What’s the biggest factor affecting your performance?
Fluid replacement is unquestionably the most important dietary essential in maintaining exercise capacity.
Why is appropriate hydration important?
Water maintains blood plasma volume, regulates body temperature and is crucial in the contraction of muscles. A loss of 2% of body weight, due to sweat, increases the risk of nausea, diarrhoea, and vomiting. A loss of about 5% of body weight, due to sweat, can decrease work capacity by roughly 30%.
How does it work?
Dehydration will lead to increased blood viscosity (thickness). This is due to the decrease in blood plasma volume and thus reducing the volume of blood returning to the heart and consequently decreasing cardiac output. In short one’s ability to get oxygen and much needed nutrients to the muscles at work are massively hindered.
An increased core body temperature can lead to an increase in glycogen breakdown. Contributing to a faster rate of fatigue. The breakdown of glycogen is largely responsible for the build-up of lactic acid, changing the pH of the muscle causing further levels of fatigue.
The University of Connecticut conducted research on athlete’s hydration status and their muscle growth during resistance training over a period of three different states: hydrated, moderately dehydrated (2.5% of body weight) and critically dehydrated (5% of body weight). Researchers drew the athletes’ blood and examined certain molecules directly correlated to muscle growth. The athletes in a dehydrated state had an increased level of cortisol, stress hormone, which reduces the level of testosterone one can produce, the primary hormone required for muscle growth.
Thirst is a poor indicator of one’s hydration status. Once the sensation of thirst occurs the body is already dehydrated. The simplest way to maintain an optimum hydration status is to observe the colour of urine. It should be pale or straw coloured, any darker suggests the re-uptake of fluid is necessary.
What to drink?
Isotonic, similar electrolyte concentration to that maintained in the body. Quickly replaces fluids lost during sweat. Team sports/ middle distance runs Hypertonic, higher electrolyte concentration to that maintained in the body. Post workout to top up glycogen stores. Ultra-marathons, and must be consumed with excess fluid to actually hydrate the body Hypotonic, lower electrolyte concentration to that maintained in the body. Rapidly replaces lost fluid. Used when athlete require fluid but not electrolytes.
Water is a major component of many chemical reactions on a cellular level in the body, whether for athletic performance, focus or for overall health. Research suggest that it’s almost impossible to reach maximal physical performance when dehydrated, due to the impact it has on the body’s ability to maintain osmotic homeostasis.
Article by Blake Mowatt
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