PFI Online Blog

Hyponatremia (abnormally low levels of sodium in the blood associated with excess water consumption) has received a lot of attention in the media lately, particularly after the article “10 medical myths” was published in the British Medical Journal.  In the article, the authors state that the 8 glasses of water per day standard is a myth created in the 1940’s that gained popularity after it was supported by a well-known nutritionist.  The authors further state that “Existing studies suggest that adequate fluid intake is usually met through typical daily consumption of juice, milk, and even caffeinated beverages.  But drinking excess amounts of water can be dangerous, resulting in water intoxication, hyponatremia, and even death.”   These two sentences have led to a rash of dire reports regarding the “dangers of drinking water”.  What are we to do as fitness professionals?

The truth is that hyponatremia is a very rare condition that develops partially due loss of electrolytes through sweating and through excess rehydration with water only (i.e. no sports drinks!).  Symptoms of hyponatremia include headache, malaise, nausea, and vomiting.  In very rare instances, an individual can develop this condition through consumption of water alone, but the sheer volume of water that the person would have to consume is mind-boggling.  In actuality the risks associated with dehydration after  exhaustive exercise are much more common than those seen with excess hydration after exercise.  The NSCA recommends that athletes rehydrate with 16 oz. of fluid per pound lost during the exercise session.  Other drinks, such as gatorade and powerade, should be considered depending on the specific goals of the client.