Consuming fluids during exercise keeps your blood volume up and your core temperature down. Both help you fight fatigue so you can continue to perform at your best.
When you sweat you lose more than water, you also lose electrolytes. Electrolytes like potassium and sodium play a key role in brain-to-muscle communication, which is important for performance. Intense workout may lead to intense sweating, and you have a lost to lose during a game or practice, the average hockey player loses 1.5L of sweat per house, and in certain cases sweat loss can account for more than half you entire recommended daily intake of sodium.
Carbs are the preferred fuel source for your brain and muscles. During training, you may use or deplete carbohydrate energy stored in the form of glycogen which can negatively affect performance. Your body breaks down carbohydrates into sugar molecules, for your brain sugars can help improve concentration, helping you make better split second decisions during the game. for your muscles, they are easily digested, absorbed and quickly oxidized to provide energy during high-intensity or prolonged exercise.