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article imageMarathoners need to watch overhydration

By Joe Duarte     Feb 11, 2014 in Health
A lot is known about dehydration, how to prevent it and even how to recover from it, but few people know about overhydration, which takes on symptoms of intoxication and can result in comas and death if left untreated.
As detailed by the Associated Press, water intoxication was recently brought to prominence with the arrest and detention of a Tennessee couple in the death of a five-year old girl, who was reportedly forced to drink about 2.5 liters of water and grape soda over a span of two hours. The massive intake of liquid had resulted in her brain’s swelling and the pressure couldn’t be alleviated in time to save her.
The scientific term for water intoxication is hyponatremia, and it doesn’t so much result from having too much water in your system as from not having enough electrolytes in your body to balance the amount of water. In other words, it can result from drinking too much water in too short a period of time, or it can result from sweating too much without replacing sodium ions, or it can also result from the inability to excrete water (either through disease or malnourishment that reduces kidney function).
And though it often results from abusing the intake of water, such as the instance of a California woman who, as part of a 2007 radio contest, died as a result of drinking too much water without urinating, it can also result from excessive sweating without replenishing electrolytes in the system.
A study of a group of Boston Marathon finishers in 2002, for example, revealed that 13 percent had excessively low levels of sodium in their blood, and 0.6 percent were at critical levels.
In the case of extreme sports such as marathons or triathlons, and especially those in held in severe heat, the problem usually arises from taking in water without taking in electrolyte solutions (such as sports drinks). Seasoned triathletes and marathon runners know to balance their water intake with some form of electrolyte solution, but some who are relatively new to the sports aren’t aware that too much of either is a recipe for disaster.
Electrolytes are basically salt ions with a charge (electricity, get it?) and allow the body’s cells to maintain the balance between salts and water (there are more electrolytes inside cells and more water outside of cells). The major electrolytes in your body are sodium, potassium, calcium, magnesium, chloride and phosphate, among others. Every cell in your body relies on these electric impulses to function and therefore relies on a healthy balance of electrolytes. An extreme sodium imbalance in the body, therefore, leads to cell damage and can result in death in extreme cases.
The symptoms of water intoxication are similar to those of alcohol intoxication—altered mental state or headaches, nausea and vomiting (some of which are also associated with dehydration). In extreme cases, water intoxication also manifests itself in loss of muscle function and convulsions.
There is no scientific formula for optimum water/electrolyte intake. Ideally, you want to take as much in as you expel, but that is often unquantifiable because it varies according to body type, size and weight. And although many experts advise people to drink before they feel thirsty, the advice some give marathoners to ensure they don’t dehydrate or overhydrate on their runs is to drink a balance of water and sports drinks when they feel thirsty.
More about hyponatremia, overhydration, Hydration, electrolytes, Marathoner