Last Updated on January 27, 2022 by Heather Hart, ACSM EP, CSCS
Let me be blunt: this probably isn’t the ultramarathon electrolyte supplementation post you are expecting to read. In fact, if I’m being honest, it’s not even the post I expected to write.
Last week I sat down to write what I assumed would be a simple post about the electrolyte needs of ultramarathon runners. Essentially a “Heather” version of the exact same advice that is regurgitated endlessly across the internet among running websites and blogs. Instead I found myself immersed in ever evolving and fascinating research, combined with a bit of controversy, that made me really rethink the roles of electrolytes and the need for supplementation – specifically of sodium -in ultramarathon running.
I will preface this post with the fact that I’ll be presenting a ton of research with very conflicting evidence and conclusions. NONE of this is to be considered a recommendation by me, to you, when it comes to your hydration and electrolyte supplementation protocol during an ultramarathon. I am also not insinuating that I agree nor disagree with the research presented, or that I believe some runners are doing things “wrong”.
Rather, I wrote this post because:
- I think this emerging research is fascinating, and think many of you may as well. Science is always evolving. That’s the point, we’re constantly trying to prove or disprove if the things we believe to be true, are, in fact, true. Advice that may have once been solid, in time may be disproven. Or, it may turn out to stand the test of time. But I, for one, think it’s pretty cool to see scientist constantly questioning…especially when it comes to ultramarathons, a sport I happen to really enjoy.
- It’s a reminder that we cannot blindly take nutrition and supplement advice. Just because other runners do it, a blogger (like me) gives advice, or a company makes specific claims, doesn’t necessarily mean that practice is correct, the advice is sound, or those claims are true.
Alright, buckle up…this one is lengthy, but in order to truly understand the issues at hand, it needs to be.
Electrolytes & Their Role in Ultramarathon Running
Before we get into the details of electrolyte supplementation during an ultramarathon, and the current research questioning it’s effectiveness, let’s have a quick refresher on what electrolytes are in the first place. If you already completely understand this topic, feel free to skip on ahead to the section: Ultramarathon Electrolyte Supplementation (or, click here).
Note: If you are looking for an in-depth explanation specifically of electrolytes, I encourage you to start by reading the post “Salt Tablets for Runners? Electrolyte Needs & Supplementation Explained“, then returning to this post.
What are electrolytes & why do we need them?
Electrolytes are minerals we obtain through food and drink, that are essential for our bodies to function properly. They are responsible for everything from helping maintain appropriate hydration/fluid levels within our body, to muscle and nervous system function, to helping maintain a healthy pH level within our body, and more.
Electrolytes are found within the extracellular (outside of your body’s cells) and intracellular (inside of your body’s cells) fluids. Common fluids to keep in mind in the instance of discussing running are blood, urine, and sweat. Subsequently, electrolytes are excreted from our bodies through blood, urine, and sweat loss (as well as fecal matter, vomit, diarrhea, etc.).
Sweat Rates & Electrolyte Concentration:
When we exercise, we sweat. It’s our bodies natural cooling system to counter the heat created by all of the bodily functions needed to exercise (muscle function, metabolizing fuel, etc.) Our body pushes water out of sweat glands, located all over your body, to the outer layer of your skin. As the water in the sweat evaporates, the surface of the skin cools, which helps lower your body temperature.
During exercise, sweating is the main cause for electrolyte loss, especially of sodium and chloride. According to the American College of Sports Medicine, on average people lose between 0.8 to 1.4 liters (roughly 27.4 to 47.3 oz.) of sweat, or 2 to 6 percent of their body weight during exercise. (1)
The amount of electrolytes lost in your sweat varies as well. But on average, runners lose about 800mg of sodium, 195 mg of potassium, 20 mg of calcium, and 10 mg of magnesium per hour of running in their sweat. (1)
But, it’s important to remember that:
- Sweat rates (volume of sweat lost per hour) vary greatly from person to person.
- The composition of sweat/concentration of electrolytes in sweat vary greatly from person to person (as an example, research has found that the sodium concentration in sweat can vary among individuals from 200 to 2,000 mg/L )
- Sweat rate can vary within a single individual based on factors such as temperature, humidity, altitude, intensity of exercise, hydration status, and even current fitness level.
Electrolyte imbalances within our bodies can cause a number of negative physical side effects that range from unpleasant to downright dangerous, depending on the severity of the imbalance. Side effects can include (but aren’t limited to) things like: dizziness, headaches, muscle weakness and cramping, all the way to vomiting, seizures, loss of consciousness, and even death.
Most people are familiar with the concept of dehydration. This occurs when inadequate amounts of water are consumed to compensate for fluids lost through normal bodily functions (urine, sweat, etc.) It can result in a condition known as hypernatremia, or when the sodium level in the blood becomes abnormally high because water loss exceeds sodium loss.
But, equally as important is hyponatremia. Hyponatremia is a condition in which sodium (salt) levels in the blood become abnormally low. In the case of running, this can often happen because over overhydration, when a runner consumed too much water. While hypernatremia can be dangerous, hyponatremia has the potential to be deadly.
Exercise-associated hyponatremia (EAH…you’ll see use this acronym a bunch in this post) is one of the most common medical complications in long-distance training and racing, and has been recognized as a cause of race-related death and life-threatening illness among marathon runners. It’s rare, but it does happen.
Studies show that that reported incidences of EAH are between of 5-51% (and in one study, upwards of 65% ) following endurance events where athletes are screened, with marathon runners, ultramarathon runners, Ironman athletes, long-distance backpackers, and military service members most commonly affected (3).
However, studies also show that only 0.1% to 1.0% of endurance athletes experience symptomatic EAH (3) . Meaning: PLENTY of athletes are finishing races in some state of hyponatremia. Experts tend to agree that some level of hyponatremia or hypernatremia are to be expected during physical activity, especially over the course of an ultramarathon distance.
What’s important to remember is this: according to numerous sources, there is not a single report in the medical literature of dehydration being a proven, direct cause of death in a marathon runner. On the other hand, we are aware that there are at least a dozen recorded deaths during endurance events caused by exercise-associated hyponatremia. So while the majority of EAH cases are harmless, there is always possibility of these cases worsening and leading to a detrimental outcome.
Electrolytes and Ultramarathons: A Controversial Science?
Now, I’ve probably spent endless paragraphs reiterating the dangers of hyponatremia to a crowd of ultrarunners reading this post who already know these risks. After all…that’s why we take electrolytes in the first place, isn’t it? To make up for the electrolytes lost in sweat, so that we can rehydrate while running without risking hyponatremia, right?
In theory, yes.
There is endless supported, documented research telling us that that electrolyte supplementation during exercise is necessary as a part of the rehydration process. On top of that, we’ve routinely been told, both by experts in the field and a barrage of marketing from supplement and sports drink companies, that electrolyte supplementation can help us avoid a whole slew of other “not really what I was hoping for on race day” issues, such as cramping and gastrointestinal distress, as well as help us with performance.
And that belief is common. Researchers from the Western States Run Research Committee found that 90%–96% of runners at the 2011, 2013, & 2014 WSER used sodium supplements (14). Electrolyte supplementation, with a heavy focus on replacing sodium, is a well known and frequently practiced strategy among runners.
But are these claims true?
Electrolyte Supplementation: Does it Work in Ultramarathon Distances?
Now for the fascinating (again, at least to me) part. I have spent the better part of last week with somewhere, on average, of 50+ tabs open on my internet browser, of ENDLESS research on this topic. I kept digging and digging, because frankly, I was shocked to read what I was reading. And what I was reading can be summed up by a statement from Martin Hoffman, MD, FACSM, founder of Ultra-Endurance Sports Science & Medicine, and former Research Director of the Western States Endurance Run (among a bunch of other accolades):
“Ultramarathon runners continue to have misunderstandings about the need for sodium supplementation during ultramarathons. Few ultramarathon runners recognize that supplementing sodium intake beyond that in food and drink is generally not necessary during ultramarathons or that it could result in overhydration. Continued educational efforts are warranted to help ensure safe participation in the sport.” (15)
A little surprised? Me too. Let’s dive a little further into some more of the research I found.
As mentioned, your sweat contains various levels of all electrolytes. However, sodium(Na+) is found in greatest concentrations in sweat, is the major ion of the extracellular fluid, helps regulate fluid balance, and contributes to the generation of action potentials for muscle contraction, and is the main electrolyte referenced when talking about athletic performance. Therefore in the electrolyte research I’m sharing, the studies are focusing on sodium blood levels.
Sodium Supplementation to Prevent Hyponatremia?
Many runners believe that the main reason for taking sodium supplements is to help prevent the onset of EAH.
According to the authors of a recently published (November 2021) paper in the Clinical Journal of Sport Medicine, titled “Effect of Sodium Supplements and Climate on Dysnatremia During Ultramarathon Running“, sodium supplementation does not prevent Exercise-associated Hyponatremia, nor does sodium supplementation cause hypernatremia.
Their research took place during the 50 mile stage of the 2017 six day RacingThePlanet’s 4 Desert Ultramarathon. In this study, researchers collected post race blood sodium data from 174 runners. Out of the 174 participants, eleven (6.3%) runners developed EAH, and 30 (17.2%) developed hypernatremia. (18)
And here’s what they found: neither rate nor total ingested supplemental sodium was correlated with either EAH or hypernatremia, and further, there were no significant differences in drinking behaviors, or electrolyte supplement use compared to the runners in the study who did NOT develop EAH or dehydration. (18)
But they are not the first researchers to come to these conclusions. There are countless other studies available. Here’s two more examples:
2014 Western States Endurance Run
A study during the 2014 Western States 100 Miler analyzed postrace blood samples of 181 finishers, and compared it to self reported mid race electrolyte supplementation data. From those samples, researchers found that 6.6% runners were hyponatremic, 7.2% were hypernatremic, and 86.2% were within “normal” values. (12)
- Sodium supplementation was practiced by over 90% of runners in this study
- Hyponatremic finishers did not drink more water vs. electrolyte drinks compared to those with normal serum ranges.
- Hyponatremic finishers did not use sodium supplements less, nor were they less likely to drink to thirst, compared to those with normal serum ranges. (12)
Researchers from this study concluded: “the use of sodium supplements is not necessary to avoid hyponatremia during continuous exercise in moderately hot conditions for up to 30 h. Avoiding overhydration seems to be the most important means for preventing hyponatremia under these conditions.” (12)
Cape Town Ironman triathlon
In a research study of the 2001 Cape Town Ironman triathlon, 53 triathletes in a research group at the were given electrolyte tablets, each containing 620 mg table salt (244 mg Na+ and 376 mg Cl−). And 61 triathletes in the control group were given placebo tablets. Both groups were asked to take 1–4 tablets every hour, and were discouraged from taking any other electrolyte‐containing tablets during the race.
The results? There was no significant difference in serum sodium concentrations, finishing time, subjective measures of exercise intensity and mental wellbeing, nor in the prevalence of hyponatremia or hypernatremia after the race between the groups who did take electrolyte supplements and the group who did not. (8)
Sodium Supplementation for Ultramarathon performance?
In another paper based on data from the Lipman/Running4ThePlanet study, researchers also assessed the effect of sodium supplementation as a predictor of race performance in ultramarathon runners. No association was found between sodium supplement intake and ultramarathon performance, even when comparing weight-adjusted rate and total sodium consumption.
In fact, dehydrated runners were found to have the best performance, with significantly faster pace and finishing times. The authors state: “This reinforces the message to avoid overhydration and not to aggressively pursue electrolyte supplements to impact running performance.” (19)
Electrolyte Supplementation for Cramping or Nausea?
Another study out of the Western States Endurance Run research committee analyzed the dietary intake of 20 race finishers of the 2014 WER race, as well as post race blood serum samples. Of those 20 finishers:
- 10 % were hyponatremic
- 39 % reported muscle cramping or near cramping
- 57 % reported having symptoms of nausea or vomiting
There was no significant difference in sodium intake between those who experienced these issues compared to those who did not experience these issues. Researchers concluded that exercise-associated muscle cramping, dehydration, hyponatremia, and nausea or vomiting during exercise up to 30 hours in hot environments are unrelated to total sodium intake rate or volume, despite a common belief among ultramarathon runners that sodium is important for the prevention of these problems .(10,14)
What DOES Work?
If sodium supplementation doesn’t work to prevent EAH, cramps, or nausea, what does?
It turns out, in multiple research studies, scientist came to similar conclusions:
- In Lipman’s RacingThePlanet’s research, the study found those with EAH were 14 kg heavier at the start of the race, had logged significantly less training distances, and averaged 5 to 6 hours longer to cover 50 miles (80 km) than the other participants. (18)
- During a 2009 WSER study, researches found that EAH was unrelated to age, sex, finish time, or use of nonsteroidal anti-inflammatory drugs during the run, but those with EAH had completed a smaller number of 161-km ultramarathons. (13)
- A study of runners during a 100 mile ultramarathon found that gastrointestinal distress was experienced by half of the participants, but was unrelated to food or fluid intake. Researchers found that runners with GI distress tended to complete fewer training miles and to do shorter training runs. (7)
Is this because appropriate training has a physiological effect that helps runners prevent these electrolyte imbalances? Or is it simply because runners with more training and race experience are more in tune with the needs of their bodies, therefore avoiding overhydrating, as well as having fine-tuned nutritional strategies to avoid cramping or GI issues? Researchers don’t say specifically…but the coach in me is going to emphasize that the takeaway message here is: training MATTERS.
So… Electrolytes or No Electrolytes? WHAT DOES THIS ALL MEAN?
It’s important to note that there are many possible flaws in the above studies. A number of the observational studies relied on runner surveys / questionnaires to detail their supplement consumption, both in dosing and frequency, during the course of a 100 mile race.
I don’t know about you, but I can barely remember how to tie my shoes at the end of a 100 miler, never mind recall exactly how many Endurolytes I had, or when I took them.
There’s the fact that many of the studies cited have been performed at ultramarathons with notoriously warm weather, which certainly may have contributed to runner’s hydration strategies (or overhydration status), or even the body’s response to the temperature.
We can continue to criticize many points of these studies, including sample sizes, methods, whether or not the findings were statistically significant, etc.
Yes, Electrolytes Still Matter
It goes without saying that our bodies need electrolytes, and at some point, we’ll need to replenish what we lost.
Let me say it one more time, ELECTROLYTES DO MATTER, and I don’t believe that anyone in the health, sports, or fitness industry disagrees.
The argument here is whether or not electrolyte supplementation, specifically sodium, does what we as runners have been led to believe it does (prevention of EAH, cramps, nausea, etc), during our workouts or races.
Electrolytes Other Than Sodium:
We’ve talked endlessly about sodium supplementation, but as you either already know, or may have seen from my other post on running and electrolytes: there are electrolytes other than sodium in most supplements.
Even table salt contains sodium and chloride.
So making a bold statement such as “electrolyte supplements don’t work”, by using studies solely focusing on sodium, we are excluding the potential benefits and needs of these other important minerals.
Endless Anecdotal Evidence Exists.
Further, endless anecdotal evidence exists from ultramarathon runners everywhere when it comes to their personal experiences with running and electrolyte supplementation. From being absolutely sure that sodium supplementation helps them prevent cramps, to noting that electrolytes help prevent stomach issues during and after long runs, to simply feeling better after a race or run. These runners have integrated electrolyte supplementation into their regular hydration and nutrition strategies with no known adverse reactions.
However, Electrolyte Misconceptions Still Exist.
Leaving all of the contradicting research aside, many runners still don’t know exactly why they take electrolytes, they’ve just heard that they should. Personally, I informally polled my Instagram followers, asking them why they take electrolyte supplements while running, and at least 50% of the results included some sort of ambivalence or question, insinuating they weren’t really sure why they take electrolytes.
Addressing Overhydration in Ultramarathon
Despite the ongoing debate about whether or not ultrarunners need to take electrolytes, all experts agree that there needs to be more education and understanding among the ultramarathon community about the risks of overhydration. Understanding why it may happen might is a great first step.
One of the major contributing factor to sweat rates (volume of sweat lost per hour) is overall exercise intensity. The higher the intensity, the harder your body needs to work to keep itself cool, thus, more sweat.
Now, please don’t get me wrong: ultramarathons are in no way easy. However, the overall intensity during an ultramarathon is generally far less than that of say, a half or full marathon. Especially when we consider the majority of runners who may actually be walking for the latter stages of a longer ultra.
But, runners may continue hydrating at a constant rate, even when intensity begins to decrease and sweat rate drops, resulting in overhydration.
Greater access to water:
It’s not uncommon to see ultrarunners carrying their own hydration, and plenty of it. Hydration packs are a common sight at ultramarathons, and can carry on average, anywhere from 1.5-2L of water. This gives runners constant access to water, and may lead to overhydration.
False sense of security with supplements?
It’s been demonstrated over and over that runners, particularly ultrarunners, believe that electrolytes are beneficial for preventing hyponatremia (and again, whether they actually are or not is clearly still highly debated).
In 2018 researchers polled 1,152 ultramarathon runners, asking whether sodium supplements should be made available at ultramarathons
- Two-thirds (66.4%) of study participants indicated that sodium supplements should be made available at ultramarathons
- Of these respondents, 65.5% believed sodium supplements would prevent EAH
- 59.1% believed sodium supplements would prevent muscle cramping
- Of those indicating that sodium supplements should not be made available:
- 85.0% indicated it is because runners can provide their own
- 27.9% indicated it is because they are not necessary
- 12.1% indicated they could increase thirst drive and cause overhydration.
(Source: Ultrarunners Longitudinal TRAcking (15)
If such a large majority of runners agree that sodium supplementation protects them from the risks of overhydration, then it’s very possible that runners aren’t remaining actively aware of the fact that they may be drinking too much (assuming “too much” can’t happen.)
Mistaking Hyponatremia Symptoms for Hypernatremia:
Here’s a real kicker: some symptoms of hypernatremia and hyponatremia symptoms are identical. Some of those symptoms include:
- Muscle weakness
- Nausea and vomiting
In these cases, runners may mistakenly assume these symptoms are due to dehydration, and continue to overhydrate in attempts to correct the issues. This of course will only contribute to the EAH worsening.
Relying on Weight Loss as an Indicator
Countless research and literature suggests that a change in body weight, due to sweat loss, greater than 2% should be avoided. ACSM states in their position stand on Nutrition and Athletic Performance:
“Fluid deficits of >2% body weight can compromise cognitive function and aerobic exercise performances, particularly in hot weather.” and “Ideally, athletes should drink sufficient fluids during exercise to replace sweat losses such that the total body fluid deficit is limited to <2% BW.” (21)
However, much of the research in ultramarathon running contradicts that. In fact, a common theme in these papers seems to be the understanding that in longer ultramarathons, such as a 100 miler, weight loss up to 3%–4% due to water release bound to glycogen (i.e., using your glycogen stores for energy) is to be expected, and is not an indicator of hydration status.
Further, the majority of the front of the pack runners and the race winners? They tend to more often than not, finish at lower weights than they started.
In a guest article for Ultrarunning Magazine, Dr. Hoffman writes: “Contrary to conventional wisdom, there is no evidence that weight loss of a few percent impairs performance in ultramarathons considering the baseline weight is in the hydrated and carbohydrate-loaded condition. In fact, we’ve seen a direct relationship between running speed and percent body weight loss in our recent studies at 100-mile races. In other words, there is a trend for the faster runners to lose more weight than slower runners. Some of the fastest runners have lost five – seven percent of their starting body weight by the time they reach the finish line, feeling fine and without medical problems.” (9)
Body weight and EAH:
Research points out that further problems with automatically associating weight loss with the need to rehydrate, is that as it turns out, many people with exercise associated hyponatremia actually LOSE weight, and not gain it, like we suspect.
In a 2021 paper titled “Incidence of exercise-associated hyponatremia during a high-altitude 161-km ultramarathon” authors discuss an observational study conducted on the participants of the Leadville Trail 100 run. Post race blood serum samples analyzing sodium levels of 84 finishers showed that twenty percent had Exercise-associated Hyponatremia. The runners with EAH lost the least body weight (-0.33 kg) compared with runners who did not develop EAH (-1.56 kg). (16)
The authors state: “although this difference was not statistically significant (p=0.08), his trend towards maintaining body weight (rather than losing weight during a 161-km run) suggests that overdrinking with or without fluid retention was likely to contribute towards EAH while also highlighting the difficulties of using body weight as an accurate surrogate measure of natremia in longer races.” (16)
In these instances, assuming the loss in body weight is due to an excessive loss in overall water volume, could cause a runner to unnecessarily attempt to rehydrate with more water, only furthering the development of EAH.
Your Ultramarathon electrolyte supplementation strategy:
So, if you’ve come to the post (and actually stuck with it to this point) looking for suggestions on your specific race day electrolyte strategy…I’m sorry to say I don’t have an exact one for you.
Because sweat rates and electrolyte sweat concentration are so individual, combined with the fact that runners needs will vary from race to race based on things like environmental factors and intensity…there is no “one size fits all” strategy.
But, for the sake of giving you SOMETHING, when discussing sodium in particular, here are some current recommendations from various nutrition and medical organizations:
ISSN Position Stand:
According to the 2019 International Society of Sports Nutrition (ISSN) Position Stand: nutritional considerations for single-stage ultra-marathon training and racing
- Runners should consume sodium in concentrations of 500–700 mg·L− 1 of fluid (also ACSM’s position stand on exercise and fluid replacement )
- Slightly greater amounts of sodium (and other electrolytes) will be required in hot (e.g., > 25 °C / 77 °F) and/or humid (e.g., > 60%) conditions when sweat rates are elevated
- in such conditions, runners should target ~ 300–600 mg·h− 1 of sodium (1000–2000 mg of NaCl).
ISSN continues: “The amounts taken should also be offset against the sodium consumed from salt-containing foods, although it should be noted that it is unlikely that the recommended rate of sodium intake will be achieved from foods alone. In addition, the concentrations of some electrolytes (e.g., sodium) in many commercially-available electrolyte replacement products are insufficient to meet the recommended intakes. As such, runners are encouraged to pay close attention to the ingestion method and composition of their electrolyte formula.”
Further, ISSN states that there is anecdotal evidence that effervescent (dissolvable) electrolyte tablets, and liquid electrolytes added to water, can compromise drink palatability during ultramarathons, resulting in runners drinking less. As such, ISSN recommends capsules or tablets that can be swallowed whole. (22)
The World Athletics (formerly IAAF) Consensus Statement on Nutrition for Athletes
In the 2019 International Association of Athletics Federations Consensus Statement: Nutrition for Athletics, the IAAF takes a much more ambiguous suggestions stating:
“The best advice to enable adequate replacement of sweat losses has been debated, as have the benefits/impairment to performance associated with proactive or passive hydration strategies. What is irrefutable is that the fluid needs of most Athletes are determined by their reliance on the evaporation of sweat to dissipate the heat produced during exercise or absorbed from a hot environment. Athletics, probably more than any sport, illustrates the futility of trying to apply a single set of guidelines for behavior regarding fluid and electrolyte replacement around sport.”
More specifically, IAAF adds:
- In the case of Athletes who undertake distance and ultradistance events at slower paces with lower sweat rates, specific advice against overconsuming fluids may be necessary to avoid the problems associated with hyponatremia (low blood sodium levels, usually due to excessive fluid intake)
- In some scenarios where large sweat-associated electrolyte losses occur, replacement of electrolytes, particularly sodium, may be beneficial in within and post exercise plans; this may be achieved via the use of whole foods or sports food/supplement choices. (4)
Food vs. Supplements
The International Journal of Sport Nutrition and Exercise Metabolism titled “Nutrition for Ultramarathon Running: Trail, Track, and Road” suggests that your race day fueling strategy should be enough to replenish lost electrolytes.
“In conjunction with hydration strategies, sodium supplementation, before and during running, is a common practice among ultramarathon runners, owing to beliefs that sodium will prevent dehydration, muscle cramping, nausea, and EAH, and subsequently enhance performance. It has, however, been demonstrated that supplemental sodium is not necessary to maintain euhydration (normal hydration status) during ultramarathon competition, even under hot ambient conditions. Moreover, sodium intake during exercise will also not prevent EAH in the presence of hyperhydration. Thus, best practice suggests avoiding attempts to replace all sodium lost in sweat through the intake of sodium supplementation during ultramarathon running, recognizing that considerable sodium is present in the typical race diet (e.g., electrolyte beverages, sports bars and gels, savory sandwiches, crisps, pretzels, and soups).” (6)
Feeling confused? I get it. Me too.
As mentioned earlier, the cool thing about science is that we’re constantly trying to prove or disprove if the things we believe to be true, are, in fact, true. Advice that may have once been solid, in time may be disproven. That shouldn’t necessarily come as a surprise.
Further, while I won’t dive deep into the subject, I feel I can’t leave out the powerful influence that huge corporations and their brand marketing have on the beliefs and practices of so many consumers.
What was most shocking to me wasn’t necessarily the findings, but the fact that some of this research is nearly a decade old, and so many runners haven’t heard of it. I had heard bits and pieces in the past, but personally wasn’t aware of the extent of the research available pointing to the idea that perhaps, sodium supplementation during a race really does not work.
A friend of mine in the industry said it best:
“I also am not surprised that you or I haven’t heard much of this before. It would not make sense for major sports outlets to report on studies that would lead to doubt of supplement efficacy when major sponsors and contributors include sports nutrition companies and athletes sponsored by sports nutrition companies. Not to say this should make us believe these studies outright, but of course if something groundbreaking were to come out, these companies would try to quiet that storm.”
If you’re feeling a bit blindsided but also fascinated by this topic, I definitely encourage you to read the following articles regarding the potentially questionable research by The Gatorade Sports Science Institute, their affiliation with the American College of Sports Medicine, and the influence and marketing of the sports drink/supplement industry:
The Controversial Science of Sports Drinks (The Atlantic)
You Don’t Need Sports Drinks To Stay Hydrated (FiveThirtyEight)
I certainly am not insinuating that I agree nor disagree with any of it. However, when you consider that in 2020, the global sports drink market was valued at $26.24 billion (USD), and more specifically, the global electrolyte mixes market was valued at $3.47 billion (USD), this whole topic definitely gives room for pause.
So, let’s wrap up this electrolyte rabbit hole I’ve gone down (and dragged you along with me), and summarize the past 5,000 words with the following important key points:
- Individual sweat rates, electrolyte concentrations lost in sweat, and replacement needs while running vary greatly.
- Supplementation aside, making sure your daily diet is full of necessary electrolytes to help replenish your body is key.
- The debate as to whether or not electrolyte, specifically sodium, supplementation does what most ultrarunners think it does, continues to rage on.
- Supplements aside, experts agree that avoiding overhydrating is the best strategy for preventing exercise associated hyponatremia. Be aware of your rehydration rate, and try to not consume a volume of fluid that is GREATER than what you’ve lost.
- Research shows that proper training can help runners avoid cramps and gastrointestinal distress during an ultramarathon. So, put in the work!
- The BEST re-hydration and electrolyte replacement strategy is the one that works for YOU. Learn your sweat rates during a variety of temperatures and environments. Find a strategy that works for you.
- Listen to your body for signs of hyponatremia. Remember that they can be identical to that of hypernatremia, but may also include things like swollen fingers or a sloshy stomach.
- If you have any questions at all about YOUR specific hydration and electrolyte needs, consult a medical or nutrition expert.
For more on this topic, again, please refer to the post: Salt Tablets for Runners? Electrolyte Needs & Supplementation in Running Explained
- American College of Sports Medicine, Sawka, M. N., Burke, L. M., Eichner, E. R., Maughan, R. J., Montain, S. J., & Stachenfeld, N. S. (2007). American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and science in sports and exercise, 39(2), 377–390. https://doi.org/10.1249/mss.0b013e31802ca597
- Baker, L. B., Barnes, K. A., Anderson, M. L., Passe, D. H., & Stofan, J. R. (2016). Normative data for regional sweat sodium concentration and whole-body sweating rate in athletes. Journal of sports sciences, 34(4), 358–368. https://doi.org/10.1080/02640414.2015.1055291
- Buck E, Miles R, Schroeder JD. Exercise-Associated Hyponatremia. [Updated 2021 Sep 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK572128/
- Burke, L. M., Castell, L. M., Casa, D. J., Close, G. L., Costa, R. J. S., Desbrow, B., Halson, S. L., Lis, D. M., Melin, A. K., Peeling, P., Saunders, P. U., Slater, G. J., Sygo, J., Witard, O. C., Bermon, S., & Stellingwerff, T. (2019). International Association of Athletics Federations Consensus Statement 2019: Nutrition for Athletics, International Journal of Sport Nutrition and Exercise Metabolism, 29(2), 73-84.
- Cairns, R. S., & Hew-Butler, T. (2015). Incidence of Exercise-Associated Hyponatremia and Its Association With Nonosmotic Stimuli of Arginine Vasopressin in the GNW100s Ultra-endurance Marathon. Clinical journal of sport medicine : official journal of the Canadian Academy of Sport Medicine, 25(4), 347–354. https://doi.org/10.1097/JSM.0000000000000144
- Costa, R. J., Knechtle, B., Tarnopolsky, M., & Hoffman, M. D. (2019). Nutrition for Ultramarathon Running: Trail, Track, and Road, International Journal of Sport Nutrition and Exercise Metabolism, 29(2), 130-140.
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Heather Hart is an ACSM certified Exercise Physiologist, NSCA Certified Strength and Conditioning Specialist (CSCS), UESCA certified Ultrarunning Coach, RRCA certified Running Coach, co-founder of Hart Strength and Endurance Coaching, and creator of this site, Relentless Forward Commotion. She is a mom of two teen boys, and has been running and racing distances of 5K to 100+ miles for over a decade. Heather has been writing and encouraging others to find a love for fitness and movement since 2009.