I recently became aware of several athletes consuming salt tablets during Ironman events to replace sodium lost by sweating during exercise. It has always been my understanding that actual oral salt supplementation was an archaic regime that was discontinued many years ago, and came from the early days of marathon and ultra-marathon running. This prompted me into doing research into the current and up to date scientific position on sodium supplementation during ultra racing.
The major problem in finding a definitive conclusion is that there is so much conflicting information. Therefore, I focussed on athletic journals, creditable medical articles and scientific research, ignoring anecdotes from unqualified sources.
One of the common myths is that cramping is caused by sodium depletion. Training Peaks published an article “The Straight Dope on Salt”. A 2005 study found no difference in blood sodium levels between athletes who suffered muscle cramps and athletes who did not during an Ironman triathlon. Some exercise physiologists now believe that exercise-induced muscle cramps represent a type of tendon fatigue that occurs during unaccustomed levels of exertion. The fact that some athletes are especially prone to muscle cramps while others are not also suggesting that sodium depletion is not the cause. (Pacific Health Laboratories, 2009). This is also supported by (Noakes, 1985) who suggests that “muscle cramps developed during prolonged exercise are almost certainly not due to salt depletion and should not respond dramatically to salt ingestion.”
According to (Pacific Health Laboratories, 2009), studies from the University of Cape Town, South Africa, and the University of Auckland, New Zealand, found that sodium supplementation during an Ironman triathlon had no effect on blood sodium concentration or blood plasma volume. This statement coupled with the fact that “there is surprisingly little scientific evidence that salt consumption during exercise provides any benefit” is contrary to the notion held by athletes who commonly use oral salt supplementation.
Furthermore, the author of this article also identified links between salt consumption and hyponatremia. Hyponatremia is also known as water intoxication which is characterized by low salt concentration in the blood. It could be assumed that salt consumption may counteract the potential of hyponatremia but this is not the case. According to Fitzgerald (2016) “The best way to avoid hyponatremia is not to consume more salt, but to drink less fluid instead.”
So is there a need to supplement with additional salt orally? Fitzgerald states that “evidence clearly demonstrates that a typical sports drink provides enough salt to optimize performance and protect the athlete's health, provided he or she doesn't overdrink. There's no measurable benefit associated with consuming extra salt.” Additionally, according to (Tucker, 2016), “Sweating causes some sodium loss, but because the sodium content of sweat is so low relative to body fluids, your sodium concentration will rise. And it is the concentration that is important, since this controls fluid shifts in the body. It is NOT possible, even for a “salty sweater”, to LOSE sodium through sweat.” Tucker is also very clear in stating that one should not “waste money on salt tablets – you don’t need them!”
What isn’t in dispute is the fact that athletes need to replace electrolytes when participating in events longer than 2 hours. The electrolytes sodium and potassium play a critical role in regulating your body’s water balance during exercise: the levels of these electrolytes allow your muscle cells (and every other cell in your body, for that matter) to retain the right amount of water (Davis, 2015). Future articles will discuss optimal electrolyte intake along with race nutrition.
This article has referenced qualified sources:
Ross Tucker is Professor of Exercise Physiology with the School of Medicine of the University of the Free State. He is the scientific and research consultant to World Rugby, ambassador and scientific advisor to Virgin Active and adidas. In the past, he has consulted with a number of teams in high performance sport, including SA Sevens (including the 2009/2010 World Series winning team), SA Kayaking, SA Triathlon, USA triathlon and the UK Olympic Committee.
Timothy David Noakes (born 1949) is a South African scientist, and an emeritus professor in the Division of Exercise Science and Sports Medicine at the University of Cape Town. He is also a member of the National Research Foundation of South Africa, who list him as one of their highest-rated members. He has run more than 70 marathons and ultramarathons, and is the author of several books on exercise and diet.
Matt Fitzgerald is a certified sports nutritionist, Matt has served as a consultant to numerous sports nutrition companies, including Energy First, Healthy Directions, PacificHealth Labs, and Next Proteins. Having coached for Carmichael Training Systems in the early 2000’s, Matt continues to design readymade training plans for triathletes and runners that are sold through TrainingPeaks.com