Exciting news for endurance athletes has just been published which can have an impact on your training and performance times. Researchers from Madrid, Spain have shown that an electrolyte replacement tablet can improve performance in a randomized controlled trial of half-ironman participants.[i] The endurance athletes who took the electrolyte supplement averaged 26 minutes less than the equally matched controls who took a placebo tablet (307 minutes vs 333 for placebo). Notably, the running and cycling speeds improved. This indicates that the differences in the two groups’ performance became evident after the first leg.
In addition to sodium, the electrolyte tablets contained chloride, potassium, and magnesium, and were given three times during the race. All athletes drank their usual hydration beverages ad libitum – according to thirst – and those who took the electrolyte supplement consumed 27% more fluid volume than controls (1.9L vs. 1.5L), presumably as a result of the salt-stimulated thirst. The author notes “This positive effect on performance relates to an increase in the concentration of electrolytes in the blood, making them drink more fluids during the race, and improves the water and electrolyte balances during the competition”.
For the first time, a controlled field study of electrolyte tablet supplementation with ad libitum fluid consumption rather than forced fluid/electrolyte ratios, has been shown to improve performance in an endurance event. This suggests that increasing electrolyte intake to more closely replace losses from sweating, separately from fluid intake, may be a useful strategy in endurance athletics. A further benefit would be to reduce the serious risk from hyponatremia – low plasma sodium levels – which can occur from consuming too much fluid that is low or absent in sodium.
Do I need to take the electrolyte during the race?
Probably not! The electrolyte supplement used in this study was an immediate release tablet. Endurance athletes by now should be aware that electrolyte replacement can achieved with a sustained release tablet. REPLACE SR is designed to release continually over 4-6 hours. For most individuals and events, this means a single dose (1-3 electrolyte tablets) can be taken prior to the race. From then on, just follow your thirst. Whether you choose to drink water or a sports beverage, taking the extra electrolytes will result in additional fluid consumption and better fluid/electrolyte balance, according to these authors.
Study link: http://www.ncbi.nlm.nih.gov/pubmed/25683094
[i] Del Coso, J. et al. Effects of oral salt supplementation on physical performance during a half-ironman: A randomized controlled trial. Scand J Med Sci Sports 2015: doi:10.111/sms.12427
Keywords: electrolyte balance, hydration, sodium, hyponatremia, endurance exercise.