How Much Water Should I Drink?

This is a question that has plagued athletes and the general population for decades. On the whole, research and application regarding this has advanced by leaps and bounds since the days of football practices that included water deprivation and salt tablets. But it is often difficult to get a clear cut response to the question: how much water should I drink? Hopefully this article will give some understandable guidelines.

It should be pointed out that the vast majority of information from this article came from scientific papers from www.ptonthenet.com, an invaluable reference source for Personal Trainers world wide. This information was then disseminated and "streamlined" to make it more to the point and readable for the average fitness aficionado.

The Need for Water

For every 600 calories (kilocalories, actually) of heat loss, the body loses 1 liter of water. If we consider that a typical resting energy expenditure for a woman is 1,200 to 1,500 cal(kcal)/day, that means that she can lose 2-3 liters of water a day just through activities of daily living, not including the added loss from exercise. During intense exercise, water loss can be as much as 2 liters/hour.

Therefore dehydration is a major topic of discussion and should be addressed. Thirst is a poor determinate of the need for fluid intake, so it cannot be relied upon. Also, dehydration can occur very quickly in those who don't take frequent drinks during rigorous activity. So, the best course of action is to make fluid intake automatic and something that is done habitually.

Here are some symptoms and risks of dehydration:

Symptoms:

Urine becomes darker

Small volume of urine

At any given intensity of effort, from rest to exercise, the heart rate is higher than it normally would be.

Performance declines, fatigue occurs more quickly during exercise

Headaches are common.

Risks:

The following illustrates the likely impact on performance and health as dehydration progresses. The measure taken is the percent of weight lost, for instance during a road race. Weight lost during a race or a vigorous day's exercise can be assumed to have come from water. The example is for a 150 pound (2.2 pounds = 1 kilogram) individual.

% of Weight Lost Pounds Lost and Impact on the body
1 1.5lbs; increased body temperature
3 4.5lbs; impaired performance
5 7.5lbs; intestinal problems, heat exhaustion
7 10.5lbs; hallucinations
10 15lbs; circulatory collapse

So, dehydration is something to be avoided. The question comes back: how much water should I drink? Here it is in a nutshell.

Water Intake

According to Dr. Batmanghedlidj of the C.H.E.K Institute a person should drink a minimum of half his or her body weight (in pounds) in ounces of water daily. This seems to be the current, informed agreement for water intake. For example, a 200-pound man would need to drink 100 ounces of water daily. Another way of doing it is to intake 1 ounce per kilogram of bodyweight per day. This is roughly the same (1 pound = 2.2 kilos).

In addition to the minimum amount discussed above just to support activities of daily living, the following recommendations are for water intake in relation to an exercise session. The recommended quantities are given in ounces, 1 cup = 8 ounces, 1 liter = 34 ounces.

Also, it is drastically important to drink plenty of water in the ½ hour to hour after exercise. That's when the repacking of muscle glycogen (stored energy in the form of simple sugars) is occurring at an accelerated rate and it takes 3 grams of water to repack 1 gram of glycogen.

Furthermore, make certain not to drink too much water at any one time since drinking smaller amounts regularly allows more of the water to move from the bloodstream into the cells. Drinking 4 (or more) cups at once causes the blood level to rise so rapidly that the kidneys will filter out more than they will with smaller "doses."

It should be noted that food also contains fluid. This seems like an obvious statement, but when determining daily fluid intake, this tends to be forgotten. It appears to be safe to say that as one calculates fluid intake for the day, he or she can safely omit most foods in determining a total amount. However, foods such as soups could possibly be included.

That covers the primary question. Now, here are some more questions that are frequently asked in relation to fluid consumption, along with the most clear cut answers.

Can I drink too much water?

Most athletes and persons in general will not come close to drinking too much water. The only way "too much" can be determined is the way higher amounts of water intake effect electrolyte levels in the blood steam. The only risk noted, and it is significant, regarding intake of too much water is when one is speaking of ultra-endurance athletes, such as marathoners and great distance travelers. The term for electrolyte imbalances due to excess water consumption is hyponatremia. Along with ultra-endurance cases, hyponatremia has also been observed in summertime hikers in the Grand Canyonand in the military.

The Armed Forces looked at the issue after their medical examiner in Rockville, MDreceived several cases that involved excessive water intake resulting in three deaths. The rapid increase in total body water (TBW) increases the extra cellular fluid, leading to edema. For most tissues this is not an issue, but for the brain, with its limited space for expansion, this edema can lead to hemorrhage, coma and death. Symptoms of hyponatremia include:

Nausea

Dizziness

Vomiting

Seizure

Headache

Confusion

Risk factors for the development of hyponatremia during extreme endurance events include excessive fluid consumption during and after exercise, female gender, NSAID use and slower race times. There was also an inverse relationship between event weight loss and development of hyponatremia. Those with hyponatremia do not always present with obvious symptoms, though disorientation and seizure are strong indicators. If an athlete experiences any of the above symptoms, seeking medical attention quickly is the wisest idea, as the consequences can be deadly.

Time in relation to exercise Amount to drink in cups
2 hours before 2 - 3+ cups
15 minutes before 1 - 2 cups
Every 5 -10 min. during ½ - 1 cups
After Until urine is pale

So, how can an athlete prevent hyponatremia? If pure water is to be used, sticking to the lower end of the American Collegeof Sports Medicine's (ACSM) intake recommendation (20-30 oz./hr) may be a good idea. The simplest remedy would be the use of sports drinks (Gatorade, PowerAde, etc.) rather than pure water for hydration in ultra endurance athletes. In addition to providing fluid, sodium and other electrolytes, they supply performance-maintaining carbohydrate.

Although hyponatremia is not a common condition, it can occur. Most that are partaking in traditional workout activities should be more concerned with dehydration and should perform sufficient intake of fluids accordingly.

For more nutrition and sports related dieting ideas, check out this link.