To most of us water seems to be one of those things we take for granted and that we only take if were really thirsty. We often substitute water for liquids we find more palatable; fizzy juices, pure fruit juice, concentrated juice, milk or whatever. Some find water too ‘boring’ on its on and drinking enough to satisfy the thirst makes them feel bloated. Too few of us take adequate amounts of water and also too few of us appreciate the health giving benefits of a fully hydrated body; It is not called “the giver of life” for nothing. This section will hopefully make you more aware of the vital role water plays within our body’s, guide you to how much you should be taking and also cover some of the common terms that are associated with the many rehydration products that are available.
Water helps nearly every part of the human body function. Our bodies are approx. 66% water, so understanding water’s important role in the body is a great way of improving your health.
Some important facts to remember:
The brain is 75% water and even moderate dehydration can cause headaches and dizziness.
Water helps regulate our body temperature.
Water is the train that delivers nutrients and oxygen to all cells in the body, it helps the body absorb these nutrients and helps remove waste.
Our blood is approx. 92% water, bones approx. 22% water and muscles approx. 75% water
Water moistens oxygen for us to breath
Water is a natural diuretic; if you drink adequate amounts, frequently there is no need for the body to store it and so subcutaneous water level is low, helping you look tight and vascular.
Water protects and cushions vital organs and also cushions joints
Water is involved in mechanisms which convert our food into energy.
Post-Exercise Rehydration; Is Water The Best Choice?
Most people who take their training seriously are now aware that consuming fluids frequently is crucial to maintaining performance and aiding recovery. But the choice of drink can be critical. So which is best, plain water or a specially-formulated sports drink? To answer that question we need to understand how water is absorbed and used by the body. The rate at which your body absorbs water depends on a number of factors, one of the most important is the fluid composition. It is the concentration of particles such as carbohydrate and sodium (and, to a lesser extent, potassium) that dictates the rate of absorption in the small intestine. As a rule, the higher the carbohydrate content of a drink the slower the rate of fluid uptake.
Your choice of carbohydrate content would depend on whether your primary aim was rehydration or the replenishment of energy stores. Immediately before exercise, rehydration to maintain fluid balance would be a priority (especially in a hot and/or humid environment) as sweat loss will be high. In this instance plain water or a drink which is less concentrated than body fluids (hypotonic) will lead to the most rapid fluid uptake.
However, post-workout, replacing lost fluids is not the only factor to consider when attempting to re-establish fluid balance. Restoring electrolytes such as sodium lost during exercise is important if fluid balance is to be maintained once re-established. Water and some specially-formulated drinks that contain little or no sodium will allow adequate levels of hydration to be maintained after exercise only for relatively short periods. This is because drinking large volumes of plain water or drinks with no electrolyte content over a short period results in a rise in plasma volume, a fall in both sodium concentration and ‘osmolality’ (concentration of particles) of the blood, thus making the blood more dilute. This dilution can lead to an increase in urine production, leading to a loss of body fluids which counteract the effects of rehydration! In addition, the fall in plasma osmolality and sodium concentration can reduce the feeling of needing to drink, which again works against complete rehydration. The logical conclusion must be that where sweat rates are high and losses of body fluids substantial, a drink with no carbohydrate/electrolyte content is not the best way to re-establish fluid balance. We can therefore look to the range of a specially-formulated drinks to help promote a more rapid recovery.
The 3 Categories of Sports Drinks
These drinks fall into three categories, which play different roles in the recovery process and therefore should be consumed at different times after exercise.
Hypotonic drinks are dilute carbohydrate/electrolyte solutions which are less concentrated than body fluids and are therefore rapidly absorbed by the body. They begin the rehydration process while simultaneously helping to replenish carbohydrate energy reserves.
Isotonic drinks have a similar carbohydrate/electrolyte concentration to the body’s own fluids. They are best used later in the recovery process to boost energy intake while still encouraging fluid uptake during the final stages of rehydration.
Hypertonic drinks are solutions with a higher carbohydrate/electrolyte concentration than body fluids. In general these types of drinks contain large amounts of carbohydrate and are therefore best used as energy supplements during periods of heavy training, when energy expenditure is likely to be high.
However, if you prefer to drink water alone after exercise, it is still possible to achieve adequate rehydration if solid food which replaces lost electrolytes is consumed at the same time. If this is not possible, some form of electrolyte solution is essential.
This does not mean you should never drink water after exercise, just that you need to take account of your levels of fluid and electrolyte losses. Where losses are high and large volumes of fluid need to be consumed in a short period, it is important to consume sodium in combination with fluids if fluid balance is to be achieved and maintained.
How Much Water Should I Consume?
Daily water needs are formally based on how many calories you take in. It is recommended that you consume at least 1 litre/1000 Calories.
Below is an extract by Leroy R. Perry entitled “Think You’re drinking enough water?”, it may be a bit repetitive to what was already said but reading it will still do one good. Following it is another article by Danny Kingsley entitled “Too Much Water During Exercise Can kill!”, which we believe you will find interesting;
Think You’re Drinking Enough Water?
If you’re not, you could end up with excess body fat, poor muscle tone, digestive complications, muscle soreness, even water-retention problems.
Next to air, water is the element most necessary for survival. A normal adult is 60 to 70 percent water. We can go without food for almost two months, but without water only a few days. Yet most people have no idea how much water they should drink. In fact, many live in a dehydrated state.
Without water, we’d be poisoned to death by our own waste products. When the kidneys remove uric acid and urea, these must be dissolved in water. If there isn’t enough water, wastes are not removed as effectively and may build up as kidney stones. Water also is vital for chemical reactions in digestion and metabolism. It carries nutrients and oxygen to the cells through the blood and helps to cool the body through perspiration. Water also lubricates our joints.
We even need water to breathe: our lungs must be moist to take in oxygen and excrete carbon dioxide. It is possible to lose a pint of liquid each day just exhaling.
So if you don’t drink sufficient water, you can impair every aspect of your physiology. Dr. Howard Flaks, a bariatric (obesity) specialist in Beverly Hills, Calif, says, “By not drinking enough water, many people incur excess body fat, poor muscle tone and size, decreased digestive efficiency and organ function, increased toxicity in the body, joint and muscle soreness and water retention.”
Water retention? If you’re not drinking enough, your body may retain water to compensate. Paradoxically, fluid retention can sometimes be eliminated by drinking more water, not less.
“Proper water intake is a key to weight loss,” says Dr. Donald Robertson, medical director of the Southwest Bariatric Nutrition Centre in Scottsdale, Arizona. “If people who are trying to lose weight don’t drink enough water, the body can’t metabolise the fat adequately. Retaining fluid also keeps weight up.”
The minimum for a healthy person is eight to ten eight-ounce glasses a day,” says Dr. Flaks. “You need more if you exercise a lot or live in a hot climate. And overweight people should drink in an extra glass for every 25 pounds they exceed their ideal weight. Consult your own physician for their recommendations.
At the International Sports Medicine Institute, we have a formula for daily water intake: 1/2 ounce per pound of body weight if you’re not active (that’s ten eight-ounce glasses if you weigh 160 pounds), and 2/3 ounce per pound if you’re athletic (13 to 14 glasses a day, at the same weight).
Your intake should be spread throughout the day and evening. You may wonder: If I drink this much, won’t I constantly be running to the bathroom? Yes. But after a few weeks, your bladder tends to adjust and you urinate less frequently but in larger amounts.
And by consuming those eight to ten glasses of water throughout the day, you could be on your way to a healthier, leaner body.
Too Much Water During Exercise Can kill!
ABC Science Online
Friday, 18 July 2003
Fluid intake during exercise is essential, but can be overdone. Drinking too much fluid when exercising vigorously, often recommended in training, can actually kill you, sports medicine experts have warned.
“Perhaps the best advice is that drinking according to the personal dictates of thirst seems to be safe and effective,” said Professor Timothy Noakes of South Africa’s Sports Science Institute in an editorial in today’s British Medical Journal. Noakes, also a specialist in human biology at the University of Cape Town, said that much of the conventional understanding about water consumption during exercise is not based on evidence, and that drinking too much is unnecessary and can be fatal.
He cites the example last year, when a woman in the Boston marathon in the United States died from hyponatraemic encephalopathy (a severe lack of salt in the blood) because she ingested excessive volumes of a sports drink before and during the race. But her death was not an isolated incident. Shortly after a doctrine which encouraged those in training to drink the maximum amount they can tolerate became popular, 250 reports of the hyponatraemic encephalopathy appeared in medical literature, Noakes said. The cases were occurring in athletes, army personnel and hikers, and seven were fatalities.
The guidelines currently used for the amount of fluid athletes should drink are not based on evidence, and make several assumptions, Noakes noted. One is that all the weight lost during exercise must be replaced for optimum health and performance. But this ignores the fact that a resting human is able to carry a fluid reserve of about two litres. Conventional thinking has also been that thirst is not a good indicator of how much fluid we need, and is actually a late signal of severe fluid loss. This, combined with the assumption that athletes are similar enough that universal guidelines can be made, has led to doctrines where athletes are encouraged to drink more than they want to. For example, the Australian government’s peak sports science body, Sports Medicine Australia, suggests on its website that athletes drink plenty of fluids several hours before exercising, have at least 500 ml half an hour before a game, 200 ml every 15 minutes during a game and at least 500 ml after a game. A new set of guidelines modelled on evidence-based research have been developed, and have recently been adopted by USA Track and Field, Noakes said. He said the average person should probably be drinking between 400 ml and 800 ml in an hour in most forms of recreational and competitive exercise. People gently exercising in a mild environment would probably need less, and professional athletes competing in warm environments at higher intensities would probably need more.
Drinks that are cool are absorbed more readily by the exercising body than warm drinks, and those containing sodium, such as sports drinks, are also more quickly absorbed.
We hope now you will be more conscious about your water and electrolyte intake. We will end this section by saying that a quick and easy way to see if your adequately hydrated (but not accounting for electrolytes) is by looking at the colour of your urine. Try always make sure its quite clear and not a dark yellow, if you do this from now on you will honestly feel vibrant, alert, happy and healthy.