Nutritional requirements during performance include the need to maintain hydration and for extended periods of exercise, taking opportunity to replenish blood glucose levels.
During performance an athlete needs to maintain hydration. Hydration aids performance and dehydration hinders performance, decreasing concentration and reducing the body’s ability to function. All athletes sweat at different rates during performance, but it is recommended that they drink around 1L spread throughout every hour of activity. The more frequent this consumption the better, so a marathon runner might drink some water every 5 min, while a rugby player may drink every 10 min depending on the events on the field and stoppages.
Athletes can also assist their performance by consuming some sugars often provided in sports drinks such as Gatorade or PowerAde during performance. These drinks provide additions glucose that goes into the blood and is transported to the muscle for use in either the aerobic or lactic acid energy systems. This delays fatigue in these systems because it spares muscle glycogen to be used later in performance. Consuming sugar during competition also allows for higher intensities to be maintained for longer during performance.
The salts in sports drinks help the body to hold fluid and replace the salt lost through sweat production. Salts lost through sweat include, sodium and potassium. Salt in blood helps to retain fluid, particularly preventing fluid loss through excrement, requiring water to remain in the blood and not be filtered out by the kidney tot he bladder.
So an athlete in an AFL game might consume Gatorade to replace fluid and salt lost through sweat, and in order to gain glucose to aid performance by delaying fatigue caused by glycogen depletion.