Waterlogged Part II: Trials, Questions, and Suggestions Regarding Hydration and Ultramarathons

Stay the CourseMichigan Bluff, CA. May 20, 2012. It’s day two of Michigan Bluff Training Camp – the annual Western States training week. Relaxing in Carol’s house on the corner of Michigan Bluff Road and…the Western States Trail, I lazily pull out a rather thick, heavy paperback nestled deep the backpack, adjacent Seinfeld and The Office DVD sets. The DVDs beckon, but the book intrigues.

I opened. I read. And read. I couldn’t put it down.

I plowed through Waterlogged (initial iRF Waterlogged review and discussion) and, as soon as the words lifted off the page, I began talking the ears off of veteran ultrarunners Craig Thornley and Meghan Arbogast, me with the passion and giddiness of scientist having a “eureka!” moment.

“Have we been off base? I have I been doing it all wrong?” I wondered.

After that first night, I began the Experiment of One, applying Noakes’ recommendations to the T:

  • Drink to thirst
  • No salt
  • Steady stream of sugar

And I felt great. I ran nearly two hundred miles over those seven days, including 48-mile effort from Robinson Flat to the River on the last day of camp. Besides a half-a-pastrami sandwich and a Pepsi, I had only gels and water.

I was ready. But could I really go with less water, more sugar and…gasp…no salt?

I need more answers. Two weeks before WS, I went straight to the source. I sought out Dr. Noakes, himself:

Q&A with Tim Noakes, MD

iRunFar: You noted that, in the vast majority of cases, additional sodium supplementation is unnecessary – outside of “daily intake.” Given that most folks ingest more than 5 grams of sodium per day in a “typical Western diet,” what do you recommend for supplemental sodium in all-day races, such as Western States 100, that take 16-30 hours?

Tim Noakes: No need to take anything since the body starts with the excess from the previous day’s intake and is in the process of excreting it during the race. Adding any additional sodium simply increases the load that the body must get rid of.

iRF: What are your thoughts on the notion that one must maintain internal fluid volume to sustain blood circulatory volume? Do weight loss percentages beyond the previously accepted 2% have any effect on blood volumes or blood pressure?

Noakes: The key question is whether those losses impair performance, not what they do to the circulation. We routinely measure weight losses in excess of 10% in winners of marathon and ultramarathon races. I do not see any evidence that weight losses in excess of 2% impair performance. Rather I suspect that this degree of weight loss is beneficial since it lightens the load that must be carried.

iRF: Rhabdomyolysis and renal failure are prominent concerns with 100-mile ultrarunners, with several notable cases over the past five years in the sport. What does the research or current medical theory state is the primary cause of “rhabdo?” How does hydration and electrolyte levels possibly impact rhabdo? What about NSAIDs?

Noakes: Rhabdo has to be due to a genetic disorder since it occurs so infrequently. Since everyone loses weight and electrolytes and many ingest NSAIDs without developing rhabdo, the cause has to be something else. Certainly hydration has never been shown to have anything to do with the condition. People lost in the desert die from kidney failure without rhabdo (as far as I know).

iRF: There’s a belief out there that one must drink copious fluids and “pee a lot” to ensure ongoing kidney function during and after long ultramarathon efforts. What, if anything, can runners do to ensure they’ve got well-functioning kidneys during competition?

Noakes: We showed already in the 1980s that the kidneys are barely affected by running marathons. The effort is so submaximal that the kidneys are in no distress. So there is nothing that has to be done to keep the kidneys working during a marathon – other than to drink to thirst.

iRF: You noted a “cultural difference” regarding hydration and salt supplementation amongst California-based ultramarathon races. Can you expand more on that – those differences between ultra races in other parts of the world with similar climates and conditions – and what could be done differently in those races to ensure optimum performance and health?

Noakes: South Africa and New Zealand runners have been warned since the early 1990s of the dangers of overdrinking. But in the US, the sports drink industry drove a different agenda and wanted runners to drink as much of their product as was possible. As a result US runners were conned to believe that if they did not drink “as much as tolerable” they would at best have a poor race and at worst die from dehydration. Instead, this advice caused an epidemic of hyponatremia and poor performances since we now know that athletes who drink ahead of their thirst impair their exercise performance.

iRF: The research studies cited in your book find little to no impact of hydration on core body temperature. What advice could you give ultrarunners in mitigating heat stress while maintaining consistent running performance, especially in hot weather 100-mile races over rugged terrain?

Noakes: The core temperature response to exercise is determined by the rate of doing work – that is the speed at which you run. The running speed is so slow (relative to maximum capacity) during a 100-mile race that the core temperature will be low in such races. So there is no need to do anything other than running at the speed that your body tells you to run at.

iRF: You also touched briefly on the association between hyponatremia and muscle cell breakdown (as measured by creatine phosphokinase blood levels). Can you expand more on that, what the research has found, and what the current theory is relating the two?

Noakes: It does appear that there is a link between hyponatremia and muscle cell breakdown. Why this happens is still not known.

iRF: Races such as Western States 100-mile have medical checkpoints, where runners check-in with medical personnel and, among subjective questioning, submit to weigh-ins, comparing pre-race weight to current. Given the research findings that dehydration does not significantly impact core temperature, and that certain levels of dehydration appear to be optimal, what should both competitors and medical staff, alike, be monitoring at medical checkpoints?

Noakes: The only variable that one must avoid is a gain of weight. All else is not particularly helpful. A recent study found that runners who lost significant weight were more likely to finish than those who loss less weight. The blood pressure measurements are also not particularly helpful. Provided the athlete is able to run, has no symptoms and is not confused, I would let them continue.

My Experimental Western States Plan

There it was, laid out plainly:

  • Drink to thirst; I don’t need water to maintain temperature, circulatory volume, or kidney function.
  • Take no salt; we simply don’t need it to maintain blood sodium levels.
  • Get steady sugar; the one true performance-enhancer.

The plan for Western States was this:

  1. Hydration packs. The tipping point to using hydration packs instead of conventional hand-held bottles was this interesting notion: when we have something in our hands, we tend to consume it, regardless of need. Think about being in a tavern, beer in hand: do you drink it because you’re thirsty, or because it’s there? What about that bowl of candy on the desk in your office? In order to truly drink to thirst, I figured having water readily available – but not in hand – would rule out that drink-in-hand psychology.
  2. Steady stream of sugar. Noakes recommends 60g (to upwards of 100g) of sugar per hour. That’s 3 gels an hour, solid. Knowing I’d be out there all day, and likely running harder than I’ve ever run, I set a repeating watch timer for every 19 minutes, with the intent on taking a full gel with each interval.
  3. Salt-free. I was most uneasy about this. Sure, it worked in training. And it’s tough to argue 30 out of 31 studies showing increases in blood sodium across marathon and ultrarunners who simply drink to thirst and don’t supplement. Even tougher to argue the foremost authority in hydration research in the world! But I’ve been a salt addict. My plan was to take none, but – being the de facto Boy Scout that I am – I was prepared with a small cache of 3 S-Caps in each hydration pack…just in case.

My Western States Reality

Western States 2012 was a race to remember for many, myself included. I ran hard, but conservative through the high country into Robinson Flat (mile 30), sticking to the plan. However, running the flat from Miller’s to Dusty Corners (mile 38) – I felt…”down.” Not cramping, not dead-leg, just…down. I felt off, mentally, and my legs had no pop. I was running 8-minute miles on a section where the ten guys in front of me were running sub-sevens. I was drinking to thirst, I’d eaten a lot (two PB&Js and a candy bar in the last 7 miles). What gives?

I’d been running for five hours, hard. No salt.

Damn.

I reached into the hydration pack to find my mini-pouch of S-caps. I bit down. It tasted good.

With the next thirty minutes, two interesting things happened: My brain and legs returned to life, and my stomach felt much better. I took a second S-cap just before Last Chance (mile 43) and within two miles felt the strongest I’d felt since the first hour of the race.

For the rest of the race, I took an S-Cap about every 45-60 minutes. I continued to drink to thirst and maintain steady sugar intake.

As my race report – and race results – has pointed out, I had a good day. Compared to my 2011 WS race, when any amount of fluid or salt was repulsive, it was a great feeling to run hard in the last twenty miles and have water “taste good.” In the last ten miles, I increased my gel intake to four per hour. The majority of my fluid came from washing down gels and the odd soda at aid stations.

After finishing, my blood sodium was 140 mmol – in the meat of the normal range.

To review:

  1. Drinking to thirst. Worked incredibly well. I drank only when I felt like it – or when I was washing down fuel. Indeed, Noakes talks about natural rehydration, and how it is always accompanied by food – not necessarily salt. Thus, I felt it worked excellent to take in fluid when I was ingesting food.
  2. Sugar. My three gels an hour was effective, but I neglected to take solid food early. I feel some bananas or breads early would have prevented some GI rebellion in the middle miles.
  3. Salt. Tough one. I went 37 miles and more than 5 hours with no salt. But that mental and physical “down” I experienced – that was gradually improved with sodium intake – is difficult to explain. Devil’s Advocate: Was it placebo effect that I felt better? Was it because I slowed down, that my body naturally rebounded? Or is there an alternate avenue by which sodium provides real physiological benefit?

The Salt Mystery

So, where do we stand with salt? I wanted to believe it wasn’t needed. I tried. But I used it, and – as scores of iRunFar commenters argued – it helped.

I went back to Dr. Noakes with more questions:

Tim Noakes (on why hyponatremia rates have fallen the past two years at WS): First, I suspect that runners are now drinking less in the Western States and that is the reason why the incidence of EAH is falling as you clearly also conclude.

iRunFar: Besides a pure placebo effect, might there be another mechanism (neurological, neuromuscular) by which we gain benefit from ingesting salt? Has that been examined as of yet?

Noakes: Biologically, there is no reason to suspect that it works by preventing sodium deficiency, since it is not possible to become sodium deficient even in the Western States race. There is this additional store of sodium that we access when required. The low incidence of EAH in ultradistance events (historically and in races like those in South Africa and New Zealand where overdrinking is not promoted) even when sodium is not ingested shows that sodium deficiency is not a common feature.

Thus I would conclude that if sodium ingestion improves performance it is working in a way that is unrelated to the reversal or prevention of a sodium deficit.

However, it is clear that sodium has a major stimulatory effect in the brain as shown by the sodium ingestion (pickle juice) breaking the cramps study discussed in Waterlogged.

So I would argue that if salt ingestion does improve performance, then it is by a centrally acting brain effect that is different from a placebo effect. Of course, there may also be a placebo effect, as well.

There are studies showing that sodium ingestion improves performance – studies coming out of New Zealand. They need to be repeated. We did not ever study the performance effects of sodium ingestion – only the physiological effects and we found those to be disappointing. We need more studies of this possible effect.

So, yes, there may definitely be another mechanism by which sodium ingestion could affect performance acutely – i.e., within minutes of ingestion – and that would most likely be a central brain effect much as glucose ingestion does the same. Interestingly salt, fat and sugar are the three addictive foodstuffs and that may be the link to acute changes in performance when they are ingested.

Those statements were reassuring to read: that salt may work…but we just don’t know why. Yet.

Hyponatremia and Western States – Past, Present, and Future

I was pleased with my effort at Western States, and the newfound knowledge I gained from Waterlogged. However, in a sport where community means more than any other, I was driven to be sure that everyone – from M1 to 29:59 – was armed with this information.

Dr. Noakes called out “Northern California Ultramarathons” as being ground zero for the hyponatremia problem: both Western States and Rio Del Lago were cited with hyponatremia rates in excess of 30% (Rio, in 2008, had an incredible 50% rate).

Is this uniquely a “Northern California” problem? Unlikely. It’s simply that the vast majority of all ultramarathon research comes from Western States. A survey of other hundreds – namely those in warmer climes – might find similar numbers.

Given the alarmingly high rates of hyponatremia found there, I was driven to know what the Western States Endurance Run was doing to with this information, and how they are addressing their own issues with hyponatremia.

Q&A with Dr. Marty Hoffman, Director of Medical Research, WSER

iRunFar: When did research and testing start at the WSER, and who or what was the impetus for it?

Marty Hoffman, MD: The WSER has a long history of scientific inquiry that began with the interests of Dr. Bob Lind [the first medical director of WSER]. Unfortunately, much of the early work did not end up in scientific publications. It was around 2002 when aggressive scientific work began, and, by 2006, we started to see a number of scientific publications arise from work performed at the event. Following the 2005 event in which I performed some pain perception research, I suggested a more formal research program at the WSER to oversee and promote the process. By the 2006 WSER, we had in place a mechanism for funding research at the event and a research committee composed of an international group of scientists to review proposed studies. Part of the mission of this program was also to assure that research performed at the event would likely contribute to our scientific knowledge, and that mechanisms would be developed to return this new information to the runners. Since that time, research at the WSER has accounted for approximately half of all scientific papers related to ultramarathon running.

I became interested in investigating exercise-associated hyponatremia largely from Brian Morrison’s hyponatremia incident at the 2006 WSER. Our initial study was planned for the 2008 WSER, but you will recall that that was the year the race was cancelled due to nearby fires. It turns out that our initial study was actually performed later in the year at the Rio Del Lago. Earlier in 2008, Dr. Tim Noakes had connected me with Dr. Tami Hew-Butler, one of his former doctoral students who had returned to the United States. I invited her to the 2008 WSER to see the event, and with the intent that she would subsequently organize some studies in future years. She didn’t get to see a race, but she got a feel for the event, and for the 2009 WSER, she organized an international team of investigators. We’ve basically been collaborating since. Much of the work of this group has been related to exercise-associated hyponatremia, but we have also been examining fluid and nutritional requirements, rhabdomyolysis and acute kidney injury. We have other research groups and collaborators that have been examining characteristics of ultramarathon participants, cardiac function in ultramarathoners and foot strike pattern during ultramarathons.

iRF: In your 2010 paper, Hyponatremia in the 2009 161 km Western States Endurance Run, you noted a 30% rate of hyponatremia among your sample of 47. Does this 2009 result represent an anomaly amongst your previous data, or do other years also demonstrate such elevated rates?

Hoffman: It seems that 100-mile ultramarathons in northern California are the mecca for exercise-associated hyponatremia as we’ve found much higher rates in our studies at these events than has been observed anywhere else in the world. In our initial study at the 2008 Rio Del Lago, we found that 51% of the study participants had exercise-associated hyponatremia at the finish. Then, at both the 2009 and 2010 WSER, rates were 30%. Interestingly, the 2011 and 2012 events have had much lower rates of 6% and 5%, respectively. An obvious question is why have the rates been lower the last two years? Certainly the cooler ambient temperature conditions may have played a role. We would also like to think that our educational efforts may have had an impact, as well.

iRF: Your WSER research team has published some thought-provoking studies in the past three years. Findings that come to mind include your studies of the ’08 Rio Del Lago 100 and the ’09 WSER that concluded that changes in weight cannot predict hyponatremia, and the study on the relative effectiveness of treating hyponatremia with a 100mL IV versus oral salt. How much do your research findings, or the data you collect each year affect the medical recommendations for the Run?

Hoffman: Indeed, because of our research, the medical guidelines at the WSER have been adjusted. The work of Dr. Noakes and his colleagues has shown that one is more likely to develop exercise-associate hyponatremia when there is weight gain. Interestingly, this is not the case in our environment. For instance, our work has shown that roughly a third of runners who are hyponatremic at the finish have lost over 3% of their body weight, and only about 20% have gained weight. As such, weight change appears to be of little value in determining who might be likely to be hyponatremic. Besides our work related to hyponatremia, we’ve also observed that some of the top runners lose more than 5% of their body weight without evidence of issues. So, for the 2010 event, we completely removed from the weight change guidelines any criteria for holding a runner based upon weight change. These guidelines provided to the medical and aid station staff basically specify that weight loss of up to 3-5% is appropriate, less than this should trigger a recommendation to consider reducing fluid and sodium intake, and more than this should trigger a recommendation to consider increasing fluid intake, and possibly sodium intake, as well.

Our efforts have also resulted in some changes in our medical treatment at the WSER. There have been several reports of hyponatremic marathon runners dying after being treated with IV normal saline. Actually, it’s been more than a couple decades since we’ve had some evidence that such treatment can be disastrous. Unfortunately, even now there are still some places where the usual treatment for exercise-associated hyponatremia is isotonic saline. Fortunately, there have not been any deaths of ultramarathon runners from such treatment as far as I am aware, but I think that simply means that we’ve been lucky so far.

The proper acute management of symptomatic exercise-associated hyponatremia is now known to be a small bolus of hypertonic saline, either IV or orally. Our treatment trials at the 2009 and 2010 WSER contributed to this knowledge. As a result of this information, we now have guidelines at the WSER that runners are not to be given large volumes of IV fluids without knowledge of their blood sodium concentration. We also now have hypertonic saline available for proper management of exercise-associated hyponatremia.

Q&A with Kerry Sullivan, MD – Medical Director, WSER

iRF: What does the WSER recommend for runners looking to avoid either dehydration or over-hydration and hyponatremia?

Kerry Sullivan: WSER currently recommends: Drink to thirst using the electrolyte drink of your choice. The Race provides Gu2O along the course.

iRF: In the 2012 WSER, there was a notable case on a runner held at an aid station for over two hours due to apparent weight gain of less than 5%. Does the WSER have standardized guidelines that medical captains must follow to determine when to hold, release or pull a runner from the race? If so, what are those guidelines?

Sullivan: WSER relies on clinical acumen, rather than absolute weight gain or loss, when deciding whether to recommend that a runner sit for a while. When a runner looks unwell or their weight is significantly up or down, we encourage a runner to rest and recoup, not drop. We know from experience that a period of rest usually improves their status, making it safer for them to continue on.

iRF: In Dr. Noakes’ book, he discusses how hyponatremia is commonly misdiagnosed – either as dehydration or heat stress – and mistreated – typically by administering hypotonic IV fluids. What criteria do WSER and its medical captains use to diagnose hyponatremia, and what methods do they use to treat it?

Sullivan: Marty [Hoffman]’s data have been invaluable with respect to hyponatremia. We start with medical evaluation of the runner – are they mentating, urinating, vomiting, edematous, weak, et cetera. We keep hyponatremia in mind. If a runner looks unwell, we no longer assume it is simple dehydration. We are judicious in our use of hypotonic IV solutions. At the finish line we have an i-Stat to check the sodium. If the sodium is low and the runner is having extreme symptoms (changes in mentation), we would start an IV of hypertonic saline and arrange ambulance transport to the ER.

Leading the Charge: Western States as the Leader in Best Fueling Practices

Western States is regarded highly as the grandfather of hundred mile races, the de facto national (if not world) championship hundred, and a leader in ultramarathon racing. Commensurate with that reputation, Western States needs to be at the forefront of this latest research.

More importantly, it needs to adopt a consistent message. Throughout the Western States website, there are conflicting messages regarding nutrition recommendations.

My recommendations for the Western States Endurance Run:

1.)   Adopt and profligate the findings of Noakes, Hoffman, et al. regarding the role of water, sodium and fuel, namely:

  • Drink to thirst
  • It is OK to drink only water – just remember Rule #1
  • Take steady calories throughout the day, the earlier, the better (see Hoffman’s research)
  • The role of sodium is so far unknown. Take sparingly. Do not expect it to solve all your problems: research has shown it does not aid in performance, nor does it prevent hyponatremia.
  • The only prevention of hyponatremia is to drink to thirst and avoid excessive fluid intake.
  • It is unnecessary to push fluids beyond thirst – before, during, or after the race.

2.)   Prioritize the medical risks, from highest to lowest.

Western States puts significant emphasis on two medical events that occur with incredible rarity: heat illness and kidney failure.

The false belief that hydration prevents heat illness is so strong that it drives people to drink more than they need. Heat management is important, but orders of magnitude less than believed.

According to Noakes’ research, heat stroke (measured by a core temperature over 41C) has been documented only six times in the past hundred years in events of marathon or longer. Six. In a hundred years. It’s likely been wrongly diagnosed (along with “the nondisease of dehydration,” as Noakes calls it), thousands of times.

Western States needs to de-emphasize the “risk” of heat illness. Instead, it merely needs to state, “If it gets hot, slow down. Stay cool using evaporative cooling methods: dousing, ice bandanas and hats, etc.”

Kidney failure – defined as a measurable loss of kidney filtration rate – is also extraordinarily rare: on the order of 1% per year, or less. According to Hoffman’s findings, it is largely associated with inadequate training, running to fast, and NSAID use. Hydration, so long as one is drinking to thirst, has no effect on the incidence of kidney failure. Rhabdomyolysis might.

To our knowledge, no one has ever suffered full and permanent kidney failure as a result of running an ultramarathon,

Prioritize hyponatremia: given that it is found at 4-6% rates at best – and up to 50% at its worst – this medical condition should be emphasized most strongly: at best it will ruin your race; at worst, it can kill you.

Implore runners to drink only to thirst, to avoid drinking any fluid to excess or beyond thirst, and warn them of the signs and symptoms, and the consequences, of hyponatremia.

3.)   De-emphasize post-race fluid-pushing.

Throughout the website and the participant guide, it states that runners should “continue hydrating for several days until urine is light yellow and normal frequency.”

Recommending fluid-pushing post-race will, at best, slow recovery – whether or not they’re hyponatremic, post-race. At worst, it could create hyponatremia.

To reiterate: according to the bulk of research, neither urine frequency nor color indicates kidney function. A simple recommendation of “drink to thirst” is all that is needed.

Indeed, Noakes noted that most of our rehydration occurs when we ingest food. Given the intense demands on the metabolic systems, a recommendation of “ingest calories as soon as possible following the Run” will ensure glycogen restoration, along with typical dietary fluid intake that naturally goes along with that food.

What We [Probably] Know – The Take-Home Lessons

Through it all, here is what the lessons of Waterlogged, and a decade-plus of research at Western States, have shown us:

  1. Drink to thirst! Drink to thirst! If seventy years of research, and a 400+ page review of it by Tim Noakes in Waterlogged, can be distilled to three words, those are it. Don’t fear dehydration. Even if you become deficient enough to impair performance, water is quickly absorbed and any ill effects are short-lived. But over-hydrating can take hours – or days – to reverse. Drink to thirst!
  2. Keep the stomach turned on and the calories streaming. Food is one substance that the body easily deals with in excess (the obesity epidemic is ample proof of that). Individualize: eat what works for you. Unlike water (and salt), carbohydrates are much slower acting and, when in deficit, can be very slow to replace. Keep the calories flowing!
  3. Salt probably helps – we just don’t know why. It’s not because of blood sodium. But as Dr. Noakes theorizes, there might be a brain or neurological action wherein salt improves performance. We just don’t know for sure yet.
  4. Be minimalist, especially with the things the body doesn’t easily handle: water and salt. Most of us train with minimal salt and water, even on long runs. Thus, it doesn’t make sense to radically and regimentally increase these things in an ultra. Listen to your body!

I hope these works have been as impactful and helpful to you as they have for me. Use science to fuel your passions, but never stop that “experiment of one.”

Call for Comments (from Bryon)

Discuss.

[Disclaimer: The contents of this column as well as the author’s comments are provided for general informational purposes only and are not intended as a substitute for professional medical advice. Do not use the information on this website for diagnosing or treating any medical or health condition.]

Joe Uhan

is a physical therapist, coach, and ultrarunner in Eugene, Oregon. He is a Minnesota native and has been a competitive runner for over 20 years. He has a Master's Degree in Kinesiology, a Doctorate in Physical Therapy, and is a USATF Level II Certified Coach. Joe ran his first ultra at Autumn Leaves 50 Mile in October 2010, was 4th place at the 2015 USATF 100K Trail Championships (and 3rd in 2012), second at the 2014 Waldo 100K, and finished M9 at the 2012 Western States 100. Joe owns and operates Uhan Performance Physiotherapy in Eugene, Oregon, and offers online coaching and running analysis at uhanperformance.com.

There are 68 comments

  1. Andy Blow

    Hi Le Manchot,

    Thanks for the comments. I've spoken with Dr Raj Jutley (our CMO) about the statistics and the numbers behind them and details are below. I'm not as well versed in statistics as either you or he but let me know if this answers your query and I can always ask for more detail if needed, or put the 2 of you in touch?

    We took 342 sweat tests (most of our early subjects, all athletes, mostly endurance athletes) and conducted simultaneous questionnaires.

    Subjects were asked if about their cramping experiencing during exercise and whether they cramped NEVER / RARELY / OFTEN or ALWAYS

    Results:

    NEVER (n=146, mean 42.4 mmol/L sweat sodium) compared to OFTEN/ALWAYS (n=71, mean 52.5 mmol/L sweat sodium)

    Total population mean = 46 mmol/L

    Statistical test = Two Independent Sample Wilcoxon Rank Sum Test P-value < 0.001

    As regards publishing – Dr Jutley says he does intend to publish but has not done so yet due to time pressures and other work commitments (his position with us is not full time).

    In terms of the exact mechanism behind this….we are not sure at this stage. However as I said in my original post we are seeing what we believe to be a link between the level sodium loss and the incidence of cramping and/or poor performance in longer and hotter events. We're certainly not saying it is black and white, or indeed the same for all individuals, however there does appear to be a trend worth looking at more closely. We'll be continuing to investigate this further with research where we can and also in collating anecdotal feedback from athletes we test.

    My own feeling is that we perhaps all have something of a threshold of tolerance for sodium loss, below which performance is negatively affected (sometimes with symptoms such as cramping, sometimes not). However many factors influence this including rate of sodium loss in sweat, level of sodium intake (habitually in normal diet and acutely during races), ability to tap into any proposed sodium stores in the body, variances in the threshold level between people, level of fluid intake and so on.

    Whatever the mechanism I am firmly of the belief that the whole hydration/electrolyte balance and replacement equation needs to be very individualised and than a mix of scientific 'knowledge' and trial and error is the best way for an individual to get a handle on what works best for them.

  2. Andy Blow

    Hi David – this is an interesting paper that discusses the possible basis for sweat sodium levels varying in individuals with and without CF:

    Low abundance of sweat duct Cl− channel CFTR in both

    healthy and cystic fibrosis athletes with exceptionally

    salty sweat during exercise

    Mary Beth Brown, Karla K. V. Haack, Brian P. Pollack, Mindy Millard-Stafford and Nael A. McCarty

    Am J Physiol Regul Integr Comp Physiol 300:R605-R615, 2011. First published 12 January 2011; doi: 10.1152/ajpregu.00660.2010

  3. Lee

    Hi Joe,

    Could it be that your stomach shutdown after the two PBJs and candy bar? That's a lot within 7 miles. Could be why you felt down and it was the time it took to digest them that brought you back not the salt. I find that when I eat too much PBJ at one time I get sluggish until I fully digest it and then it gives me a great kick of energy.

    The stimulus effect Noakes talks about as a possible alternative explanation for performance improvement suggests that tasting the salt as you ingest it might send a stronger and quicker signal to the brain. You might not even have to swallow it!

    Cheers,

    Lee

    1. OOJ

      Lee,

      Thanks for the post. I never felt nauseous. My stomach (thankfully) is awesome almost all the time…except when I'd given it nothing but gels for the first 30+ miles. If anything, the real food made it feel better. What the food *didn't do* was reverse my general energy malaise.

      Per the "taste", you're dead-on. This was the theory behind the "pickle juice" study he mentioned in the interview: that only through a taste/neuro connection could something be so fast-acting.

  4. KenZ

    Next data point: did Chimera 2012 (100 miles, 21,500 gain/loss) in November. I brought 5 S-caps with me 'just in case.' Used none of them. Ran a reasonably fast 20:33. Zero issues with cramping. Zero. Obviously, aid station food has some salt in it, but wasn't seeking out the salty stuff in particular.

    It may matter person to person, but I've found _FOR ME_ over the limited years I've been doing this, that when I cramp it's because I'm simply overextending myself and pushing too hard (and it usually happens around 4-5 hours in, always in a 50 miler which is short enough that I can be dumb enough to overextend that early). Initially, when I'd start to cramp in these situations, I'd slow down, pop some MORE S-caps (because I was doing 1-2/hour already), and slowly the cramping would go away. But note that I was also slowing down! Now, I just decrease the intensity a hair; doesn't take much, and the cramping is averted. For me, salt appears to have nothing to do with it.

    Will keep trying this out next year. But, will also likely always carry 5 or so S-caps with me… just in case. The placebo effect is strong!

    1. OOJ

      Great feedback!

      What I would speculate is in the "over-extending", the issue might be a biomechanical one (muscle inefficiency) rather than physiological (energy systems, eletroyltes, etc). By slowing down, your mechanics return to their more efficient state… Food for thought…

  5. David E

    There are a lot of variables here. Take sweat rates and sodium concentration in sweat. There is considerable variation due to genetics, and considerable variation due to heat training. Furthermore, those on a high salt diet will excrete more sodium, and those on a low salt diet will conserve it. That is why no formula can tell you how much electrolyte to take at a given race.

    I find when I'm low on sodium, I am thirsty and I pee a lot, every 20 minutes. Taking sodium fixes that. Also, I must take sodium right around the end of a hundred miler, or I'll get sick right afterwards. So we all have to be aware of our body's reactions to varying amounts of water and sodium under varying conditions — everyone is different.

  6. Mark Beattie

    Certainly not while warm weather trail running, but most cold weather expeditions and Arctic explorers carry sticks of butter or some sort of solidified fat and eat a large percentage of that as part of their diet, I want to say at least %30 of calories from it while expending many calories on cold expeditions.

    I believe the diet of northern native peoples (Eskimo-Aleut, Inuit, etc.) has been shown historically to eat a (relatively) higher percentage of fatty foods. If this shows anything, I'd think it'd be that humans are a highly adaptable species and can figure out what works best for them in varied environments.

  7. OOJ

    It's worth noting that a major area of focus recently for Dr Noakes is the benefits of a high-fat, low-carbohydrate (sugar) diet – for both the general population and athletes.

    However, he's noted in his previous works (Lore of Running, most updated edition – 2003?) that the primary role of sugar is for brain/liver glucose levels – not the muscle. This would align with the notion that fatty fuels are usable for prolonged exercise, so long as it is sufficiently low-intensity.

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