Importance of Fluid Supplement During Endurance Exercise

Journal of Exercise Nutrition & Biochemistry 1998;2(1):25-44.

Abstract

B
ody fluid and electrolyte loss increase during prolonged endurance exercise and the sweating rate largely depends on environmental temperature, humidity and physical activity. For every liter of fluid lost, core temperature rises 0.3℃, cardiac output declines 1L/min, and heart rate rises 8bpm. Since it has been known that dehydration state by severe sweating cause heat stroke, fluid supplement is emphasized. The optimal amount of fluid depends on exercise intensity, time, environmental condition, and individual physical condition. The increase of sodium intake facilitate glucose uptake on small intestine. The large amount of hypotonic fluid intake or none intake of water during prolonged endurance exercise could lead hyponatremia. But, it has been known that sodium depletion is happned only triathlon or ultra marathon which has longer distance and time than marathon. The types of carbohydrate fluid are used as energy source. As under 20g of carbohydrate is oxidized in the first hour of exercise, thus 3∼5g/100mL of carbohydrate intake every 10minute could maintained 1g/min of carbohydrate oxidation rate. Sports drink such as carbohydrate-electrolyte combined drink is known to prevent hyperthermia and to increase endurance exercise performance. As discribed above, we thought that fluid supplement and nutrient during prolonged exercise is essential and, further research will be need to enhance exercise performance.