The Sports Drink Debate

One the most mysterious parts to our racing...

What’s the best nutrition plan for long course racing? Answer: Drink to thirst, forget sodium, and consume multiple transportable carbs.

Paul Laursen, PhD

(If you would like to add to this subject please feel free via the comments box at the end of the article)

If you’ve been keeping up with the news lately, you may have noticed a bit of a buzz on the topic of sports drinks, and how they aren’t all they’re cracked up to be. This comes on the back of Professor Tim Noakes’ recent book on the topic, ‘Waterlogged’, along with an independent investigation by the British Medical Journal and the BBC into the claims made by the sports drink industry and the shaky science behind those claims.  What I’ll do in this article is explain to you why the issue is important to grab ahold of as an age group athlete, and finish by outlining what science says will maximise your performance in your next long course triathlon event.

Why the issue of hydration is important?

There are a couple of reasons actually.  When we talk about nutrition and endurance sport, we’re usually interested in what we should consume before, during and after our race to compete at our best and remain healthy.  The main thing we hear

One the most mysterious parts to our racing…

athletes talk about, whether it’s a fellow triathlete or an elite we all respect, is how they either did or didn’t get it right on the day because of their nutrition and hydration.  This message is widespread throughout sport today.  While fueling, in terms of not getting enough carbohydrates on board during long distance events is a possible issue (i.e., bonking – discussed later), it very rarely  stems from a lack of fluid intake.  Instead, drinking too much tends to be the real (and potentially dangerous or even lethal) issue.  So that’s why this issue is important for you to understand and even discuss with your peers.  No one has ever perished in a triathlon from dehydration, and you can in fact perform quite well in a dehydrated state (i.e., the winners, our elite athletes, typically lose the most weight during the race) – but you can die from drinking too much.

How could this happen? 

I’m speaking to you as a scientist, practitioner, and age-group athlete myself when I tell you that this can occur, and does so, during endurance and ultra-endurance events; particularly in us age-groupers.  Remember that the message to ‘hydrate’ has been around for quite a while.  It’s gospel for many coaches, athletes, and even sports medicine practitioners.  It was less than 10 years ago that I used to promote this same message to my students when I lectured on the topic.  I would tell them, wrongly, that we have to drink to prevent any body weight loss during exercise.  That we have to drink to stay ahead of thirst because we can’t trust thirst.  And that even a 2% reduction in body weight from sweating will diminish our performance (this is what the lab-based studies were showing, and the industry promoting – problem was, the science wasn’t interpreted correctly as we now know we respond quite differently in outdoor conditions).

But that incorrect message from the scientists, myself included, filtered down to the masses, through the media and the sports drink marketing campaigns.  And we age-group endurance athletes remembered that message.  So when we feel muscle soreness and fatigue during our long distance racing, it’s only natural for us to think that some of those signals could be due to nutritional issues such as dehydration. Under such situations, when fluid is available (as it always is at aid stations) – we drink.  More often than not, and especially in slower athletes, we can wind up drinking too much.  As mentioned, this can be harmful to our health.

The disease of overdrinking – hyponatremia

Hyponatremia is a result of low sodium levels in your blood stream.  The reason you get low sodium levels in your blood stream from drinking too much is due to the simple principle of dilution (more water relative to the salt that’s already there).  The confusing thing to realise, and this is where the sports drink companies really get us, is that electrolytes in sports drinks do nothing to prevent this dilution.  That’s because the salt levels in sports drinks are so low relative to its high concentration in our blood stream.  So whatever you drink, if you’re drinking too much, that is, ahead of your thirst signals, you can cause this dilutional hyponatremia to occur.  The organ this acts on is your brain; hyponatremia causes it to swell.

When hyponatremia gets bad, you experience nausea, confusion and disorientation.  You’ll often be vomiting clear liquids too. Extreme cases of hyponatremia can occur when medical practitioners unwittingly exacerbate the problem by adding an intravenous bag of saline to one’s body in the medical tent, further diluting the blood. Sadly, this occurred on a number of occasions over the past decade, prior to our clearer understanding of the issue, resulting in preventable coma and/or death.  Twelve known fatalities have occurred, and thousands of hospitalisations have been reported as a direct result of hyponatremia..  This is why I am compelled to talk about the issue– this is why I feel the sports drink companies have gone too far with their message to hydrate, hydrate, hydrate.  If the message is killing us, then clearly a pretty big line has been crossed.

What can I do about it and how can I maximise my long course performance and compete safely?

The answer really is quite easy.

  • First – just drink to thirst.  If you’re thirsty, then drink.  If you’re not thirsty, then don’t drink.  Your body’s own sophisticated, inbuilt mechanisms are there to tell you exactly how much fluid your body needs.  Just listen to it.
  • Second – forget sodium.  There’s never been a study showing a benefit of sodium supplementation to performance, and it doesn’t prevent cramping or hyponatremia.  So don’t waste your money on sodium tablets, and don’t worry about how much or little sodium is in any particular nutritional product.  It’s not going to matter.  You get all the sodium you need in your diet, and if you’re caked in sodium during your training and racing, it only means that you have possibly too much sodium in your diet, as your sweat glands only secrete sodium when there is an excess in your body – it does that to get rid of it.
  • Third – carbs are important, and are likely more important the longer your race goes on (i.e., 70.3 to Ironman).  This is because carbs support high intensity energy metabolism, and your internal (muscle and liver) glycogen levels (stored carbs) will diminish once your exercise duration extends beyond 3 hours.

A bunch of research over the last 5 years or so has shown that if you consume the carbs of glucose and fructose in about a 2:1 ratio (multiple transportable carbohydrates), you can get a bit more carb on board to benefit prolonged endurance exercise, and prevent ‘the bonk’ (many energy products with this ratio are currently on the market – just pick a few you like the taste of).  In general, you want to shoot for around 90 g of carbohydrate per hour in that 2:1 ratio, realising of course that individual differences will occur, so you might want to experiment with greater or lesser amounts for yourself..  I’ve found that 90 g/h is right on the money for me.  Remember that that carb could come from a banana, a gel, or even, a sports drink!  Just work it out so that each hour you’re getting about 90 g in that 2:1 ratio of glucose:fructose (details on my site).  Last but not least – train well (volume is key) and pace appropriately on race day (i.e., at paces you know you can handle from your training).

If you’re like me and you like to play around with numbers and want your info in the palm of your hand, these guidelines and a calculator are available in an app version for iPhone and iPad from the iTunes store.

Train well, listen to your body, and drink to thirst!


About the author

Paul Laursen is the lead Performance Physiologist for High Performance Sport New Zealand, and is an Adjunct Professor of exercise physiology from AUT University, Auckland.  He completed his PhD from the University of Queensland in 2004, and has done a number of research studies examining the relationship between hydration status, body temperature and endurance performance. His hobby is triathlon and he’s completed 14 Ironman events worldwide.


The views in this article are those of the author. Trizone recommends that you seek your own professional advise specific to your body and needs before adopting a race nutrition plan.



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  • Dr Nicole Anderson

    Finally finally finally! Im so relieved to read this article on a public website! Thank you Mr Laursen for providing this potentially life saving advice to a group who are heavilly influenced by pseudoscientific marketing slogans which are inherently dangerous. Very greatful to finally see that someone who understands not just excercise physiology but excercise pathophysiology and is brave enough to challenge the establishment. Well done!

    • Thanks for your kind comments Dr Anderson. Commendation should also go out to Trizone for their willingness to publish the story. Nice to see an editor that cares about the health of his readership.

  • Troy Dwyer

    Paul, I’ve been told that water with sodium actually helps the digestion process and allows carbs to be absorbed by the body quicker during an event like Ironman. What are your thoughts on this?

    • Hi Troy. That’s a great question. That’s what I used to think too. But the fact of the matter is, any sodium co-ingested with carbohydrate has a negligible influence on fluid or carbohydrate absorption. I’ve found three studies showing no effect (Gisolfi et al., 1995; 1998; Jeukendrup et al., 2009). The reason for this is because sodium, in just the right amount, is always added by your pancreas via the pancreatic duct to whatever contents are being emptied from your stomach to your small intestine (site of absorption). So once again, our smart body figures out exactly what it needs to do to keep things running efficiently. Carbs are vital during Ironman, but again, no evidence that sodium does anything very special. Unfortunately, just another myth. From a personal standpoint, I’ve raced using sodium supplementation in the past, but more recently without. I would say my gut has felt much better without. Suggest giving it a try.

      Gisolfi CV, Summers RD, Schedl HP, Bleiler TL. Effect of sodium concentration in a carbohydrate-electrolyte solution on intestinal absorption. Med Sci Sports Exerc. 1995 Oct;27(10):1414-20.

      Gisolfi CV, Summers RW, Lambert GP, Xia T. Effect of beverage osmolality on intestinal fluid absorption during exercise. J Appl Physiol. 1998 Nov;85(5):1941-8.

      Jeukendrup AE, Currell K, Clarke J, Cole J, Blannin AK. Effect of beverage glucose and sodium content on fluid delivery. Nutr Metab (Lond). 2009 Feb 20;6:9.

  • Great article – I’ve heard Tim Noakes on this subject at several conferences!!

    Just in response to Troy’s comment, we advocate sodium loading pre-endurance exercise in the heat, which without fail athletes have said is a ‘miracle’ drink, allowing them to perform with out suffering the usual effects of dehydration etc when racing in hot conditions.

    I think this is coming from a slightly different angle to Troy’s comment (ie sodium loading for increasing plasma volume as opposed to for helping digestion/carb absorption), but just interesting to hear you say sodium supplementation doesn’t do anything special Paul (I’m guessing you mean during a race as opposed to loading before though).

    Here’s the first study we found on this subject:

    SIMS, S. T., L. van VLIET, J. D. COTTER, and N. J. REHRER. Sodium Loading Aids Fluid Balance and Reduces Physiological Strain of Trained Men Exercising in the Heat. Med. Sci. Sports Exerc., Vol. 39, No. 1, pp. 123–130, 2007.

    • Thanks for your kind comments Rhona. Indeed, Tim has lead the way here and I am merely helping spread the word. The issues mentioned in the article are particularly important to us long course athletes that can be out on the course for prolonged durations, with sometimes almost too many opportunities to drink.

      Your comments around pre-exercise sodium loading are interesting. I am very aware of Stacey Sims’ work from Jim Cotter’s lab in Otago. There are limitations to this study’s findings and how it relates to athletes competing in hot conditions in the field. First, the air speed in their heat chamber used was 1.5 m/s, which equals to 5.4 km/h, and is less than half the speed you’d think that well trained runners would run at when going at 70% of VO2max in the heat. I couldn’t find the speed reported in the paper, but I’m guessing they’d be running at around 12-14 km/h on the treadmill based on their VO2max. What this means is that heat storage will build up faster, and you’ll fatigue quicker in their situation. This biases a bit the nice effect of the performance improvement shown when equating it to what you’d find in the field in your athletes. Further, and the author’s acknowledge this, athletes weren’t allowed to drink anything during exercise. While the high sodium cocktail undoubtedly expanded plasma volume, which lowered osmolality and improved run time to exhaustion in the heat when athletes couldn’t drink, it’s hard to say what would happen to performance if fluid had been provided during exercise. Current opinion, and unpublished data from my lab, is that if you control thirst, performance will be optimized (i.e., the same irrespective of your plasma volume level). This is because it is the brain that determines performance. And if your brain is no longer hearing that you’re thirsty, then why would it inhibit your performance? This is why I don’t really think it matters.

      So to answer your question, I think if you’re using a nutritional intervention in your practice that your athletes ‘believe’ will work, and they ‘perceive’ a benefit from, then I’d recommend continuing to use it. However, based on my understanding, it’s not a practice I’d currently recommend to my athletes.