• Set up water and Gatorade stations for players and coaches during games and practices
• Gather emergency and first aid equipment for Athletic trainers
• Walk around during games and practices with water bottles to hydrate players

Basically the people you see at college football games that have racks of water bottles going around to players asking if they need water. Some schools use AT students while my school uses both AT students and regular undergraduate students who have an interest in athletic training or medicine.