How Eating Less Salt Affects Your Body When Exercising in the Heat
Restricting dietary sodium reduces plasma sodium response to exercise in the heat
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Nine fit men ate either low-salt or high-salt diets for 9 days and then cycled in the heat. They drank water to match how much they sweated. The ones on low salt had lower sodium in their blood, higher heart rates, and got hotter, even though they drank the same amount.
Surprising Findings
Sweat sodium did not differ between diets, despite large changes in plasma and urine sodium.
Many assume that low dietary sodium leads to lower sweat sodium, helping the body conserve salt. But here, sweat [Na⁺] was unchanged (54.5 ± 40 vs 54.5 ± 23 mmol/L, P = 0.99), meaning the body didn’t reduce sodium loss through sweat—even on a low-salt diet.
Practical Takeaways
Endurance athletes training in hot climates should ensure adequate sodium intake over several days before intense sessions to support thermoregulation.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Nine fit men ate either low-salt or high-salt diets for 9 days and then cycled in the heat. They drank water to match how much they sweated. The ones on low salt had lower sodium in their blood, higher heart rates, and got hotter, even though they drank the same amount.
Surprising Findings
Sweat sodium did not differ between diets, despite large changes in plasma and urine sodium.
Many assume that low dietary sodium leads to lower sweat sodium, helping the body conserve salt. But here, sweat [Na⁺] was unchanged (54.5 ± 40 vs 54.5 ± 23 mmol/L, P = 0.99), meaning the body didn’t reduce sodium loss through sweat—even on a low-salt diet.
Practical Takeaways
Endurance athletes training in hot climates should ensure adequate sodium intake over several days before intense sessions to support thermoregulation.
Publication
Journal
Scandinavian Journal of Medicine & Science in Sports
Year
2017
Authors
E. Koenders, C. Franken, J. Cotter, S. N. Thornton, N. Rehrer
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Claims (3)
If endurance-trained guys eat less salt for 9 days, their blood sodium drops — even if they drink enough water — especially when they bike in the heat. This suggests long-term salt intake might affect how their body handles hydration in hot weather.
If fit guys eat a low-salt diet for 9 days, their bodies heat up more and their hearts beat faster when they bike in the heat — even if they drink the same amount of fluids — suggesting their bodies aren’t cooling as well.
If fit guys cut down on salt for 9 days, they pee out less sodium—even when exercising in the heat—showing their bodies are adjusting and they’re sticking to the low-salt plan.