Define Pre-Exercise or Pre-Event Meal for athletes?

Suitable foods in adequate quantities at all times should be consumed but before the event, strategies to fuel up the energy system and proper hydration are amongst the primary goals. Conditions like hunger, fatigue, weakness, light-headedness should be prevented and a comfortable gastrointestinal state is desirable. Thus, the goals of pre- event meal are:

To fuel up muscles and brain: As explained earlier that energy for high intensity endurance physical activity is supplied by muscle glycogen. Therefore, adequate glycogen stores are crucial to optimal athletic performance. 

Energy for the brain is supplied by glucose from the blood. Blood glucose is replenished from liver glycogen stores. During sleep, breakdown of liver glycogen and release of glucose into the blood keeps blood glucose levels normal. By morning, liver glycogen levels are low. Therefore, eating carbohydrate-containing foods before exercise refills liver glycogen stores and can "top off" muscle glycogen stores.