hydration
Humans are made up of between 60 - 80% water. Through the day we lose water from our bodies through sweat, exhalation and excretion and if we don't replace it we start to become dehydrated.
When exercising, the rate at which we lose water from our bodies is increased and studies have shown that even a small (2&percent;) drop in body weight through dehydration can cause a significant reduction in performance; 6-7&percent; slower over 5 and 10km
Before exercise
The American College of Sports Medicine (ACSM) recommends consuming about 500ml of fluids about two hours before exercise, and 125-250ml immediately prior to exercise to delay the onset of dehydration.
During exercise
As soon as you start exercising you will start to lose fluids. Aim to drink 125-250ml for every 10-20 minutes of exercise. Studies have shown that you can maintain optimal performance if you replace at least 80&per100; of sweat lost during exercise.
When training, consider taking a drinks bottle with you, especially if the run is going to be longer than half an hour. We recommend the Nathan Elite bottle holder and bottle, which sits around the waist and provides easy access to fluids.
If you are racing, it is advisable to find out what (if any) drinks will be provided along the route.
If you have only ever run with water and then take a sports drink like Lucozade on whilst racing you may find you have an adverse reaction to it.
After exercise
Researchers recommend that you should consume at least the equivalent of 1.5 times the fluid lost during exercise.
You can work out roughly how much you lose during a run by weighing youself before and after and taking one away from the other (remember to take into consideration any fluids you consumed during the run).
Work on the basis that 1kg lost body weight is about 1 litre of fluids. Don't drink all this fluid straight away, but aim to consume it within about an hour of finishing your run.
What should I drink?
Water should be your drink of choice for most occasions, but you may also want to take on a carbohydrate based sports drink. There are many on the market, but Run Republic recommends the Maxim Energy drink. It comes in sachet form and is easily disolved in water.
Carbohydrate drinks work on two levels. Firstly, they provide a source of quick release energy that will be rapidly absorbed into the blood stream and taken to the working muscles. Secondly, sports drinks are hypotonic which means their concentration (parts per million) is greater than that of the body's fluids. This has the effect of allowing the fluid to be more readily absorbed by the body, increasing the rehydration rate. Sports drinks such as Maxim Energy Drink also contain electrolytes (mineral salts such as sodium, potassium, chloride and magnesium) to replace those lost through sweat.
What is the difference between hypertonic, isotonic and hypotonic?
Hypotonic drinks have a lower concentration of particles than the body's fluids and so it can be absorbed faster than plain water.
Isotonic drinks have the same concentration as the body's particles and so are absorbed at about the same rate as water. Isotonic drinks generally provide the best balance between rehydration and refuelling.
Hypertonic drinks have a higher concentration of particles than the body's fluids and so are absorbed slower than plain water. These sort of drinks are not very good for rehydration but are useful for refuelling after a run.