Why is sodium critical to athlete performance?
Sodium plays a key role in your body's functions, helping to maintain fluid balance and cognitive function. That's why it's important to replace the sodium you lose to some degree when your sweat losses really start to increase sharply.
Why sodium is important.
A study from 2015 found that athletes who adequately replaced the sodium they lost through sweat finished a middle-distance triathlon an average of 26 minutes faster than those who didn't.
While this type of performance improvement may not be possible for everyone, it demonstrates the impact that proper hydration can have.
Your body contains a lot of water - depending on the amount of muscle and fat, it is made up of 50% to 70% of this substance. About one-third of this water is outside your cells, in extracellular fluids such as your blood.
What does sodium do?
The main electrolyte in this extracellular fluid is sodium, and much of your body's total sodium reserves are found here. This makes it quite "salty" and the total volume of extracellular fluid in your body is directly related to the amount of sodium you have on board at any given time. So more sodium means more fluid, less sodium means less fluid.
In addition to regulating fluid balance, sodium plays an important role in the absorption of nutrients in the intestines, the maintenance of cognitive function, the transmission of nerve impulses, and muscle contraction. Basically, it's pretty darn important.
Most of the sodium we consume is in the form of sodium chloride, the common table salt found in food and drink.
Nowadays, we take salt for granted because we have developed ways to make it available everywhere. But in the past, wars were fought over access to and control of salt, which gives you a pretty good indication of its importance to life!
Because your body can only produce or store salt up to a certain point, you need to consume sodium daily to maintain your levels.
There are individual differences as athletes primarily lose sodium and fluid during exercise. For this reason, those who exercise regularly have a different need for sodium.
Everyone loses a different amount of sodium with sweat. At le melo, we see athletes losing anywhere from 200 mg of sodium per liter of sweat to as much as 2,000 mg/l. Personally, I lose ~1,800 mg/l and therefore often suffered from hydration problems in hot climates (I am frequently in Turkey and Portugal). It was my personal search for a solution that led me to start the company.
The amount of sweat also varies, of course, from person to person and situation to situation (from almost nothing in cooler conditions and low intensity to several liters per hour in intense exercise in the heat).
When you combine the differences in sodium concentration with the differences in sweat rate, the potential differences in net sodium losses between individual athletes can be very large, especially in a middle- or long-distance triathlon.
And in many cases, these losses are many times greater than someone who does not sweat regularly. That's why athletes should take the standard government guidelines for sodium consumption with a grain of salt. If you sweat profusely and sweat out a lot of sodium, it is more than possible to lose the 2,300 mg of sodium per day recommended in the government guidelines in just one hour of exercise. With prolonged exercise, the loss can be truly enormous.
What happens when sodium losses increase?
It's impossible to pinpoint the exact point at which sodium (and fluid) loss through sweating becomes a problem for an athlete. What is clear, however, is that beyond a certain point, losses can adversely affect your performance.
Your blood volume gradually decreases as your sweat losses increase. This is because sweat is removed from the blood plasma. This puts more strain on your cardiovascular system and makes it harder to pump blood to cool your skin and working muscles.
Other problems, such as a general feeling of fatigue and muscle cramps, can occur if the losses go uncorrected long enough, or if there is a significant imbalance between fluid and sodium.
Until a certain point, simply drinking water is enough to compensate for sweat loss. But as those losses increase, you'll also need to replace sodium so your blood doesn't get diluted.
This is a potentially catastrophic condition called hyponatremia, which can ruin your race and, tragically, is sometimes fatal.
How much sodium should you replace when you sweat?
Since sweat/sodium losses are so individual, general guidelines for sodium and fluid replacement should always be taken with a grain of salt.
However, if you find out whether your net losses tend to be low, moderate, or high, that's a good starting point for determining the amount of sodium and fluid that's best for you under different circumstances.
The two most important factors that determine your personal net sodium loss are....
- The total amount you sweat. It depends on your sweat rate and the number of hours you sweat within a given period of time.
- Your sodium concentration in sweat, that is, how much salt you lose through your sweat.
To find out roughly what these values are, it's a good idea to start there.
Calculating your sweat rate can be a bit cumbersome, but here's a guide to help you get a reasonable estimate of how much you sweat per hour.
The sodium concentration in your sweat is largely genetic and varies very little. That means you can only find out by taking a sweat test, but in most cases you'll only need to have it done once.
Bestzeit offers a non-invasive sweat test that you can use to find out exactly how much you're losing. → https://sweatpack.bestzeit.com/