In the world of endurance sports, electrolyte replacement – especially sodium – has taken on new dimensions as science advances and our understanding of athletes' real needs deepens. For a long time, the standard advice revolved around avoiding dehydration at all costs. Today, experts propose more personalized and evidence-based approaches.
The importance of sodium in endurance performance.
Sodium is one of the most critical electrolytes for endurance athletes, as it helps maintain fluid balance, neuromuscular function, and blood pressure. For the general population, the recommended daily intake is 2.3 g. However, endurance athletes frequently exceed this limit – and with good reason.
During prolonged sessions of physical exertion, especially in intense heat, sodium losses through sweat can reach levels between 3,500 and 7,000 mg per day, according to studies published in the Journal of Sports Sciences [2]. Ignoring this loss can compromise performance, lead to premature fatigue, muscle cramps, and even collapse due to dehydration.
Sports drinks and smart supplementation
For events lasting more than two hours, the use of sports drinks containing between 0.5 and 0.7 g of sodium per liter is already a well-established practice, according to the American College of Sports Medicine guidelines [1]. This strategy not only helps maintain stable electrolyte levels, but also contributes to the absorption of water and carbohydrates during exercise, thus improving performance.
However, one of the new paradigms is understanding that sodium supplementation does not need to be extreme. Recent studies, such as the one published in the British Journal of Sports Medicine [3], indicate that sodium replacement, when done properly, does not need to be excessive to avoid conditions such as hyponatremia – a condition of excessive dilution of sodium in the blood. In other words: more is not necessarily better.
Individual adjustment: the key to performance.
The big lesson from recent years is that electrolyte replacement must be personalized. Each athlete has a "sweat signature"—some lose more sodium than others, depending on factors such as genetics, heat acclimation, exercise intensity, and the type of clothing worn during sports practice.
References:
1.American College of Sports Medicine Position Stand. Nutrition and Athletic Performance.
Rodriguez NR, Di Marco NM, Langley S.
Medicine and Science in Sports and Exercise. 2009;41(3):709-31. doi:10.1249/MSS.0b013e31890eb86.
2.
Fluid and Electrolyte Needs for Training, Competition, and Recovery.
Shirreffs SM, Sawka MN.
Journal of Sports Sciences. 2011;29 Suppl 1:S39-46. doi:10.1080/02640414.2011.614269.
3.
Sodium Supplementation Is Not Required to Maintain Serum Sodium Concentrations During an Ironman Triathlon.
Hew-Butler TD, Sharwood K, Collins M, Speedy D, Noakes T.
British Journal of Sports Medicine. 2006;40(3):255-9. doi:10.1136/bjsm.2005.022418.
