Fluid Replacement in Athletes: How Much Is Too Much?
Dec. 17, 1999 (Minneapolis) -- During the last decade, researchers have
learned a lot about fluid replacement in athletes and the importance of
drinking liquids -- before, during, and after strenuous activities. Yet more
recently, scientists have increasingly focused on what happens when too much
fluid is ingested. Recent reports of several athletes who died after
over-hydration have brought the issue into the spotlight.
The life-threatening condition known as hyponatremia occurs when excess
fluids -- ingested orally or intravenously -- cause depletion of sodium in the
body. With the increasing popularity of ultradistance triathlons and Iron Man
events in the 1990s, the incidence of hyponatremia has risen, and the condition
is now under close scrutiny by sports medicine specialists and scientists
around the world.
In a 1999 study, researchers from Winn Army Community Hospital in Fort
Stewart, Ga., reported the first known death of an Army basic trainee as a
result of drinking too much water. When physicians misinterpreted his symptoms
as being dehydration and heat injury, they continued to provide fluids
intravenously -- so much so, that fluid levels overloaded the cells, tissues,
and cavities of his brain and lungs.
Researcher Timothy Noakes, who is with the Bioenergetics of Exercise
Research Unit at the University of Cape Town in South Africa, questions the use
of intravenous fluid therapy in sports. "Must a collapsed marathon runner
or army recruit or football player with muscle cramps die from hyponatremia
before we finally question our ignorance?" he writes in an editorial in the
October issue of British Journal of Sports Medicine.
Sports medicine specialist Douglas Stoddard, MD, of the Toronto Sports and
Exercise Medicine Institute, tells WebMD that the key is not that athletes are
over- or under-hydrated, but that many are under-replenished with sodium and
potassium. He suggests that athletes eat foods that are high in potassium, such
as bananas. Also, he says that it is important to "rehydrate with a fluid
that contains enough sodium and potassium to balance the amounts lost in sweat,
such as the newer sports drinks."
And not all athletes are created equal when it comes to fluid loss and sweat
concentrations, Stoddard adds. "Depending on the volume and the
concentration of sodium and potassium in their sweat, the person can run into
problems that range from nausea, gastrointestinal discomfort, and muscle
cramping to a drop in blood pressure, dizziness, coma, or death," he
With an eye on prevention, the American College of Sports Medicine (ACSM)
says that adequate fluid replacement helps maintain hydration and, therefore,
promotes the health, safety, and optimal physical performance of individuals
participating in regular physical activity. The ACSM's general recommendations
detail the amount and composition of fluid that should be ingested in
preparation for, during, and after exercise or athletic competition.