A core sample is a cylindrical section of (usually) a naturally-occurring substance. Most core samples are obtained by drilling with special drills into the substance, such as sediment or rock, with a hollow steel tube, called a core drill. The hole made for the core sample is called the "core hole".
When you combine flour with liquid and stir or knead, the proteins in the flour form gluten. The gluten in the flour develops and becomes strong and elastic, forming a network of tiny air cells.
It is recommended that an athlete consume 16 ounces (two cups) of water two hours before exercise begins. Another eight to 16 ounces (one to two cups) should be consumed 15 minutes prior to exercise.