Sodium’s Role in Endurance Sports – Primer on Common Issues

As the world gets hotter, some factors in endurance sports grow in importance. One of those factors is hydration and its sidekick “proper electrolyte balance.” Most runners know the basic rule – if you want to run far you should take in some salt (and maybe potassium) along with ample water or you’ll cramp up. It’s true that if you’re going to run far (or bike, or hike), especially in warm conditions, you will sweat out key electrolytes faster than your body can resupply them. When electrolytes fall out of balance within our bodies, we’re unable to perform at optimal level.

For this article, i did a little research to take my understanding of the role of Sodium a little higher. I dove into articles by sports nutritionists, and I dug into nurse training articles about how to recognize and treat electrolyte imbalance in their patients. I share my findings with you here.

Electrolyte primer by Runivore

What are Electrolytes and Why Do They Matter?

Let’s start with some facts about what we are? We are mostly water, in fact 70% of our bodies are made up of water, when we look at our brain – it is 90% water, muscles are 73% water, blood is 83% water, even our bones are 22% water. One key function of the liquid is to help transport oxygen and nutrients into the cells that help us maintain life. This fluid is not just plain water, it consists of many things and one of those things are electrolytes. There are 6 main electrolytes: potassium, sodium, chloride, calcium, phosphate, and magnesium, in this article we’ll focus on sodium.

What’s the key function of electrolytes?

Electrolytes are substances that when dissolved in our blood produce an electrical charge, hence become ions. They then become enablers of key functions within our body such as electrical signaling, help with contraction of muscles, sending nerve impulses, balancing the fluids in our body via osmosis, and maintaining the blood’s acid base balance.

In order for them to function properly they must be at just the right quantity within our body. Abnormalities associated with the key functions listed above start occurring if we have imbalances of electrolytes. These abnormalities include: fatigue, muscle spasms, and even heart arrhythmia.

How do we get electrolytes into our bodies?

We get the majority of our electrolytes from our food and drinks. They get absorbed in our gut and goes into our blood. Our blood is constantly filtered by our kidneys and it is the kidneys that regulate the quantities of electrolytes within our body, by either keeping them in our blood or releasing excess electrolytes into our urine. Something to be aware of here, if you have gut or kidney problems — you may be more susceptible to electrolyte abnormalities.

Let’s take a closer look at sodium and common abnormalities that may occur if it gets out of balance.

Runners’ favorite electrolyte – sodium

Sodium plays a huge role in regulating the water inside and outside our cells along with muscle contraction and nerve impulses. So if you get an imbalance of sodium in your body you’re going to see issues with these processes. Those processes are pretty key to optimal performance in endurance sports, and that’s why sodium is the most talked about electrolyte by endurance athletes – there is even a company called SaltStick that provides anti-sodium deficiency solutions for athletes. The normal sodium level that should be in your body is specified at 135-145mEq/L. The greater that you are out of this range the more profound the symptoms that you may experience.

If your sodium level is too high, you may experience hypernatremia. You should remember that water loves sodium, so when there is a higher than normal concentration of sodium in your blood, it is going to suck water of cells and in effect shrink the cells. Things that might cause your sodium level to be too high are hormone issues, and more relevant for runners: over consumption or not drinking enough water.

The symptoms associated with high sodium levels are especially not ideal for runners and they include: Fatigue, Restlessness, Increased reflexes,  Extreme thirst, and Decreased urine output or dry skin. One of the nurse articles highlighted that the first letters of those symptoms spell out FRIED making it easy to remember.

On the other hand if the sodium concentration is too low in your blood it is going to cause your cells to swell – this condition is known as hyponatremia. Neither shrinking or swelling cells are good for you. The causes of low sodium are: not consuming enough of it, as well as diarrhea, or vomiting.

The symptoms have a mnemonic device associated with it as well. If you remember the word SALT LOSS, you will remember the symptoms: Seizures and Stupor, Abdominal cramping, Lethargy, Tendon reflexes diminished and trouble concentrating, Loss of urine and appetite, Overactive bowel sounds, Shallow respiration, and our most known enemy Spasms of muscles. In other words symptoms that range in seriousness from discomfort to life threatening conditions.

The key take away is – make sure to take in plenty of salts as you take on your endurance adventures. In our next electrolyte article, we’ll take a look the flip side of sodium – potassium. Until then, stay tuned and stay hydrated.