October 2, 2014

Interview - Sodium Intake in Endurance Sports

Some weeks ago, I had a discussion with my friend and running brother Augusto Gamero about our mutual habits of salt and electrolyte intake while ultra running. This turned into a detailed interview he conducted with Jonathan Toker, inventor of Saltstick caps, that I am happy to relay to you today.


An article by Augusto Gamero

Augusto and I at the Limberlost Challenge Ultra, 2012
Sports nutrition is a very delicate subject. What you eat can be just as personal as your preference for boxers or briefs. And nutritional needs differ from individual to individual. What works for me may not work for you; what works for the elite athlete may not work for the average runner and so on.

Nutrition research has flooded sports magazines and social media over the past few years, spurring the manufacturing of sports nutrition products on the market and making it increasingly difficult to dissociate what we are told “we need” versus our bodies’ actual demands and needs. As I evolved from fun run enthusiast to ultra-marathoner, coaching advice, personal experience, and nutritional information in sports magazines and social media have collectively raised my self-awareness about proper nutrition and its critical role in achieving peak athletic performance. While I am careful with what I put into my body, there is still much to be learned about the interesting, evolving and well debated topic of sports nutrition.

Take salt intake as an example. Up until fairly recently, I was liberally dumping the good stuff on my eggs and enjoyed the satisfactory crunch of the salty snack – chips, pretzles, crackers, you name it! After all, haven’t you earned the right to snack after a grueling morning on the trails? And if you’re simultaneously replenishing low salt levels, aren’t you killing two birds with one stone? The answer to this question is no. Turns out foods like chips only replenish low iodine levels and are poor sources of other necessary salts like magnesium, potassium and electrolytes and athletes need to replenish these as well. I found this out the hard way this past July.

For those of you who have run in the 56k Limberlost Challenge, you know how hot and humid this race can be. After crossing the finish line, I spent almost an hour in the medical tent being treated for severe cramping and although I was in pain, I was happily eating Pretzels. I needed salt – so I was told by the medical team. I knew I had not managed to drink enough fluids and electrolytes. Yet even the pretzels didn’t work their magic and recovery took longer than anticipated.

I also knew that this experience could not be repeated during my next (and bigger) challenge: The TransRockies Run. A 6-day solo run through the Rockies in Colorado, 120 miles with 20,000 ft of elevation gain. Thus, I packed enough electrolytes for 6 days. I used none. Luckily, our race kits included a bottle of saltstick caps. After taking a quick look at its ingredients (very simple, I thought), I decided to give them a try and to take one per hour during the race. Even through brutally hot and dry conditions and demanding terrain, I had no sign of cramping during the 6-day run.

Jonathan Toker, founder of Saltstick caps
Jonathan Toker, the developer of those salt capsules, was also racing at the TransRockies. In fact, he was the overall winner of the 6-day run. Jonathan received a Ph.D. in organic chemistry from The Scripps Research Institute in 2001, worked in the biotech industry for 5 years, and raced in the professional ranks as a triathlete and runner for 5 years. Following a short presentation Jonathan provided on salt intake and SaltStick products, I approached him to ask him a couple of simple questions including his interest to participate in an interview to respond to questions related to salt intake. I reached out to a few people, ranging from experienced runners and triathletes to people that, although not engaged in “extreme” physical activities, pursue an active lifestyle and expressed an interest in the topic.

Q1) When people refer to “salt” intake, does it comprise a mix of different “salts”, such as potassium and magnesium, or is it only limited to sodium chloride (table salt)?

[Jonathan] - That's really two questions. First, in general, when people refer to salt, they are usually talking about sodium chloride (table salt), the most common source of sodium in our diets. However, for athletes, it's critical not to overlook the importance of other crucial electrolytes (salts) that are involved with proper muscle and body function, in particular potassium, magnesium and calcium. The second part of the question is really the difference between sodium chloride and sodium, in terms of target intake measurement, it's important to clarify with your coach or doctor if the suggested amount (usually in mg) refers to elemental sodium or a casual reference to table salt. Table salt is comprised about 40% by weight sodium. All product labels are supposed to indicate elemental sodium content.

Q2) When would you recommend to start taking salt capsules in an endurance event? Is there any correlation with distance, effort, time and level of training?

[Jonathan] - As a general guideline, athletes should consume 200-600 mg sodium each hour during any land-based activity (bike/run) for the duration of the activity. In hot conditions, extreme humidity, or for larger athletes, a higher intake may be appropriate. It is strongly recommended to test your planned electrolyte protocol in training several times before race day. It should be stressed that every athlete sweats differently, reacts to heat and humidity differently, and reacts to the stress of a race or training differently. What this means to the athlete in particular is the importance of testing one's electrolyte replacement strategy in training, prior to race day. Listening to your body prior to and during an event is also key, so you can adapt your electrolyte plan accordingly. Being flexible and keeping your plan simple will give you the best chance of success.

Q3) Is age, weight and sex a factor in the frequency and amount of salt intake in endurance sports?

[Jonathan] - Studies have shown, including PlosOne – Age-Related Decrements in Heat Dissipation during Physical Activity Occur as Early as the Age of 40 that older individuals tend to sweat less and have a more difficult time to release body heat. The general suggestion is to increase fluid consumption and reduce the amount of time spent in hot or sunny conditions. Addition of electrolytes to fluid consumption will ensure that your body is provided with sufficient electrolyte replenishment under those conditions. Decrements in whole-body heat loss capacity were apparent as early as the age of 40 and declined with advancing age. The study concludes that not only should older adults be cautious of the risks associated with performing physical activity when ambient air temperature rises, but middle-aged adults should also be aware that they could be more prone to heat-related illness compared to young individuals.

Women tend to be lighter than men and lose electrolytes as a reduced rate, and so it may be appropriate for women to strive for a lower intake of electrolytes. Similarity, heavier individuals are likely to lose a greater amount of electrolytes. However, as mentioned already, every athlete sweats differently, reacts to heat and humidity differently, and reacts to the stress of a race or training differently, regardless of gender, fitness and age.

Q4) Is there a simple approach to estimate adequate salt intake in an endurance event, based on weight, age and sex?

[Jonathan] - To determine your sweat rate, there are various methods listed online that basically have you measure your weight loss during an activity that will then equal your sweat loss. (For example, Runners World – Know thy sweat rate) Determination of electrolyte loss in sweat requires more scientific testing since the concentration of electrolytes in sweat varies between people. Heavy sweaters tend to find themselves covered in white salt if they wear darker clothing, and the sweat will taste very salty, stinging eyes, etc… Lighter sweaters tend not to notice any salt loss and overall sweat rates tend to be low, keeping clothing dry. . It is strongly recommended to test your planned electrolyte protocol in training several times before race day, such that you will have your loss and intake parameters dialed in experimentally.

Q5) Would you recommend salt intake after engaging in a demanding physical activity such as 2 hours or more of trail running,? If so, why is it important to take salt capsules after a demanding training or race?

[Jonathan] - Maintaining proper hydration and electrolyte balance during hard training or racing can be nearly impossible, and proper post-workout recovery is facilitated by ingesting fluid with electrolytes. This can take the form of a balanced electrolyte supplement along with carbohydrates and protein. A simple strategy to ensure adequate electrolyte replenishment is to take 200-400 mg sodium (1-2 SaltStick Caps) after a hard workout or race. Excess electrolyte ingestion will simply be excreted in the urine.

Q6) Would you recommend salt intake before starting an endurance event?
[Jonathan] - During the days leading up to your event, maintain your weight with adequate hydration with sufficient electrolyte content. The water bottle that follows athletes around to the race expo, etc... should be filled with fluid and electrolytes. This can take the form of a sports drink or water and 1 SaltStick Cap per 1-2 water bottles, either as a capsule or dissolved in water. A word of caution goes to consuming unnecessary and empty calories in the form of sugars. When in doubt, read the nutrition information on the product in question. For races or training over about 4 hours, take 200-400 mg sodium (1-2 SaltStick Caps) the night before your event, and about 200 mg (one capsule) with breakfast before your event. The goal is to start your day with your electrolyte levels at 100% of normal.

Q7) How does a supplement measure compare to eating anything salty during an endurance event?

[Jonathan] - Sodium is sodium, and our bodies don't know the difference as to where it comes from. One challenge of eating salty foods is the strong taste, especially that can accompany the higher levels of sodium necessary for proper replenishment. A more significant consideration is that salty foods usually contain only sodium in significant amounts, meaning that other electrolytes (potassium, magnesium and calcium) will decrease and not be replenished. Using a well-balanced electrolyte source is your best bet for regular intake, and this can be supplemented by foods you enjoy or crave during an event. The longer the event, the more the lack of other electrolytes can interfere with performance.

Q8) Is it a good idea to throw a “salt bomb” in our tummies every hour or so instead of trying to spread the intake evenly through normal food?

[Jonathan] - Based on personal experience and that of other athletes, it is strongly suggested to spread out the intake of electrolytes regularly over time. Especially during racing when our digestive system is already under stress, it is generally not a good idea to consume more than about 400 mg of sodium in one bolus. That being said, it is not necessary to micro-dose salt into our stomachs like an intravenous drip, unless that strategy appears to work for you personally.

Q9) In your knowledge, is there any correlation between gastro-intestinal (GI) issues and salt/electrolyte intake?

[Jonathan] - GI issues can be caused by many issues. Electrolyte intake and balance is one aspect that can either disrupt or soothe a stomach. Personal experience and variability means that your own experimentation is going to be your best guide to success. In an effort to maintain homeostasis, our gut will either facilitate the absorption of water and electrolytes into the bloodstream or prevent absorption, leaving the stomach full. For example, in the case of low blood sodium, excess water in the stomach will likely be prevented from being absorbed as it would further dilute the blood. Excess water in the gut can cause GI distress. In order to resolve such an issue, consumption of a solid electrolyte capsule can be effective at increasing the electrolyte content of the fluid in the stomach without increasing the volume of the fluid, thereby inducing absorption of the fluid and emptying the stomach. A sodium source such as sodium citrate (as found in SaltStick Caps Plus) can further help soothe the stomach. Sodium citrate is the active ingredient formed when drinking Alka-Seltzer.

Q10) A recent (2014) article published in irunfar summarizes the results of research presented at the Medicine & Science in Ultra-Endurance Sports Conference earlier this year. One of the topics discussed at the conference and presented by the director of research at Western States Endurance Run, Dr. Marty Hoffman, called Sodium Supplementation, Drinking Strategies, and Weight concluded that if you are “craving salt, eat something salty” . The article further raises the issue of whether ultrarunners need to take salt tabs during a 100-mile race and to which it notes that “the short answer is no” and that, according to a study by Winger (2013), “sodium supplementation during an ultra has no significant effect on the blood level of sodium at the end of the race”. In your opinion, are there other factors that need to be considered in reading and supporting such conclusions?

[Jonathan] - One of the reasons that electrolyte studies remain so controversial and the matter of electrolyte supplementation still open to study is that studies have shown both an effect and no effect on various populations, depending on the study conditions and parameters. Blood (plasma) levels represent but one marker of sodium content in the body. It is so far not easy to determine the sodium content within the cells, which as any biologist will tell you, is where sodium exchange occurs (along with potassium). As such, it's quite likely that plasma sodium levels can be maintained at the expense of cellular sodium content. The body, by definition, has a limited sodium content. Analysis of the elemental content of the human body lists sodium at about 90g (per 70kg body weight), much of which is bound and unavailable. As such, it's pretty easy to see mathematically that loss of sodium by sweating over time, will have a dramatic impact on the sodium content in the body.

Another consideration is the difference between survival and performance: while you may survive without sodium supplementation, are you likely to perform your best?

As well, many of these researchers state something like “craving salt, eat something salty” while dismissing salt tablets or capsules. This is an inconsistent message. Bottom line is that athletes have found that consumption of electrolytes in some form, along with energy (calories) and water are fundamental to their success.

Q11) Is there any robust science around the significance of proper salt intake in endurance sports? And, could you provide readers with useful resources on the topic?


· Quantitative article about sodium and fluid intake and loss over time, and how the concentration of electrolytes can increase and decrease depending on fluid intake. It's simple math how people can drink too much to dilute plasma sodium, but equally easy to become dehydrated over time with reduced fluid intake. An apparent happy medium lies somewhere between. The article can be found here: http://www.slowtwitch.com/Training/General_Physiology/The_Math_of_salt_loss_1093.html

· J Athl Train. 2009 Mar-Apr; 44(2): 117–123. Sodium Replacement and Plasma Sodium Drop During Exercise in the Heat When Fluid Intake Matches Fluid Loss. Costas A Anastasiou, Stavros A Kavouras, Giannis Arnaoutis, Aristea Gioxari, Maria Kollia, Efthimia Botoula, and Labros S Sidossis, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2657026/

"Conclusions: The data suggest that sodium intake during prolonged exercise in the heat plays a significant role in preventing sodium losses that may lead to hyponatremia when fluid intake matches sweat losses."

· Sports Med. 2001;31(10):701-15. Fluid and electrolyte balance in ultra-endurance sport. Rehrer NJ.

· ASCM Guidelines "http://www.acsm.org/docs/publications/Roundtable%20on%20Hydration%20and%20Physical%20Activity.pdf "

· Exercise-Associated Hyponatremia http://cjasn.asnjournals.org/content/2/1/151.full

· Exercise associated hyponatraemia: quantitative analysis to understand the aetiology http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2492017/

My confession: I still love chips!

Happy Trails!


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