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On hydration, research, media hype and contrarianism

August 26, 2012

It’s been a while since I blogged about anything, largely because Twitter has served that function perfectly well during my first year as a father. Alex’s birthday is on Tuesday, so I thought I’d celebrate by dusting off the blog and saying something about science.  So with a bottle of the (now) local brew, Spitfire, in hand, here goes…

In late July of this year, the BBC broadcast one of the most biased programmes I’ve ever seen. I love the Beeb, and the usual problem for them is not bias but false balance, but that’s a whole other blog post. The programme in question was Panorama, and the topic was sports products. The basic narrative was that most sports products lack any scientific basis and those that are supposedly backed by science (sports drinks in particular) are based on poor quality evidence sponsored by industry, which leads to widespread publication bias.  Watching the programme as an outsider, you’d be forgiven for thinking that sports science research was being conducted by either clueless muppets or industry shills.  I hope he won’t mind me singling him out, but David Briggs commented on Twitter (I paraphrase) “[Panorama] is like a Skeptics in the Pub, evidence or GTFO”.  I agree; as an exercise in dismantling marketing hype, the programme was an epic triumph.  However, knowledge of the source material and the background of some of the “talking heads” strongly suggests something altogether less palatible was going on.

The source

The BMJ published a series of free articles to coincide with the Panorama broadcast, and they make universally depressing reading.  They included a commentary by Tim Noakes, a feature article by Deborah Cohen, and several articles by a team of researchers led by Dr Carl Heneghan.  The most important for the purposes of this blog was their “40 years of sports performance research…” article, which laid out why sports performance research was, in their analysis, largely of such poor quality that the results are largely uninterpretable, and certainly not generalisable. There have been a number of responses to these articles by those involved and those named in the articles as being in the pay of the sports drink industry, and I will not repeat their critiques. They are well worth reading on their own.  I do not intend what follows to be a systematic analysis of the source material as a result, I simply wish to raise some issues that have not, in my view, been adequately or completely addressed.

With regard to the quality of sports performance research, the charge that it is poor stings me personally, as I have been involved in studying sports performance (not sports drinks but other stuff, see here). Many of the criticisms, such as low sample size and the use of poor surrogate measures, also applies to my research, so I’d like to briefly address them.

In Heneghan’s paper (above) they suggest that, from epidemiological research, “small” sample sizes are those with fewer than 100 subjects in each arm of an experimental trial.  But sports performance research is primarily laboratory-based, although with GPS and power-measuring devices field studies are becoming more common. But there really is no substitute for getting in the lab and measuring things in a carefully controlled environment if you want to learn anything about physiological mechanisms.  If you disagree with this, it’s probably because you view the performance bit being more important than the physiological mechanisms.

My bias is the other way, but both approaches have an abundant literature base.  Either way, you are rarely going to find 100 or more subjects in a sports physiology paper.  There are two principal reasons for this. First, there simply aren’t enough people willing to participate in physiology studies involving exhaustive exercise and (often) invasive procedures such as blood sampling and muscle biopsies. Secondly, sample size is determined by considerations of measurement variability and effect size. If the former is small and the latter large, it is quite possible to achieve a desired level of statistical power with fewer than 20 subjects.  It would be unethical to test another 80 subjects if 20 would do.  Anybody working in the field would know this as we have to convince ethics committees that we need as many subjects as we think we do. My highest n so far has been 23!

A secondary reason for the low sample sizes in hydration research in particular is that they are incredibly time consuming (by human performance research standards). A well-controlled fluid balance study will require the subject to compile a lead-in food diary (repeating that diet exactly if repeated visits to the lab are performed; they frequently are), at least 1 hour of preparation in the laboratory (to establish the baseline), pre-test measures, exposure to the environment before exercise commences, and then often exercise lasting 1-3 hours to exhaustion, followed by removal from the environment until core temperature and/or hydration status has reached pre-defined cut-offs to allow the subject to safely leave the lab. All the while, all fluids consumed and all urine produced needs to be monitored, and the subject repeatedly weighed (nude). Suffice to say these studies can take all day and several lab staff to complete one subject’s test, of which there may be several.  As an example, to perform one placebo-controlled study in Aber, I had to perform a pre-test, two familiarisation trials (to exhaustion), followed by two further trials with different drinks. Each visit after the pre-test started at 7 am and I left the lab at 2 pm.  The scientists in question would have needed to work into the evening to analyse the data and clear up. So, 29 hours for n=1!

Poor surrogate measures

A second suggestion of Heneghan et al. was that too many studies performed time to exhaustion trials rather than time trials, the latter being more like the “real world” and therefore better.  I have a bit of a problem with this too, as it is not only bollocks, but clearly demonstrable bollocks.  Several studies have shown that although time to exhaustion trials are more variable than time trials, the effect of a treatment on both is about the same.  Amann et al. (2008) clearly demonstrated this, and my own research shows that priming exercise increases time to exhaustion by more than 10%, whereas the effect on time trial performance is about 2-3%. Both results are statistically significant and equally meaningful. There is, therefore, plenty of evidence that time to exhaustion and time trials are similarly sensitive.  Time trials have the advantage of being a close simulation of actual performance, but have the very real disadvantage of producing large amounts of data that cannot be directly compared with other conditions because the work rate is, by definition, uncontrolled.  On the other hand, time to exhaustion suffers from being unlike any event besides certain parts of “World’s Stongest Man”, but is the method of choice for those of us wanting to understand the physiological response to exercise.  Heneghan et al. should have known this from even the most cursory glance at the literature.  As explained below, however, a cursory glance is not even what they gave it.

Poor methods of the BMJ articles

The most disappointing aspect of the analysis of Heneghan et al. is that they did exactly what you would do if you were basing a Skeptics in the Pub talk on sports drinks – examine the claims the manufacturers are making, and see if they stack up.  However, as illustrated in a number of responses to the articles, they went far beyond this in their conclusions, and their methods do not justify them. What they did was ask manufacturers to supply the science underpinning hydration.  Only GSK, manufacturers of Lucosade, got back to them.  They then went about reviewing the articles they had been given, assuming that the quality of the articles would be the same for all other sports drinks, without actually reading any of those referring to other drinks. Nor did they read any other hydration-related papers, as you’d need to do if you were being systematic.  Had they done this, they’d have found dozens of papers from the 1940s and 1950s on hydration, pre-dating the formation of the sports drink industry.  This is because many second world war operational theatres involved significant heat stress and high fluid intake demands.  Logistically, figuring out how to hydrate several hundred thousand soldiers properly was pretty important.  The Journal of Applied Physiology was created, in part, to provide an outlet for this often previously classified research.

The bias and the talking heads

It should be obvious where the bias comes from in the above: ask somebody for evidence supporting a marketing claim, and you’ll get evidence supporting that claim.  If you don’t bother to look for any other evidence, you’ll have a biased and incomplete view of the issue.  This, incredibly, led the feature writer to bring up the issue of publication bias in hydration as akin to that of the pharmaceutical industry.  Publication of positive findings rather than negative findings is a problem throughout the scientific literature.  In order to be published, negative results have got to be unexpected or unusual, and that doesn’t happen very often.  I don’t like that any more than you do, but that’s the way it is for now.  I would just like to point out the key difference between “big pharma” and the sports drink industry.  For the former, there is tangible evidence that negative findings were actively suppressed – Ben Goldacre’s Bad Science book is an excellent primer for that sort of thing.  In the case of the sports drink industry, it’s possible that they have attempted to prevent some negstive studies being published, but there is no evidence for this. More importantly, the product in big pharma can only be got from big pharma.  In the case of the sports drink industry, I urge you to consider the contents of your kitchen. If you have some salt, sugar, sweetener, fruit cordial, a water supply and some form of thickening agent – pectin for example, congratulations, you have the necessary ingredients for a double-blind, placebo-controlled study of sports drinks.

Simply stated, it would be impossible for the sports drink industry to bury negative findings, since anybody with a few quid and some accurate scales can repeat and test the evidence.  Moreover, the vast vast majority of hydration and carbohydrate studies in the literature do not use a commercial sports drink.  Instead, the scientists make their own drinks from clinical-grade ingredients.  If they are using protein or amino acid mixtures, and they have any sense, they’ll also send it for mass spectrometry or HPLC analysis to make damn sure what they think they have they really do have.  Commercially available protein mixtures are notorious for having all sorts of things in them they shouldn’t have.  Caffeine is the most obvious and common example of an unnamed ingredient.  So here is a further problem: if you’re only going to analyse those studies containing a particular commercially-available drink, you’ll miss 90% of hydration research anyway!

The Panorama programme was interesting because it took evidence from relatively few people, the most high-profile of which was Prof. Tim Noakes. It has since transpired that those providing a counter to Noakes’ well-documented animosity to the sports drink industry were either ignored or interviewed and then cut from programme altogether.  It is also obvious from the responses posted on the BMJ site that nobody named as conspiring to pervert the scientific interpretation of hydration research or to suppress results counter to the industry message in the feature article were approached for comment before publication.  It is to their credit that the scientists involved have used the right of reply rather than legal avenues to make their point.

It is unlikely that those reading the articles or watching the programme would know that Noakes’ views on hydration are considered contrarian. I pointed this out to Deborah Cohen on Twitter, during a sometimes heated debate running into the small hours, but we ended on good terms (I think).  Interestingly, Noakes subsequently replied to me – despite not following me and cc’ing Cohen to call me “Unprofessional” for suggesting that he “quote mines” and “cherry picks” in the scientific literature. I’m still not sure how he discovered my feed, and I wouldn’t want to guess here. I did make the claim that Noakes was paid by Powerade to do research. That was false and I am happy to correct it: his lab has received money from a company marketing Energade; he receives no personal financial income from the industry.

Quality of evidence?

Let us end on a lighter and broader note: how do we assess the quality of research?  In the UK, peer review is the way, and so it should be. The fact that this is wrapped up in the terrible mess that is the REF should not detract from that. But contrast this with the following, a written response from Noakes:

” In his rapid response Dr Michael Sawka implies that poor science not conflict of interest issues explains why papers are not accepted by leading journals like the Journal of Applied Physiology and Medicine and Science in Sports and Exercise, the Editorial Boards and review panels of which sometimes contain individuals who have close associations with the sports drink industry. If this is true, relevant papers rejected by these journals must subsequently fail to attract high citation rates when published in other journals.

In fact a number of our papers rejected by those journals were subsequently published elsewhere and have already been cited 50 times or more in the literature. Hence they could not legitimately have been rejected because they were of poor quality. Typical examples include the following four papers1-4 already cited respectively 52, 74, 66 and 55 times according to the Web of Science.”

I’ll not insult your intelligence by pointing out the flaws in this argument.

So there we have it. A programme based on a biased narrative, drawn from the work of researchers who clearly don’t understand sports performance research, and who ignored the vast majority of the literature in any case. The sad truth is that sports science got a good stiff kicking in the process, and it’ll struggle to recover its already meagre credibility as a result.  Now if only sports science had a role to play in, let’s say, a Tour de France victory and 29 gold medals…

Update: 22 September 2012

Recently the BMJ published as surprisingly long list of corrections to the paper of Heneghan et al. mentioned above http://www.bmj.com/content/345/bmj.e6085. These corrections follow correspondence from some authors of some studies rated as at “high risk of bias”, who pointed out that they were, in fact, misclassified. This was based on incorrect assertions of non-randomisation and a lack of blinded, when those studies were in fact randomised and blinded. In respomse Heneghan et al. have downgraded the risk of bias to moderate in these studies, only because the studies do not exhaustively state the methods used to blind and randomise – otherwise the risk of bias would have been rated as “low”. There are likely to be other studies rated “high risk” that are not, but the authors have not contacted the BMJ to point this out. Whether this will, ultimately, alter the conclusions of the BMJ article remains to be seen, but I have not seen such a large number of corrections published in a single paper before.

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12 Comments leave one →
  1. Tim Noakes permalink
    August 26, 2012 6:57 pm

    Please read my book Waterlogged (Human Kinetics, 2012). It is my response to this. Read the book and see if I am contrarian and if I “cherry pick” and “quote mine”. It took me 30 years of research to understand the field and to write the book. I did not begin by believing what I discovered. In the beginning I was just as much a fan of the industry as is this author.

    I dedicated Waterlogged to Dr Cynthia Lucero and all others who have died unnecessarily from exercise-induced hyponatremic encephalopathy, an entirely preventable condition. The book describes what factors caused this condition to develop after 1981 and why our proof of how the global growth of the condition could be prevented, was ignored.

    I still fail to understand why I have to be demonized by persons like the author for pointing out some uncomfortable truths. I believe it is the technique of shooting the messenger so that the message does not need to be heard.

    It would be really great if, for once, people like the author would properly present what is the real message I have tried to present over the past 30 years. Then at least they would be acting honestly.

    Is that too much to hope for?

    • August 26, 2012 10:59 pm

      I would enjoy reading a response from the author after he read “Waterlogged”. I find it all so interesting. I think many people assume Tiem Noakes wants athlestes to drink nothing when that is not the case. From what I have read it is a drink to thirst philosophy and not chugging a drink at ever water stop because you think you need to.

    • August 26, 2012 11:47 pm

      Firstly, I am no fan of the sports drink industry. I am a fan of accuracy and good science. This particular post’s main point is that the BBC Panorama programme and the BMJ articles contained neither of these. The public perception of sport and exercise science in the UK has suffered as a result. You were clearly the highest-profile academic interviewed in the Panorama programme, and your views, and virtually nobody else’s, formed the principal narrative. These are facts, not demonisation.

      With regard to the notion of shooting the messenger so that the message will not be heard, in your case, this complaint is absurd to the very highest degree. You have a 400+ page book recently published on hydration, 62 of your papers contain the word “water” in the title or abstract, and you have, to date, published 444 papers according to PubMed. Add to that the fact that you appeared on national television for several minutes in the flagship current affairs programme of the day, on the most watched TV channel outlining your message, it’s a strange idea that your message is not being heard.

      Lastly, I will treat your comment on my honesty with the contempt that it deserves.

    • August 29, 2012 12:45 pm

      so if we buy your book – your profit greater from this all Tim?

  2. Dr. Philip Friere Skiba permalink
    August 27, 2012 11:24 am

    With respect to Professor Noakes, I wish to offer the following:

    1) Those of us who practice sports medicine are very grateful for his efforts in bringing the problem of hyponatremia to the fore. I have worked in medical tents at some of the largest endurance sporting events in the world (including the NY Marathon). Professor Noakes has fundamentally changed the front-line care provided at marathons around the world. He deserves credit for this. Many years ago, as a medical trainee, I sought out his opinion with respect to a difficult case. He very graciously provided his expertise.

    2) This said, Professor Noakes does indeed have a “well-documented animosity to the sports drink industry,” as well as a tendency to claim that he has been somehow victimized by an industry and establishment that seeks to squelch his message. This claim is not currently supported by evidence. This is not merely my opinion, but one easily found in the field. For example, in one of the more concise available discussions, Shephard (http://bjsm.bmj.com/content/early/2011/09/07/bjsports-2011-090194.short?rss=1) states:

    “…some 50 articles on EAH have been published in the world literature since 1985. Not all of these were concerned with an overingestion of fluids, but at least 22 of the 50 have been authored by Noakes and his colleagues. Two of his articles on this topic have been accepted by the primary journal of ACSM, one by Current Reports in Sports Medicine (also an ACSM journal), and one by the Journal of Applied Physiology. Moreover, Medicine & Science in Sports & Exercise has published a total of 179 articles and abstracts on EAH since 1985, and at least two detailed reviews on this topic have appeared in other vehicles under the aegis of ACSM (Exercise & Sports Science Reviews, and the Year Book of Sports Medicine).” (1)

    Shephard concludes:

    “…the suggestion that the topics of EAH and overingestion of fluids have been obscured by a financially driven agenda shared by sports drink manufacturers, respected sports scientists, the American Physiological Society and ACSM does not withstand close scrutiny.” (1)

    It should be noted that Dr. Shephard:

    “…never received any type of financial support from companies associated with the manufacturing or marketing of sports drinks, nor have I had occasion to edit or referee any of Noakes papers on the question of EAH.” (1)

    While Professor Noakes has offered a number of publications that have provided significant value to the study of the physiology of fluid balance and to the practice of sports medicine, I cannot help but conclude that he sees conspiracy where none exists. I have no opinion on his motivations for this, only the concern that his future (possibly equally valuable) contributions may be marginalized or ignored due to being viewed as a “boy who cried wolf”.

    Finally, readers should note that while I am a sports physician and physiologist, I do not do research on sports drinks and I am not funded by by the sports drink or supplement industry in any way, shape or form.

    1) Shephard, R. J. (2011). Suppression of information on the prevalence and prevention of exercise-associated hyponatraemia. British Journal of Sports Medicine, 45(15), 1238–1242. doi:10.1136/bjsports-2011-090194

  3. Tim Noakes permalink
    August 27, 2012 4:34 pm

    Again my defence is that you should first read Waterlogged before drawing your conclusions. How was it possible that a bogus “Science of Hydration” became universally accepted as the sole truth after 1985? How could an entire profession have been misled without ever questioning what was happening?

    I appreciate that it is rather easier to blame me for “seeing conspiracy where none exists” than trying to understand how it all came about. Had I not stood up for what the science showed me, you would still be managing patients in marathon races inappropriately according to guidelines that are based on that bogus science, rather than on the real science presented in Waterlogged. And patients would still be dying unnecessarily from inappropriately treated EAH and EAHE.

    The question I ask again: What sustained that bogus science that you are thankful I overturned so that you now have the confidence to treat your patients appropriately at the New York City Marathon?

    If the exercise sciences eagerly embraced all truths equally, our findings that EAHE is due purely to overdrinking to which sweat (and urine) sodium losses play no part, would have been integrated into our teaching the moment we made that finding in 1991. Instead only after the publication of Waterlogged has the ACSM agreed to review its 2007 drinking guidelines because of this “new information”. Between 1991 and 2012, 13 athletes or soldiers have died unnecessarily as a result of EAHE and more than 1600 have required hospital care. Some of those who died were mothers with small children. I would guess that those children will also have a degree of animosity when they discover that their mothers died from an entirely preventable condition. So I suspect I am not alone in my disgust at what was allowed to happen.

    Professor Shephard is most welcome to his opinion but he presents no evidence to show that he did any research to detect whether or not a conspiracy exists or existed. He simply checked whether scientific articles were being published. He did not address the question of whether or not that information was actively being conveyed to the general public by those marketing sports drinks or if that information was being incorporated into official drinking guidelines produced by influential scientific bodies.

    Two studies published last year in the British Journal of Sports Medicine and the Clinical Journal of Sports Medicine of runners in the London and Chicago Marathons, reported that the majority of marathon runners in those two countries still do not understand how they should be drinking to prevent EAH and EAHE. How can this be, 21 years after the cause of EAH was established by us?

    Finally I note that Professor Shephard is not averse to publishing articles attacking my views on a range of topics.

  4. Dr. Philip Friere Skiba permalink
    August 28, 2012 11:04 pm

    Professor Noakes,

    You raise a couple of interesting points, and I think readers of this blog would be well-served if we discussed them in greater detail.

    Firstly, I assign no “blame” (to use your term) for you seeing conspiracy where I do not. It is entirely possible you are privy to information not available to me. I simply state that I have not seen any evidence of conspiracy, and other independent academics are of like opinion. I will read your book with much interest and carefully weigh any evidence you may present to support the (very serious) charge of a conspiracy.

    Secondly, you seem to suggest that the publication of your recent book was the impetus for the ACSM “agreeing to review” its 2007 recommendations (1). (My apologies if this was not your intent). However, the public statement from the ACSM does not seem does not seem to view this in quite the same way (2).

    “A new book on sports and hydration – “Waterlogged: The Serious Problem of Overhydration in Endurance Sports” by Tim Noakes, M.D., Sc.D. – underscores concerns about excessive hydration and risks of hyponatremia that were expressed in the 2007 ACSM “Position Stand on Exercise and Fluid Replacement.” While there are points of agreement, the book also takes exception to parts of the fluid replacement Position Stand. *Such editorial comments will be considered as part* of the evolving, state-of-the-art approach to producing evidence-based papers that are the most authoritative, reliable and objective sources of information.” (2) (Emphasis mine.)

    This said, the above reference to your book by the ACSM is of relatively little import with respect to showing the impact of your work. You observe that Professor Shephard did not address whether your work was being incorporated into drinking guidelines. You seem to wish to imply that your work is not being incorporated. Whether Professor Shephard made the point directly or not, readers should note that the 2007 ACSM guidelines do, in fact, offer considerable discussion of the entity of exercise associated hyponatremia (1). This discussion *does* include references from your publications. In fact, reading the evidence statement at the end of the section, we find the following exhibit of how seriously your work was considered:

    “Symptomatic exercise-associated hyponatremia can occur in endurance events. *Evidence Category A*. Fluid consumption that exceeds sweating rate is the primary factor leading to exercise-associated hyponatremia. *Evidence Category A*.” (1) (Emphasis mine).

    Just as importantly, you are listed as the *sole author* of the International Marathon Medical Director’s position statement on fluid replacement in marathon running (6). This was published in the Clinical Journal of Sports Medicine in September of 2003.

    Of course, earlier versions of the ACSM statement left room for improvement. These sorts of publications are necessarily works-in-progress and we expect later iterations to to be better than earlier iterations. For comparison, I have the 1996 version of these guidelines to hand (3). However, Coyle (2004) (4) provides a succinct quotation of the most important (for the purposes of this discussion) bit:

    “In its most recent position stand (1996) (3), the ACSM recommended that: ‘During exercise, athletes should start drinking early and at regular intervals in an attempt to consume fluids at a rate sufficient to replace all the water lost through sweating (body weight loss), or consume the maximal amount that can be tolerated’. This document further stated that ‘individuals should be encouraged to consume the maximal amount of fluids during exercise that can be tolerated without gastrointestinal discomfort up to a rate equal to that lost from sweating’.” (4)

    The position stand clearly states that athletes should only drink up to a rate to that equals the rate of fluid loss by sweating. (That is not to say fluid maintenance to that extent or by that method is necessary or even desirable for optimal performance, of course, but that is not my interest here). The important observation to take away here is that the fragment stating the “maximal amount that can be tolerated” must be interpreted in context of the surrounding information. Our problem (at least, in the United States) was, in my estimation, nothing as interesting as a conspiracy. It was that popular-literature ‘experts’ (perhaps well meaning, but without professional qualifications in medicine or physiology) seized on the fragment alone, and advised readers to drink ‘as much as possible’.

    Combine this tiny bit of information taken out of context with an event full of people with limited training, going slowly and drinking mightily, and we have a stage set for a big problem. This requires nothing resembling conspiracy: just a lot of (again, likely well-meaning) people providing advice above their level of expertise.

    To be fair, we might forgive some of these authors for their misunderstanding. You yourself seem to have taken multiple meanings and been somehow confused by the same statement. Coyle (2004) (4) notes:

    ‘In an attempt to bring attention to the potential for developing hyponatraemia from drinking excessively large volumes of fluid during marathon running, Tim Noakes has been critical of the 1996 guidelines from ACSM (5). Noakes quotes the 1996 guidelines for his statement that ‘athletes are now advised to replace all the water lost through sweating (that is, loss of body weight), or consume the maximal amount that can be tolerated, or drink 600–1200 ml per hour’. It is perplexing to the author of the current review how Dr. Noakes could interpret the 1996 guidelines from ACSM (3) to suggest multiple recommendations, including the notion that athletes drink more fluid than is lost during exercise and therefore gain body weight.’ (4)

    I see your contributions to the field well represented throughout the literature. While in hindsight everyone may wish awareness had come more rapidly, science, medicine, and the synthesis of these factors that comes to embody ‘best practice’ is often a gradual progress. This is not in and of itself indicative of conspiracy. However, as I mentioned earlier, I’ll look forward to seeing any evidence provided in your book.

    In conclusion, please accept my best wishes and my hopes that your new book will continue to stimulate awareness of an important, entirely preventable clinical entity.

    1) Sawka et al. (2007) American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc (39)2, 377-390.

    2) http://www.multibriefs.com/briefs/acsm/positionstands5-8.htm

    3) Convertino, V. A., Armstrong, L. E., Coyle, E. F., Mack, G. W., Sawka, M. N., Senay, L. C., & Sherman, W. M. (1996). American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and Science in Sports and Exercise, 28(1), i–vii.

    4) Coyle, E. (2004). Fluid and fuel intake during exercise. Journal of Sports Sciences, 22(1), 39–55.

    5) Noakes, T.D. (2003). Overconsumption of fluids by athletes. British Medical Journal, 327, 113–114.

    6) Noakes, TD. (2003) Fluid replacement during Marathon Running. Clin J Sports Med. 13(5), 309-318.

    • Havelock Vetinari permalink
      September 1, 2012 2:09 pm

      Your defence of ACSM’s recommendations by quoting “sufficient to replace all the water lost through sweating” is disingenuous. You say that “maximal amount that can be tolerated” must be interpreted according to the context ie. “sufficient to replace all the water lost…”, but considering that, outside controlled laboratory conditions, it is next to impossible for an athlete to determine with any degree of accuracy how much water is lost through sweat (the variable factors are far too many and far too changeable, even during the course of a single event). The clear implication of this is that the only part of these recommendations that can be followed outside laboratory conditions is to drink as much as can be tolerated. This is the only contextual interpretation that provides an athlete with any concrete, usable guidelines. To my mind, their inclusion of the words “sufficient to replace all the water lost through sweating” is nothing more than (if you’ll excuse the terminology) a cover for their asses.

      Then your lot of well-meaning people “…providing advice above their level of expertise…” got the advice they passed on from somewhere. Where did they get it from, and why (if the ACSM was actually aware of the dangers as you seem to imply) was there not a concerted effort to discredit this advice? If so many people were following it, it could certainly not have avoided coming to the attention of ACSM.

      If there actually was a conspiracy in this issue, the beautiful thing is that it didn’t need to be organised or explicit. It may have all started accidentally with Gatorade – some plausible (though dodgy) science used as marketing that led to a critical mass of popular opinion… after that, all the sports drink industry needed was to keep sponsorships coming, and keep up an appearance of scientific credibility… the powers that be will always (as long as the danger element is plausibly low) support the side that will grow their sport, which means sponsorship and publicity – money that comes from the likes of Gatorade.

      • Dr. Philip Friere Skiba permalink
        September 3, 2012 9:16 am

        It is difficult to entertain the charge that I am somehow “disingenuous” from a person hiding behind a pseudonym. (http://en.wikipedia.org/wiki/Havelock_Vetinari).

        This aside, your comment that “it is next to impossible for an athlete to determine with any degree of accuracy how much water is lost through sweat” is frankly “disingenuous”, unless you come from a land that lacks thermometers and bathroom scales. I’ve been training amateur and elite endurance athletes for many years. The range includes those who finish an Ironman just under the 17 hour cutoff to world champions. All of them were / are required to train under a variety of conditions, including those that mimic race day. They weigh themselves before, during, and after sessions. They noting the conditions, their fluid and nutritional intake, their weight, and any outputs.

        Through this process, we are able to devise a personalized, evidence-based hydration strategy. We are also able to identify people at risk for over-drinking (see below) long before they put themselves in any danger. It is this attention to detail that leads to a successful race. It is also well within the ken of anyone capable of training for an ultra endurance event. In my opinion, athletes who do not attempt to discover how their bodies will behave under race conditions *before* the race are choosing to take a risk that I would not take myself.

        For example: As I mentioned above, I consulted Professor Noakes (and an endocrinologist of some repute) several years ago with respect to an elite athlete for whom “drinking to thirst” resulted in massive fluid overload. While the case is too long to relate in detail (and would result in confidentiality concerns), the salient finding was that the athlete repeatedly developed an unquenchable thirst during competition in hot/humid conditions. In many ways, it mimicked the behavior we see in patients with SIADH. Given what we know about hyponatremia, this represents a very dangerous situation, and one that increases with race length.

        This case illustrates several important points.

        1) The reality of the physiology of ultra endurance exercise (particularly in extreme climates) is complex, and any truly complete set of guidelines will require a nuanced approach, rather than sound bytes or artificially simplified rules of thumb.

        2) There exist people who do not over drink on the basis of any guideline or advice, but rather because of an innate mechanism worthy of investigation. Thus, ‘drink to thirst’ represents an incomplete guideline.

        3) Truly minimizing the risk of ultra endurance exercise requires a highly organized, highly individualized approach.

  5. Tim Noakes permalink
    August 29, 2012 9:02 am

    Great reply. Thanks for putting it so well. Actually I am not sure that I ever said there was a “conspiracy”. I suspect that was a term used to label me since labelling makes it much easier to dismiss my arguments as a rant rather than a serious scientific analysis. One of my key points is that the idea of drinking “as much as tolerable” did not have any science to back it when it was eagerly incorporated into the 1996 ACSM guidelines. Those guidelines were not drawn up by completely independent scientists – as also applies to the 2007 guidelines. Waterlogged asks the question: Who benefitted from these 1996 guidelines since certainly the athletes did not? Is that a “conspiracy”? I don’t know but I don’t think I ever used that term. I have always just asked the question of how did such non-science become incorporated into drinking advice that would have to become the global standard because of the international standing of the ACSM as THE credible source of information. Why was not more care taken before coming to that advice? Was this the result of a “conspiracy”? I do not know but it was certainly a very bad misuse of science.

    You have also not analyzed the role of the Gatorade Sports Science Institute in promoting the idea that unless you drink at least 40 ounces of fluid per hour (1.2L/hr) during exercise “your performance will suffer”, based on the 1996 ACSM guidelines. Check also the article of my student Fernando Beltrami who analyzed the drinking advice on the different Gatorade websites globally and whether those were all “evidence-based”. Has that advice been changed as a result of that article?

    Also note that by 1998 the US Military had realized the catastrophic effects of this advice to drink ahead of thirst and so they revised their guidelines and began to preach limits to fluid consumption. Yet faced with the same evidence the ACSM took 11 years to change its guidelines and then it still got it wrong. Why the delay? Much damage happened in the interim. Is this evidence for a “conspiracy”? I do not know but it is certainly not something of which the ACSM and its advisors can be proud. Hopefully they will still correct that in future.

    Please note that Waterlogged only includes 60% of what I actually submitted for publication. The editors said there was enough evidence there to make my argument in a way that was incontestable and I did not need to include everything that there is. So there is more evidence especially for industry involvement than that presented in Waterlogged. The BMJ article presents additional evidence for this.

    FInally the influence of industry in still getting the wrong message out can be found today on the Ironman website

    http://ironman.com/training/gu-fuels-u-hyponatremia-and-the-endurance-athlete?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+ironman%2Ftopstories+%28Ironman.com+Top+Stories%29&utm_content=Google+Reader#axzz24qnlUoFM

    This article promoted by industry says that athletes in the Ironman need to drink ahead of thirst and to ingest added sodium to prevent hyponatremia. Both pieces of advice are simply wrong and without any basis in science. Interestingly Waterlogged shows that the Hawaiian Ironman is the single sporting event with the highest recorded incidence of exercise-associated hyponatremia in any event in the world. This “new” industry-directed advice will not help change that unenviable status.

    Incidentally the word “conspiracy” does not appear in the index of Waterlogged. Perhaps you can find the word somewhere in the text? Or elsewhere in my writings?

  6. August 29, 2012 12:57 pm

    Nice commentary! I shared it with the ISSN Facebook Group! https://www.facebook.com/groups/TheISSN/

  7. July 7, 2013 11:50 am

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