Why High Endurance Athletes May Require Increased Sodium Intake

by Melinda Burris

This article explores why high endurance athletes must be mindful not only of their hydration levels but also of the amount of sodium they lose through sweating. As is discussed below, the body must maintain a proper sodium balance to function properly. The heightened intensity of high endurance sports puts athletes at increased health risks. Ways to ensure your blood sodium concentration does not dip below proper levels are also discussed.

It has long been recognized that the average American diet is far too high in sodium intake, which frequently contributes to the development of serious health conditions. Hypertension or high blood pressure is commonly attributed to a high sodium diet. In turn, individuals with high blood pressure are at an increased risk for numerous potentially fatal heart conditions, including but not limited to coronary artery disease and heart failure.^1,2

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Because of the associated health risks, the Food and Nutrition Board, the body that sets the Recommended Daily Allowance (RDA) for nutrients in the U.S., suggests a diet low in sodium.^,3  The U.S. Food and Drug Administration (FDA), another government agency, has developed an initiative aimed at working with restaurants and processed food producers to stop the addition of so much sodium to the foods Americans tend to consume. At present, this initiative is voluntary, with the FDA creating industry guidelines with the intent of gradually decreasing the amount of sodium in these popular foods.³

This measure is necessary because on average, Americans consume 3,400 mg of salt each day. However, the RDA for sodium is just 2,300 (mg)—approximately one teaspoon of salt. This means that the majority of Americans consume roughly 50 percent more sodium than they should, risking their health.³

Based on these well-publicized facts, people often assume a diet high in sodium is never beneficial. This may not be true in the case of high endurance athletes. Read on to gain an understanding of why this group of athletes may require a higher amount of sodium per day.²

High endurance athletes must push their bodies harder to meet the intensified demands placed upon their bodies. This intensified level of exertion often causes these athletes to sweat at a higher rate. When we sweat, the body loses sodium, an essential element the body must have to function properly. To maintain the level of performance endurance sports necessitate, participants must replenish the sodium lost through excessive sweating during this type of exercise by maintaining a proper amount of sodium in their systems at all times. Failure to do so can lead to hyponatremia (an unacceptably low level of sodium).¹

High-endurance Athletes and Increased Risk of Hyponatremia

The body requires a proper sodium balance to function properly. Maintenance of a proper sodium level is necessary for the body to send and receive nerve impulses and preserve muscle function.¹ Hyponatremia can also lead to athletes experiencing heat cramps and other illnesses related to overheating.²

The body loses sodium in proportion to the amount at which it sweats. High endurance sports require more intense exertion so naturally, the body sweats more to cool itself down. Light or moderate exercise does not generally require sodium replenishment. Athletes exercising within normal degrees can sustain an adequate hydration level simply by increasing their water consumption.¹

In contrast, high endurance athletes must replace the sodium they are losing with something in addition to water. Science shows that athletes who have diminished sodium levels and hydrate with just water can exacerbate the problem. This is because the more water a person with hyponatremia consumes, the more diluted the concentration of sodium in the blood becomes.¹

Research studies demonstrate that it is not uncommon for high endurance athletes to “lose 1-2 grams of salt per liter of sweat.”¹ The risk of these athletes developing hyponatremia and experiencing diminished nerve transmission and muscle function increases with the duration of exercise. Scientific studies also make it clear that the rate at which a person sweats is individualized, based on their unique physiology. ¹

Athletes competing in high endurance, long-distance sports are at a particular risk of losing an unacceptable amount of sodium. This becomes clear when you understand that these athletes “may lose up to a liter (or more) of sweat each hour.”¹ Extrapolate this hourly loss over the full length of time of an event like a long-distance marathon, and it is understandable that this rate of sodium loss places stress on the body. Concerns over these athletes continually replenishing the sodium lost to avoid hyponatremia is warranted not only to maintain the level of performance competition demands but more importantly, to prevent risks to their health.¹

It stands to reason that athletes competing in hot weather will sweat more as the body has to work harder to cool off. The fact that competitors in the Hawaii Ironman Triathlon often experience diminished blood sodium concentrates demonstrates that the risk of hyponatremia is a real problem that is intensified by competition in warmer climates.¹

It is important to note that much like dehydration, loss of sodium frequently goes unrecognized. Therefore, it is vital that athletes participating in sustained, high endurance exercise maintain an appropriate level of hydration and sodium intake prior to, during, and after exercise or competition is completed to keep the body consistently in balance.²

Ways to Maintain and Replenish Sodium Levels

There are numerous ways athletes can maintain a stable level of sodium concentration in the blood including:

1. Increasing the intake of salt used in food preparation.²
2. Eating healthy, salty snacks such as pretzels, salted popcorn, and trail mix.
3. Drinking sports drinks with salt added.²
4. Dissolving salt tablets in water before drinking it.⁴

Athletes are well served by maintaining a journal of their water and food intake to make sure they are giving their instrument—their body—the nutrients, essential elements (including sodium), and water their body needs consistently. Another important factor to maintain a record of is body weight—before and after exercise. This documentation will allow the athlete, their coach, and trainer to know how much their body typically sweats so they know how much they need to hydrate and if sodium replenishment is necessary in their case.²

References:

1. Quinn, E. (4 March 2020). Salt Needs of Ultra-Endurance Athletes.

2. Verle, V. (August 2007). The Importance of Salt in the Athlete’s Diet.

3.  FDA.gov. (n.d.). You May Be Surprised by How Much Salt You’re Eating.
4. Roland, J. (28 October 2019). What to Know About Salt Tablets.

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