We're regularly exhorted to drink 8 glasses of water per day - but where does this figure come from? And do we really need that much water?
The magic figure of 8 glasses is probably based on the finding that sedentary adults lose at least two litres of water per day in cool environments. Add in any level of activity, or an increase in temperatures, and that can easily double.
Of course, we get plenty of water from the foods we eat - most fruit, for example, is simply packed with water - but there are also foods that require extra water to digest them. Alcohol and salty foods would be an example of this.
It is therefore recommended that you drink at least 8-10 cups per day in order to maintain efficient bodily functions. Our body requires sufficient water for almost all vital processes, including:
- Blood pressure
- Cell functioning
- Glucose transportation
- Heart function
- Joint lubrication
- Regulation of body temperature
- Waste elimination
Dehydration has serious consequences not only for the serious athlete, but indeed for all of us. Doctors estimate that anywhere from 70-90% of all headaches are caused by dehydration, while for those who are training or racing in hot weather, lack of fluids can cause decreases in performance, muscle fatigue and the risk of heat exhaustion.
The key to staying hydrated is to start drinking before you feel thirsty. This means that you should drink a glass of water (8 oz) around 20 minutes before a workout or race, then continue drinking the same amount every 20 minutes during your workout.
Unless your workout is longer than 90 minutes, water is your best choice. Ideally it should be cooler than the ambient temperature in order to facilitate rapid absorption by the stomach.
After your workout, drink either water or watered down fruit juice. Soft drinks and alcohol have no nutritional value, but are packed with calories. In addition, alcohol draws water from the stomach in order to be digested properly, and will thus dehydrate you further.