SALTY DOG

I have noticed an excessive salt taste in my sweat. As I wipe my face during some longer runs, I am expelling a lot of salt. Is this an indication that I’m taking in too much salt (sodium) in my diet? Or is this normal for the time of year (August) and just part of being a long-distance runner?

—Gerard M., via e-mail

OTHER THAN water, salt (aka sodium chloride) is the main nutrient excreted in sweat. Research has shown that individual runners may secrete tremendously different amounts of sweat during the same activity in the heat, and the salt content in the sweat may also vary tremendously.

You may be one of those individuals who excretes a high salt concentration. Also, the salt content in sweat is higher before you become acclimated to running in the heat; after acclimatization, which takes about 7 to 14 days of running in warm temperatures, the salt concentration in sweat decreases tremendously. In the spring, as the temperature warms up, you may notice that when you run, sweat that gets in your eyes may burn, and that’s caused by the high salt concentration. After you’re heat-acclimatized, the sweat no longer burns your eyes, as the salt concentration has diminished.

Normally, your kidneys regulate the salt content of your body in order to maintain normal levels. If they don’t, you may experience high blood pressure if your body retains too much salt (actually sodium), or low blood pressure if your body retains too little. If you eat a balanced diet rich in fruits, vegetables, whole grains, and minimally processed foods, you would not be taking in too much salt. However, if you eat a lot of highly processed foods, which have a high salt content, you may be taking in too much sodium. Check your food labels—they’ll tell you how much a serving of the product contributes to the daily recommendation for salt intake.

During the 7 to 14 days of acclimatization to exercise in the heat, it may be a good idea to sprinkle a little salt on your food if your diet is not normally salt-rich. Also, if you sweat profusely and you still experience the salty taste in your sweat, you may want to continue to use the salt shaker, but not excessively. You may want to have your blood pressure checked. Hope this helps.

Mel Williams
headed the Human Performance Lab at Old Dominion University and is a member of this magazine’s Science Advisory Board.

THE PROPER amount of sodium for a runner is a delicate and complex balance. There is a surprising amount of research on this important subject. Sports nutrition companies that produce electrolyte replacements and sports fluid replacement drinks struggle with this sodium issue. It’s not simply a matter of the amount of salt in your diet. The big picture perspective on sodium for runners relates to a runner’s sodium intake and how it’s used in his or her body.

From a running performance standpoint, sodium is necessary for hydration—that is, for processing the fluid that a runner drinks through the stomach. Many runners attempting to hydrate properly experience the sensation of the fluid sloshing in their stomachs. When this occurs, the fluid is not able to be processed through the stomach, and even though the runner is drinking, he or she isn’t receiving the benefit of the hydration.

When the stomach becomes too full of fluid that can’t be processed, the runner might experience nausea and vomiting. Some of the variables that affect how sodium is used in the body are the environmental conditions that the runner is running in, such as temperature and humidity, and how the sodium metabolism is assisted or prevented due to the fuel or fluid being consumed.

High temperatures and the amount of perspiration (sodium loss) affect sodium levels. Fuels containing high levels of sugar can prevent sodium from being processed through the stomach. Obviously, these variables can change from run to run, so the runner has to understand and manage his or her sodium requirements according to the variables.

To understand what products have the right amounts of sodium for you and the conditions in which you run, read the labels of sports fluid replacement drinks and sodium/electrolyte supplements that you’re considering.

Theresa Daus-Weber
is a 10-time finisher of the Leadville Trail 100, a race that she has also won; she is also a frequent contributor to this magazine.

EXCRETION OF salt, and various other substances in minor amounts, in sweat (predominantly water, which causes the desired skin-cooling effect as it evaporates) is perfectly normal. The amount of sweat produced depends on the extent to which the body senses that it needs cooling. Often sweating is more profuse in summer than in winter because of the higher ambient temperature, but as many of us remember, sweating can be considerable on a cold winter day when running hard in a sweat-suit. In most circumstances, a high dietary salt intake is not necessary for adequate sweat production.

Whether you’re taking in too much salt in your diet is another issue. You may have a good idea about this from your usual intake of high-salt foods, such as salty snacks, most canned soups, and most frozen TV dinners. The labels always state the sodium content. The closer you come to a vegetarian diet, the lower your salt intake is likely to be (vegetable foods contain relatively little salt).

The best way to estimate your usual sodium intake more precisely is by completing daily records of your dietary intake over a time (say, 1 to 4 weeks). A registered dietitian can supply the necessary forms and instructions and also convert the data into an average sodium intake in milligrams per day.

Peter Wood
is the chairman of this magazine’s Science Advisory Board; he has run more than 100 marathons.

ALTHOUGH I claim no scientific knowledge of this subject, from a practical standpoint, I believe the concentration of salt excretion in sweat among athletes is regulated by the body the same way it regulates calorie burning and water retention. What I mean by this is that the body is able to adapt its use of various elements based on conditions it anticipates over the long haul.

A body placed in a starvation mode begins to slow down its metabolism in anticipation of trying to save and more effectively use each calorie available to it. A body regularly deprived of water tends to retain as much water as it can to preserve itself—which is why it isn’t a good idea for people who want to lose weight to restrict their fluid intake: the body sees its deprivation as a crisis and retains fluid, which is just the opposite reaction the dieter wants. Drink plenty of water, and the body excretes any excess.

It’s a similar situation with sodium. If you train in hot temperatures, your body will eventually begin to horde sodium because it knows that for chemical balance purposes, it needs salt and getting rid of it in sweat, which is its normal tendency when there is plenty of sodium available, isn’t a good idea. So, after several weeks of hot-weather training, the salt concentration in your sweat will radically decrease.

When we were training in the desert to run the first-ever Death Valley-to-Mt. Whitney out-and-back in 1989, we’d camp out in the open for a week or more, doing 20-mile workouts during the hottest periods of the day. Various support crew would join us for some or all of the training. After each 20-mile workout, we’d return to camp and lick each other’s arms to determine, based on the salt concentration, whether they were successfully adapting to the hot weather. The saltier the taste of the runner’s sweat, the less adapted they were to the heat.

Rich Benyo
is the editor of this magazine, and on three different occasions (1989, 1991, and 1992) he attempted to travel on foot from Badwater in Death Valley to the peak of Mt. Whitney and back; he has since rid himself of the urge to lick the arms of people he meets.