Hydrate for health
Keeping yourself well hydrated is a key consideration for achieving optimal health and maximising exercise performance. Our bodies consist of approximately 60 percent water and a drop of just a few percent can result in adverse symptoms. The reason for this is water is needed to control body temperature as well as for the delivery of nutrients and excretion of wastes. Water also forms the medium in which the body’s many chemical reactions occur.
How do you know if you are hydrated?
Despite common misconception, thirst is actually an imperfect measure of how well hydrated you are. By the time you are thirsty you can be already dehydrated by half a litre or so. Therefore, thirst cannot be relied upon to monitor hydration status. A better way to keep check on your level of hydration is by monitoring urine output. The motto here is, ‘Don’t go for gold!’ When fully hydrated your urine should be clear and odourless – although vitamin B2 can give a bright yellow appearance.
What is the best way to stay hydrated?
On average your body loses approximately 2.5 litres of fluid every day, which equates to around eight glasses or three standard drink bottles, which is why we should aim to drink this much each day. Obviously your fluid requirements increase substantially in hot weather and during times of high activity. During such times your fluid intake should increase accordingly. During exercise fluid loss through sweating is often in the order of 800 millilitres (mL) to 1.4 litres per hour (approximately three to six glasses), although sweat rates of up to three litres per hour have been recorded. It is desirable to match your rate of fluid consumption with your rate of sweating. It’s interesting to note that voluntary drinking only replaces about two-thirds of the body water you lose as sweat. Therefore, making a purposeful attempt to stay hydrated is necessary. For this reason the American College of Sports Medicine (ACSM) recommends that during exercise individuals drink a minimum of 150 mL (just over half a glass) every 15 minutes.
Obviously, in order to keep hydrated you need fluid to be accessible, so be sure to keep a drink bottle on your desk, in the car and with you when you exercise.
What should I drink?
There are a variety of beverages available on the market, so which one should you drink? The answer to this question depends on several factors, including the occasion in which you use them, as well as personal preference. Plain water is always a good hydration option. However, many people find plain water boring as it lacks taste appeal and so they don’t drink as much as they require. If this is the case, drinking a flavoured beverage can provide a greater incentive to keep hydrated. Also, plain water does not replace electrolytes that can be lost in sweat. This may be an important consideration if you are perspiring heavily for a long period of time.
Sports drinks like Gatorade® and Powerade® have been specially formulated to do two things. Firstly, they ‘put back in what the sweat takes out’ which includes water and electrolytes. Secondly, they provide energy for exercise – typically around 150 to 200 calories per bottle. If you are exercising for an extended period of time (e.g., longer than one hour) this energy has been shown to delay fatigue and improve exercise performance. However, if you do not exercise for long periods of time or you exercise to manage your body weight, the calories in sports drinks may not be desirable. For example, it can take 30 minutes or more of walking to burn off the calories in a bottle of sports drink.