[note hyponatremia tends to be less of a problem for fast enurance
runners. Why? The profile for this person is that he or she is not
spending time stopping and gulping lots of fluids. This person is out
in the sun for a relatively short time - exposed to the sun, sweating
salts and drinking fluids. The problem often arises in the very slow
runners, who carry their own water and drink at every water stop and
are out for a longer period of time in harsh temps., etc. Again,
moderation is important. In training, it is often a question of not
whether you can but whether you should. So you undertrain, overtrain,
over drink. Moderation. -Coach Bob]


By Matt Fitzgerald
For Active.com
September 19, 2005

Every endurance athlete knows that sweat is salty. That's why sports
drinks contain salt (i.e. sodium). By replacing both the water and the
salt you lose in sweat, sports drinks do a better job than plain water
of keeping your body temperature down and your performance level up.

There's a debate, however, about whether the typical sports drink
contains enough salt. The typical sports drinks contains less salt
than sweat does, so it can't fully replace the salt lost through sweating.

Some experts believe that this discrepancy poses no threat to the
athlete's performance or health. Others believe that it does, and
advocate the use of salt supplements such as Lava Salts® and/or
extra-salty sports drinks such as Gatorade Endurance Formula® during
prolonged exercise.

Who's right? Do runners really need to fully replace salt losses
during long workouts and races? A quick look at the relevant research
answers this question easily. The evidence clearly demonstrates that a
typical sports drink provides enough salt to optimize performance and
protect the athlete's health, provided he or she doesn't overdrink.
There's no measurable benefit associated with consuming extra salt.
Let's look at some of the details.

Optimizing hydration

Sodium is said to assist hydration in two ways. First, it's believed
to increase the rate of fluid absorption from the gut into the
bloodstream. And faster fluid absorption means faster hydration and
less dehydration.

However, according to a pair of studies from the University of Iowa,
sodium only increases the rate of fluid absorption if the fluid
doesn't also contain carbohydrate. If the fluid does contain
carbohydrate -- as most sports drinks do -- the amount of sodium
contained in the drink (or consumed with the drink, in the case of
salt tablets) has no effect on the absorption rate. The carbohydrate
itself maximizes the rate of fluid absorption.

The second purported benefit of sodium with regard to hydration is
that it helps athletes maintain a higher blood volume, which in turn
keeps body temperature and heart rate from rising during prolonged
exercise. Research has shown that sodium does indeed have these
effects. However, a South African study found that a high-sodium
sports drink was no more effective than a low-sodium sports drink in
regulating body temperature and preventing "cardiac drift" (rising
heart rate during prolonged exercise).

What can we conclude from these results? You don't need to consume as
much sodium as you lose in sweat to keep your blood volume up and your
temperature and heart rate down. The amount of sodium found in a
typical sports drink will do the job. Taking in extra salt won't
provide any additional benefit.

Avoiding hyponatremia

The major salt-related risk to the health of runners is hyponatremia,
a potentially fatal condition that has received a lot of attention
lately. Also known as water intoxication, hyponatremia results when
the sodium concentration of the blood falls too low due to prolonged
sweating combined with excessive fluid consumption. Symptoms include
dizziness, muscle cramping, confusion, and stomach bloating. Severe
cases can lead to seizure, coma and even death.

Because hyponatremia is characterized by low salt concentration in the
blood, some experts advocate consuming extra salt during exercise as a
way to prevent it. However, the primary cause of hyponatremia is not
consuming too little salt, but is rather drinking too much fluid.
Therefore the best way to avoid hyponatremia is not to consume more
salt, but to drink less fluid instead.

A recent Swiss study compared the effects of three different fluids --
water, a low-sodium drink and a high-sodium drink -- consumed at a
high rate of one liter per hour -- on the blood sodium levels and
performance of runners in a four-hour run.

Despite the fact that the high-sodium drink contained almost as much
salt as sweat, 46 percent of the study subjects developed mild
hyponatremia when using it. While this percentage was slightly lower
than the percentage of subjects who developed mild hyponatremia when
using the low-sodium sports drink, these results clearly show that
it's hard to avoid diluting your blood, now matter how much salt you
consume, if you overdrink. (The current recommended drinking rate for
runners is 400-800 ml/hr.) It's also worth noting that none of the
three drinks tested in this study had any effect on performance as
compared to the others.

Studies involving salt tablets -- which are popular among
ultra-runners and long-distance triathletes -- have produced similar
results. In a New Zealand study of Ironman participants, salt tablets
were found to be unnecessary to maintain normal blood sodium levels.

The underlying conclusion we can draw from all of the research on salt
intake in endurance events is that the typical sports drink provides
plenty. Salt tablets and extra-salty sports drinks provide no
additional benefits for performance or health protection.

This article was adapted by the author from The Cutting-Edge Runner:
How to Use the Latest Science and Technology to Run Longer, Stronger,
and Faster (Rodale, $15.95). Click here to purchase a copy.