by Cassie Bjork in Health + Nutrition, image by Kristian Niemi

Sodium for Runners

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As athletes, we are well aware that we lose salt in our sweat. It stings when we get it in our eyes and we can taste it when it ever-so-gently drips onto our lips. Our sports drinks boast that they provide electrolytes, including sodium of course. So are we getting enough? How do we know how much sodium is required? And is it possible to damage our bodies with a sodium overdose?

With hypertension (high blood pressure) on the rise in our country, as a Registered Dietitian, I am often stressing the importance of reducing sodium intake, which is of high priority for most Americans. However, low sodium levels are just as dangerous as high sodium levels. Runners need to be especially aware of this, as well as anyone that exercises regularly. Salt plays a role in numerous physiological aspects that relate to running performance, including working with potassium to maintain fluid balance, preventing cramping and hyponatremia (an abnormal level of sodium in the blood caused by excessive water diluting the sodium outside the cells.) Hyponatremia is particularly a concern for athletes exercising for more than four hours—which means the greatest risk for runners participating in marathons, ultramarathons and triathletes. Common symptoms of hyponatremia are confusion, fatigue, headache, muscle cramps, nausea and bloating. Severe complications can include seizure, coma and death. As you can see, it’s clearly a serious condition and runners should constantly take preventative measures to avoid it.

What can I do to prevent this?

Both dehydration and overhydration are serious concerns for athletes, which poses the dilemma of finding the proper balance. The key is to learn your own sweat rate because each individual is different. This can be done by weighing yourself before and after you run. The amount of weight you lose is equivalent to the amount of fluid you will need to replace. For example, if your post-run weight is down one pound (one pound is equivalent to 16 ounces), you will need to drink 16 ounces of fluid to replace what you’ve lost. Knowing your own sweat rate gives you a clear idea of how much fluid you need so that you are less prone to overhydrating. A quick hydration assessment can be done by noticing the color of your urine. If you are well hydrated, it should be light in color, like lemonade. If you are not properly hydrated it will appear dark in color, such as apple juice. If this is the case, focus on having more water and less caffeine (which has a diuretic, dehydrating effect.) As far as sodium is concerned, it’s much more difficult to assess how much sodium is lost than fluid. Sports drinks are more effective than plain water in helping the body maintain this balance because they replace both fluid and salt. When we replenish with just water, it dilutes the sodium balance in our body which can lead to abovementioned (and dreaded) hyponatremia. As a result, it is certainly wise to hydrate with sports drinks when participating in prolonged activity (i.e. running greater than one hour,) or even alternate between water and a sports drink.

Additional tips to help your body maintain a healthy sodium balance

  • An hour or two before your run, aim to drink 16 ounces of fluid along with a salty snack to build up your body’s sodium stores (e.g. pretzels, soup, cheese.)
  • Drink a small amount of fluid immediately before starting your run (4-8 ounces is a good benchmark) and small amounts of fluid during your run (a good rule of thumb is 4-6 ounces every 20 minutes.) Be careful not to overdo it.
  • During your run, if you start to feel any of the symptoms of hyponatremia (mentioned above,) stop all activity and seek medical help immediately.
  • After the run, it is wise to reach for a salty snack, such as a cheese or turkey sandwich, pretzels or pickles and wash it down with water—two cups for every pound lost in sweat.

There’s no need to stress out about sodium, but it is wise to understand symptoms of hyponatremia. I encourage you to take preventative measures by incorporating some or all of the above tips into your running routine!




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