Beware: Too Much Water Can Be Dangerous By Keith Mulvihill
NEW YORK (Reuters Health) -
Marathon runners consuming copious amounts of water
to avoid dehydration during their 26-mile run should know
that too much of a good thing can lead to illness.
Twenty-one runners out of the 5,082 race finishers of
the 2000 Houston Marathon developed hyponatremia, a condition
in which the sodium concentration in the blood drops because
there is too much water in the bloodstream and an inadequate
excretion of water in urine.
``This represents the highest incidence of hyponatremia
reported following a 26-mile marathon,'' according to
Dr. Jon Divine of the Memorial Hermann Healthcare Organization
in Houston, Texas, and colleagues.
Fourteen of these runners had significant hyponatremia
and required hospitalization, the researchers report.
Divine and his co-authors presented the results of this
study earlier this year at the Joint Annual Meeting of
the American Medical Society for Sports Medicine and American
Osteopathic Academy of Sports Medicine, held in San Antonio,
The investigators found that the longer it took runners
to finish the marathon, the more likely they were to experience
hyponatremia, especially in slower runners with finish
times that exceeded 4 hours and 20 minutes.
Excessive exercise and drinking large amounts of water
can lead to steep falls in blood levels of circulating
electrolytes (salts), which are essential for many body
processes. Symptoms of hyponatremia can include fatigue,
confusion, dizziness and, in extreme cases, coma.
Exercise itself releases an antidiuretic hormone and
slows blood flow to the kidneys--reducing urine output.
``This is a serious condition that causes deaths at many
marathons throughout the world,'' Dr. Lewis Maharam, the
medical director of the New York City Marathon, told Reuters
Health in an interview.
``We don't know exactly how many runners develop hyponatremia,
but as marathons change, it is becoming more common,''
In the past, the majority of people who ran marathons
were experienced runners, Maharam noted. Now, many of
the runners are often novice runners who are primarily
interested in supporting the particular charity that is
associated with the run, he explained.
``The 'charity-runner' is much more likely to stop at
water stations at each mile along the 26-mile route consuming
a cup or two of water because they were told they could
get dehydrated running the race,'' Maharam told Reuters
Health. ''Elite marathon runners on the other hand may
consume water only one time during the race.''
To strike a healthy balance, Maharam suggests that runners
should only drink water when they think they need it,
or if they are sweating more than usual, for example,
on a hot and humid day.
Maharam also recommends that runners should not consume
more than 800 milliliters (about two cups) of water for
each hour they are on the course.
Maharam, who is also president of the New York chapter
of the American College of Sports Medicine and will be
speaking on this topic at their annual meeting this weekend,
notes that women and runners who are on the course for
more than 4 hours are at greatest risk for hyponatremia.
In addition, taking nonsteroidal anti-inflammatory pain
relievers before or during the race also increases a person's
risk for hyponatremia, Maharam warned. ``Runners should
only take acetaminophen before or during a race,'' he
Lastly, Maharam also advises that runners consume salty
food, like pretzels or a salty bagel, as part of their
While no runners where reported to develop hyponatremia
during this month's New York City Marathon, Maharam attributes
that to the fact that registrants have to qualify to be
eligible to run.