premise: Baltimore Marathon 2005 . up at 6 00 am to have a bagel with light cream cheese , and a big glass of ice water . pinned on my race number , put on my runner 's watch and knee brace , nike socks , laced up my shoes . threw on sweatpants and a long sleeved tshirt because it was chilly in the am . add yellow hat and i ' m ready to go . Why did the writer have a big glass of ice water ?
hypothesis: Because they were thirsty .