Marathon Training Sodium
Tip #24

In marathon training sodium should not be taken for granted. Here is a summary of what the experts think and how to plan to consume enough sodium for training and competition.

“The man who does not think and plan long ahead will find trouble right at his door.” Confucius

  • What is the purpose of sodium?

  • In marathon training sodium regulates body fluids (and therefore hydration). Sodium also has a role in muscle contraction (and therefore it has a relationship to cramping). Both of these sodium roles have a direct impact on running performance.

  • How does marathon training sodium impact hydration?

  • If you thought hydration was only about fluids, think again. Sodium regulates fluid balance in the body, so not having enough sodium in the body can throw off that balance. Small changes in hydration can lessen your performance in training or in the race. Dehydration is a danger because your core body temperature increases, thus the problem of “heat illness”. Over-hydration is also a danger due to the low blood sodium levels that accompany this condition. The condition, called hyponatremia, is usually caused by drinking too much fluid, but can also be caused from excessive sodium loss.

    The best advice is to weigh yourself before and after a training session or race. If you lost weight you did not hydrate well. If you gained weight you drank too much. Check your weight all throughout training to get in the groove with your personal hydration and sodium needs.

  • Do marathon training sodium needs differ from the sodium needs of the general population?

  • An endurance athlete needs more sodium compared to a sedentary person (confirmed by the Institute of Medicine who makes recommendations for the entire population). How much sodium is needed is a personalized issue, based on how you sweat. Some athletes are ”salty sweaters”, meaning that they lose more sodium in sweat than most people. This is genetically set and this person needs more sodium. A salty sweater will notice a white film on his clothes and skin after exercise, or he may complain of his eyes burning (due to the saltiness of the sweat running into his eyes) during exercise. Another athlete may not be a salty sweater, but he may sweat heavily. Sweat carries sodium out of the body, so over an extended exercise session a large quantity of sodium is lost from the body. In either case, the athlete needs to replace both the fluid and the sodium. The sodium you need to replace may equate to several teaspoons of salt. Athletes used to training in the heat still need more sodium. Even though the body adapts by losing a lower concentration of sodium, the body also adapts by sweating more…bottom line is that there still is a substantial sodium loss.

  • I thought sodium was related to high blood pressure?

  • Marathon runners do not fit into the same blood pressure recommendations as the general population for several reasons. The sodium level that may cause a sedentary person’s blood pressure to rise is different then the marathon runner’s body that frequently loses sodium in sweat with training. Also, the process of endurance running helps regulate blood pressure, whereas most of the population is sedentary. Marathon training can also be a good stress release. Things other than sodium can raise blood pressure, including excess body weight, a diet low in fruits/vegetables/lowfat dairy, and stress. If you’re unsure what to do, talk to your healthcare provider. It is likely you can control your blood pressure with a healthy diet, weight loss and stress management techniques, while still getting the extra sodium you need to compete.

  • What should a marathoner eat or drink to consume enough sodium?

  • In marathon training sodium can be consumed in several ways. Sodium is a part of salt (sodium chloride), but it can also be added to foods and drinks. You should lightly salt your meals, especially as training intensifies. In addition, include sodium-rich foods in your daily intake. Ideally, choose salty foods that also provide some nutrition important to runners, such as soups, vegetable juices, frozen vegetables prepared with salty seasonings, packaged rice/pasta mixes, and a variety of salty snacks . Other higher sodium foods include pizza, cheese, pickles, pretzels, and most condiments (catsup, BBQ sauce, mustard). If you’re traveling and have to eat your meals out, you are in sodium-luck since most restaurant foods have a high sodium content.

    In marathon training sodium should also be consumed within sports drinks. Sports drinks are designed to meet multiple needs of the endurance athlete, including replacing sodium and fluids lost in sweat and supplying carbohydrate fuel. So, make it easy on yourself and use sports drinks. As your running schedule intensifies, switch to a sports drink with extra sodium added, such as Gatorade Endurance. The extra sodium encourages thirst, therefore supporting a better hydration plan. (Thirst itself is a poor indicator of hydration, so help encourage your thirst with salt and sodium).

  • Is there a specific amount of sodium to consume daily during marathon training?

  • There are sophisticated ways to measure sodium output in the sweat, but these tests are not available to most of us. So, think about your own body. Are you experiencing early fatigue? This could be a sodium/fluid problem, but it could also be lack of carbohydrates or over-training. Are you getting muscle cramps? Cramps that come on quickly, but can be easily stretched or massaged away are more likely from overuse or fatigue. Cramps that start as a twitch and eventually shut you down may be caused by a lack of sodium. You may be able to avoid total shutdown by quickly taking in salt. An easy way to do this is by adding salt to your sports drink and chugging away. This means you have to carry salt with you. One idea is to save the little salt packets from fast food restaurants and carry them in a plastic bag (along with your gel, mace, and key). Or, ask your training program to set out salt packets at the drink stops along the training route when the mileage/weather calls for it.

    So, is there a particular marathon training sodium amount to consume? No, because each of you is different. Sodium loss on average is 1000 to 3000 mg per hour, but this loss could be much higher in some runners. And you need to consider that you have basic needs for sodium in addition to your loss in sweat. You have to experiment and see how your sodium impacts training. The Institute of Medicine suggests 2300 mg daily for the general population, but this is NOT enough for a marathoner. If you finish your marathon and resume a lighter running schedule in moderate conditions you may be able to take in less sodium than you did during marathon training.

  • Confucius said to think and plan. I’ll edit that to “think and plan for marathon training sodium!”


  • Think before you run. You’re getting better at fueling with carbs, but now you may want to plan for salty carbs.

    Think while you run. You’re hydrating, but maybe you should plan to drink less water and more sports drinks.

    Think after you run. You’ve started including a recovery snack for carb and protein, but now you need to plan to include a salty choice.

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