Hydration is essential. That much we know. As the temperature rises in the summer, it is even more essential -- especially if you take your workouts outdoors. The general recommendation is 2 litres a day but exercise and heat increase your body's demand for fluids. Our bodies rely on chemical reactions to function and what we require for these reactions is contained in a fluid solution. If you have a reduction in fluid, the proper materials cannot get where they are going to initiate these chemical reactions. If you lose just 2% of your fluid, your performance can start to suffer 10-20%. If you don't have enough water in your system, you won't perspire (one of your body's methods for cooling off) which can lead to fatigue or a rise in your inner temperature which if not corrected, could spell disaster. How much do you need to drink? The general rule is to drink 500ml per hour of rigorous exercise (on top of the 2 litres a day) but as with most things, it can vary person to person. For best results, calculate your needs yourself. One litre of water weighs one kilogram. By measuring your weight before and after training or a test event and correcting for any fluids taken in, you will get an individual rate of fluid lost for those conditions. When should you drink? Keeping yourself hydrated starts long before your training session or event. It is likely that when you wake up in the morning you are a little dehydrated so start there. It is important to drink as soon as you get up. If you are doing a long event or training session, try sipping as you go. Set a timer to go off every 15 mins and take a drink when the alarm sounds. Otherwise, you may find that time just flies by and before you know it, you're in trouble. When you are finished, you should drink again. You are probably a little dehydrated so an increase in fluid can help there but it can also help flush your body of metabolic waste. Remember: different fluids are absorbed at different rates depending on their concentration. According to cyclist, trainer and sports massage therapist, Simon Kidd:
Osmosis is a process where water will move from a more concentrated solution to a lower concentrated solution across a boundary.
- Hypotonic: Has a concentration that is lower than the body and will be absorbed quickly. This is a good mixture when fluid loss is likely to occur at a high rate.
- Hypertonic: Has a concentration higher than the body. This is slower to digest and a very concentrated solution may result in water being drawn out from the body. This is undesirable in situations where we are trying to rehydrate the body. This mixture often occurs by mixing sports drinks with too much powder by mistake.
- Isotonic: Has the same concentration as the body and can be readily absorbed. This is a good concentration to maximize transport of electrolytes or carbohydrates.