Does too much sodium hurt carb absorption? Are runners overdoing electrolytes? I went looking for the research on how much sodium runners need per hour and whether stacking drink mixes, gels, and salt tabs is helping or hurting your fueling.

I was all set to record an episode telling you that too much salt could be wrecking your fueling. Then I went looking for the studies, and they didn't say what I thought they would.

Sodium is actually part of how your body absorbs carbs. The real question is whether your sodium matches how much water you're drinking, and how hot and long the effort is. I walk through the studies on sodium and carb absorption, what happened when cyclists and runners took in 1,200 to 1,500 milligrams of sodium an hour in the heat, why your blood sodium can go up even while you're sweating salt out, why salty drinks can quietly cut into your carbs, whether you need electrolytes every day, and what the research says about cramps. Plus what I do on 12 hour days sweating on a construction site.

I'm not a dietitian or a researcher. This is what I found and what I've experienced, not medical advice. If you have high blood pressure or a heart condition, talk to your doctor before adding salt.

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QUICK CORRECTIONS

In the sodium math example, each of the 2 gels has 250 milligrams of sodium. That plus the 1,000 milligram drink mix is how you get to 1,500 in an hour.

The daily sodium guideline is an upper limit. Most guidelines say to keep it under about 2,300 to 2,400 milligrams a day.

The ACSM range of 460 to 690 milligrams of sodium per liter is a general recommendation, not an optimal number for everyone. Your sweat is yours.

STUDIES MENTIONED

Hargreaves et al. (1994), Medicine & Science in Sports & Exercise. Sodium and glucose absorption during exercise.

Gisolfi et al. (1995), Medicine & Science in Sports & Exercise. Sodium concentration and intestinal absorption.

McCubbin (2025), Performance Nutrition. Sodium intake for athletes review: https://link.springer.com/article/10.1186/s44410-025-00011-9

High vs. low sodium sports drink during 3 hours of cycling in the heat (2022), European Journal of Applied Physiology: https://link.springer.com/article/10.1007/s00421-022-05025-y

McCubbin & Costa (2023), International Journal of Sports Physiology and Performance. Sodium replacement during 5 hours of running in the heat.

Baker et al. (2016), Journal of Sports Sciences (Gatorade Sports Science Institute). Sweat sodium in 506 athletes.

Hoffman et al. (2015). Sodium intake, cramping, and nausea during a 100 mile race.

American College of Sports Medicine (2007). Exercise and Fluid Replacement position stand: https://pubmed.ncbi.nlm.nih.gov/17277604/

CHAPTERS

00:00 Could too much salt be wrecking your fueling?

00:17 Welcome and disclaimer

01:15 Where this idea came from

02:54 Electrolyte basics

03:44 How sodium helps your body absorb carbs

05:05 Does more sodium block carbs? The studies

07:37 Is 1,500 mg of sodium an hour too much?

10:03 Why the sodium to water ratio matters

10:51 How salty is your sweat?

12:03 Blood sodium and the rugby player example

13:21 Is there a magic ratio?

14:13 How salty drinks can hurt your fueling

14:58 Do you need electrolytes every day?

16:44 Sweating 12 hours a day on a construction site

17:30 Sodium and muscle cramps

18:11 5 takeaways

19:44 What I still don't know

20:16 Outro

Until Next Time: Just Keep Running