How Much Sodium Do Athletes Really Need? Modern Science Weighs In (A 2026 Update)

For many athletes, sodium is more than a seasoning on food. It’s a critical electrolyte that drives nerve impulses, supports fluid balance and helps muscles contract. In training and competition, especially in heat or long sessions, the body can lose grams of sodium in sweat. That’s why sodium often appears in sports drinks and electrolyte products. But ten years on from the original HealthCastle article, science offers a clearer, more nuanced view about when athletes actually need extra sodium and when typical diets are sufficient.

Most people know sweat contains sodium. What’s less clear are the conditions under which athletes benefit most from replacing it, and what the science actually says about daily intake versus per-exercise needs.

Sweating and sodium loss

Sodium is the dominant extracellular electrolyte in the body. It helps maintain blood volume and pressure, supports nerve signaling and is essential for muscle contraction. When you sweat, you lose both water and sodium. If fluid losses are not matched, cardiovascular strain increases¹, body temperature regulation becomes harder, and performance drops. In hot or humid conditions, heavy sweat rates can lead to significant sodium and water loss.

Sweat sodium concentration varies widely between athletes. Some “salty sweaters” lose much more sodium per liter of sweat than others. This variability means a one-size-fits-all sodium prescription doesn’t exist. Factors such as heat acclimation, exercise intensity, fitness level and individual physiology all influence sweat rate and sodium content.

Importantly, daily sodium needs for athletes are not higher than for non-athletes² when measured over 24 hours. The kidneys and sweat glands work together to maintain sodium balance, and there’s no strong evidence that training increases daily sodium requirements beyond normal physiological regulation.

When athletes may benefit from extra sodium

There is a practical role for sodium in specific training and competition scenarios:

1. Long endurance exercise and hot conditions. During prolonged sessions (think long runs, races, multi-hour training blocks, or competitions in heat), athletes can lose large quantities of sodium. In marathon or ultra settings, studies³ indicate meaningful sodium replacement may improve fluid balance and delay performance decline.

2. Avoiding exercise-associated hyponatremia (EAH). Drinking too much plain water without sodium during long or hot events can dilute blood sodium and increase risk of hyponatremia. This rare but serious condition affects endurance athletes especially when they prioritize volume of fluid without adequate electrolytes.

3. Helping thirst-driven hydration strategies. Sodium enhances fluid retention and stimulates thirst. Athletes consuming sodium-containing fluids during exercise often find it easier to match fluid losses with intake, especially during events longer than 60 – 90 minutes.

While athletes lose sodium in sweat, the evidence does not support routine high daily sodium intake simply because someone trains hard. What matters most is matching exercise-related losses, not boosting baseline intake.

Practical sodium strategies for training and competition

Here’s what current evidence suggests for real world practice:

Before exercise:

• In temperate conditions and shorter sessions, typical dietary sodium is usually enough.
• In very hot environments, modest sodium intake with food or a sports drink before activity can help fluid retention and reduce early dehydration.

During exercise:

• For sessions under about 90 minutes, plain water and a balanced snack often suffice. If sweat rates are high and sodium losses large, adding a sports drink with electrolytes helps maintain fluid balance.
• For very long sessions (ultra-distance events, extended races), plan sodium and fluid intake based on estimated sweat loss. A rough rule of thumb in applied sports nutrition is to aim for ~300–1000 mg of sodium per hour⁴ in high-sweat conditions, though this varies greatly across individuals.

After exercise:

• Replenish fluids and sodium lost during training with meals and beverages that contain both sodium and carbohydrate.⁵ This supports better fluid retention and quicker recovery.
• Typical food sources like broths, salty snacks, and balanced meals often provide adequate sodium for post-exercise needs.

It’s important to emphasize that sodium replacement during exercise is about supporting hydration and performance in context, not achieving a specific milligram target every day.

1. Armstrong, Lawrence E. “Rehydration during Endurance Exercise: Challenges, Research, Options, Methods.” Nutrientsvol. 13,3 887. 9 Mar. 2021, https://pmc.ncbi.nlm.nih.gov/articles/PMC8001428/
2. Baker, Lindsay B. “Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability.” Sports medicine (Auckland, N.Z.) vol. 47,Suppl 1 (2017): 111-128.
   https://pmc.ncbi.nlm.nih.gov/articles/PMC5371639/
3. McCubbin, Alan J. “Modelling sodium requirements of athletes across a variety of exercise scenarios – Identifying when to test and target, or season to taste.” European journal of sport science vol. 23,6 (2023): 992-1000. https://doi.org/10.1080/17461391.2022.2083526
4. McCubbin, A.J. “Sodium intake for athletes before, during and after exercise: review and recommendations.” Perform. Nutr. 1, 11 (2025). https://doi.org/10.1186/s44410-025-00011-9
5. Ly, Nhu Q et al. “Post-Exercise Rehydration in Athletes: Effects of Sodium and Carbohydrate in Commercial Hydration Beverages.” Nutrients vol. 15,22 4759. 12 Nov. 2023, https://doi.org/10.3390/nu15224759