Thinking of Joining USA Triathlon?

Be a part of our 550,000 member community of multisport athletes. Membership benefits include a subscription to the quarterly USA Triathlon magazine, discounts from USA Triathlon partners, inclusion in the national rankings, excess accident insurance at events, and savings at races. To see why you should join or renew today, visit the membership benefits page. Already a member? Login below.

Forgot Password  |  Forgot Member ID  |  Help Renew Membership Become a Member

Electrolytes and Ironman Triathletes

By Bob Seebohar

electrolytesElectrolyte consumption for Ironman athletes has been a very popular topic, especially as of late. No matter what school of thought you subscribe to, there is one thing for sure: many Ironman athletes make some mistakes that can have a negative impact on race day. However, these may be easily avoided with a bit of background knowledge.

Dietary Sodium

We all know that the average Western diet is high in sodium. Endurance athletes are known to go to extremes of adding copious amounts of salt to their foods throughout the day to try to keep up with the amount they lose. However, if the diet contains a high amount of sodium, the body requires more sodium on a daily basis to remain in balance. As the amount of sodium increases in the diet, the amount lost in sweat also increases to maintain homeostasis. The body eventually becomes familiar with this high amount of sodium and requires it day in and day out thus driving the daily need for more sodium. The end result is that you need more daily sodium to keep your body functioning properly both in and out of training.

However, if less sodium is consumed in the daily diet, it is much easier for the body to remain in balance. Sodium is still lost through sweat during training but it is easier to maintain these levels by implementing sodium supplementation strategies immediately before and during training and competition. The ideal scenario is to follow a lower sodium daily nutrition plan and implement a competition electrolyte protocol. After competition is finished, return to your lower sodium nutrition plan once again.

The Electrolytes 

The five main electrolytes that are often discussed when it comes to athletic performance are sodium, chloride, potassium, calcium and magnesium. While sodium, an extracellular compound, gets much of the attention since it is probably the most important electrolyte, the other four electrolytes should not be overlooked as they all function to support physiological training adaptations and physical performance. Here is a little information about each electrolyte:

  • Both sodium and potassium are important in nerve conduction which helps generate the signals from the central nervous system to the muscles to perform work. Potassium, found inside of cells, also works closely with sodium and chloride in maintaining the body’s fluid balance.
  • Chloride binds to both sodium and potassium and contributes to muscle functioning. Chloride is always found in combination with sodium and potassium. 
  • Calcium is the mineral that is mostly associated with bone health. However, what not all athletes realize is that calcium also assists with muscular contraction, the metabolism of glycogen, neuromuscular conduction and messaging between cells.
  • Magnesium is usually overlooked in the electrolyte supplementation program of Ironman athletes when in fact it can be responsible for poor performances because it is important in the generation of ATP, muscle contraction and the transmission of nerve impulses.

As can be seen, the role of electrolytes spans far greater than simply maintaining fluid balance or trying to prevent the “mystery” cramps that Ironman athletes often experience. There are many other physiological functions that these electrolytes contribute to and all work in concert with one another to support intense physical exercise. Having a combination of all five electrolytes is crucial for proper physiological functioning and adaptations to training.

Sodium Loading

There has been some research to suggest that acute sodium loading the night before or morning of a race can be beneficial in promoting good fluid balance and acclimating to warmer environments. Chronic sodium loading (greater than 2 days), common among many endurance athletes, can sometimes produce bloating and weight gain the week leading up to a competition. However, acute sodium loading has been shown to have minimal adverse effects with maximal performance benefits. Combining acute sodium loading with low sodium diet can work to improve performance while minimizing any adverse effects. For more information about acute sodium loading, refer my e-book, “Sodium Loading for Endurance Athletes”, available at


Wrapping up this information in summary format, we are left with the following take-home messages:

  1. Follow a lower sodium diet in your daily nutrition to improve health and reduce the amount of supplemental sodium needed during training and racing.
  2. All five electrolytes are important in concert with one another due to their role in muscle functioning, fluid balance and the formation of ATP.
  3. Acute sodium loading may prove as a successful means for improving hydration status for Ironman racing.

These small steps will provide huge dividends for any Ironman athlete but they should be implemented far in advance of the competition date. Get your daily sodium balance in check to lower amounts then try an acute sodium loading protocol at least two or three times in quality training sessions before competition day and enjoy the success of a better race day!

seebohar book coverBob Seebohar, MS, RD, CSSD, CSCS is a Sport Dietitian, USAT Level III Elite Coach, USAT Youth and Junior Coach and an exercise physiologist. He was on the coaching team of Susan Williams, 2004 Olympic Triathlon bronze medalist, and was the head coach of Sarah Haskins, 2008 Olympic triathlete, and Jasmine Oeinck, 2009 Elite National Champion. Bob was previously a sport dietitian for the U.S. Olympic Committee and the 2008 Olympic triathlon team. Bob has worked with hundreds of age-group triathletes and professionals to help them lose weight and body fat while optimizing performance through nutrition periodization and metabolic efficiency. Bob recently published a Metabolic Efficiency Recipe book with over 100 recipes that provides athletes even more options to follow metabolic efficiency training. Visit for more information.


The views expressed in this article are the opinion of the author and not necessarily the practices of USA Triathlon. Before starting any new diet or exercise program, you should check with your physician and/or coach.