Hydration and Performance
The human body does not sense dehydration very well, with stimulation of thirst occurring after the body has already lost 1% of body weight in water. Exercise performance decreases with as little as a 2% drop in body weight from dehydration. So there’s a small window for athletes to respond to thirst before performance is impaired. Dehydration decreases exercise performance due to decreased plasma volume, which increases heat stress and core temperature, decreases VO2max, increases heart rate and perceived exertion, increases glycogen utilization which can lead to early fatigue, and alters central nervous system function leading to decreased motivation and effort.
As a result, athletes need to drink before they are thirsty, and must start each exercise session in a hydrated state. Increasing hydration before and during exercise is one of the simplest ways to improve exercise performance. Optimal hydration takes place in the days and weeks before an event or after a hard workout. Electrolytes in combination with water is invariably better than water alone and can bring your system into balance more quickly by helping you retain more of the liquid you ingest. The bottom line: Don’t underestimate the importance of hydration on race day, but more importantly in your overall training and nutrition plan; it’s one of the easiest ways to boost performance.