Re: The truth about sports drinks
19 August 2012
To the Editor:
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.
Interestingly all 4 papers are of more than passing interest to the sports drink industry since they show that overdrinking of fluid alone causes exercise-associated hyponatraemia; that evidence for the benefits of sports drinks will be inflated by studies conducted in laboratories in which there is inadequate convective cooling; and that high levels of dehydration are found in the fastest finishers in two Ironman triathlons. In fact there was an inverse relationship between finishing time and the extent of weight loss in those two Ironman races so that more weight loss was associated with faster finishing times. The reviews of these rejected papers were generally antagonistic and dismissive, in line with the opinion expressed by the then head of the Gatorade Sports Science Institute5-7.
Of particular interest was a study8 in which we re-analyzed data from an industry-funded study. After review by 3 referees we were informed that the letter reporting our finding could not be published in the Journal of Applied Physiology since it was of poor science causing us to “misinterpret” the data. Perhaps the fact that our re-analysis found, inconveniently for the industry since it conflicts with years of their targeted messaging, that water not sodium balance determines the blood sodium concentration response to prolonged exercise, explains why this letter could not be published?
That study confirmed what we have been arguing since 1985 and which if enacted then would have saved lives and prevented the global spread of exercise-associated hyponatraemia.
1. Speedy DB, Rogers IR, Noakes TD, Wright S, Thompson JM, Campbell R, et al. Exercise-induced hyponatremia in ultradistance triathletes is caused by inappropriate fluid retention. Clin J Sport Med 2000;10:272-78.
2. Sharwood K, Collins M, Goedecke J, Wilson G, Noakes TD. Weight changes, sodium levels, and performance in the South African Ironman Triathlon. Clin J Sport Med 2002;12:391-99.
3. Sharwood KA, Collins M, Goedecke JH, Wilson G, Noakes TD. Weight changes, medical complications, and performance during an Ironman triathlon. Br J Sports Med 2004;38:718-24.
4. Saunders AG, Dugas JP, Tucker R, Lambert MI, Noakes TD. The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environment. Acta Physiol.Scand. 2005;183:241-55.
5. Murray B. Manufactured arguments: turning consensus into controversy does not advance science. Br J Sports Med 2007;41:106-07.
6. Noakes TD, Speedy DB. Case proven: exercise associated hyponatraemia is due to overdrinking. So why did it take 20 years before the original evidence was accepted? Br J Sports Med 2006;40:567-72.
7. Noakes TD, Speedy DB. Lobbyists for the sports drink industry: an example of the rise of "contrarianism" in modern scientific debate. Br J Sports Med 2007;41:107-09.
8. Noakes TD. Changes in body mass alone explain almost all of the variance in the serum sodium concentrations during prolonged exercise. Has commercial influence impeded scientific endeavour? Br J Sports Med 2011;45:475-77.
Competing interests: Fully disclosed in a previous rapid response; to the BMJ in a related article published in this series and in Waterlogged on page x.
University of Cape Town, Sports Science Institute of South Africa, Boundary Road, Newlands, 7700, South Africa
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