Thursday, June 19, 2014

The Electrolyte Myth

As the Old Man Winter finally settles into its long solstice slumber, and the temperature and humidity have begun to rise, I've already started to hear runners and cyclist talking about how many electrolytes they need to consume per hour in order to not only prevent cramping, but to continue exercising at a high level of performance.

However, as is so often the case, it appears the belief that endurance athletes need to replenish electrolytes is a bit exaggerated.

Electrolytes are sodium ions and they make up the bulk of the “salty” non-water part of your sweat. Potassium is also excreted in sweat, but electrolytes are lost 10 times faster than potassium.

While electrolytes are lost when you sweat, sweating actually increases the concentration of electrolytes in your body. This is because when you sweat, you are excreting more water than electrolytes. Just as you don’t loose potassium and electrolytes at the same rate, you don’t loose water and electrolytes at the same rate. The result is, as you become dehydrated – meaning you have less water in your blood – the sodium to water ratio also changes, causing a higher concentration of sodium.

In fact, some research shows that even after exhaustive exercise, the amount of sodium lost is quite small. This was supported by double blind placebo test, which demonstrated that people who consume sodium-free (electrolyte-free) sports drinks performed at the same levels as those who received sports drinks with added sodium.

Furthermore, there is evidence that even electrolyte-added sports drinks cannot prevent a drop in blood sodium levels, because the drinks hydrate you more than they replace electrolytes. Again changing the sodium - water ratio in your body.

However, that doesn’t mean that sports drinks are completely worthless. Drinks like Gatorade have the simple sugars needed to help replenish the carbohydrates burned by the body during long periods of exercise as well as the water needed to help stave off dehydration. In a study performed at the University of Texas in Austin, they found that male athletes experienced a 6 percent improvement in sprinting (on a bike) when they consumed enough water to remain properly hydrated when compared to a group which drank water, but didn’t consume enough water to stave off  dehydration. This shouldn't be all that surprising... dehydration hurts performance. 

The final word: adding electrolytes does not appear to be needed, especially for performances that are less than 2 hours in duration. However learning to properly fuel your body is still an important and necessary skill, particularly when exercising in the heat. Experiment and find out what works for you. Even if the research doesn't support it, placebos can have a strong performance enhancing ability. Now go get outside!  

Brazier, Brendan, Thrive Fitness; The Vegan-Based Training Program for Maximum Strength, Health, and Fitness. Da Capo Press, 2009.

Burke, L. M.; et al., “Carbohydrates for training and competition.” Journal of Sports Sciences 2011, 29 (sup1), S17-S27.

Coyle, E. F., “Fluid and fuel intake during exercise.” Journal of Sports Sciences 2004, 22 (1), 39-55.

Gisolfi, C.; et. al. “Intestinal fluid absorption during exercise: role of sport drink osmolality and [Na+].” Medicine & Science in Sports & Exercise 2001, 33 (6), 907-915.

Larson-Meyer, D. Enette, Vegetarian Sports Nutrition: Food Choices and Eating Plans for Fitness and Performance. Human Kinetics, 2007.

(Note Runner'sConnect also has an article on electrolyte consumption, and they were kind enough to point me to some of the articles they consulted.) 

As always the information presented in this blog is for educational purposes only. It should not be considered as specific medical, nutritional, lifestyle, or other health-related advice.

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