexy look. The key in making what every style you decide look is best is anti-frizz products. Make sure your hair is mositurized so you will get less frizz and keep a little tube of anti-frizz cream and serum on hand.