GSSI’s Point of View
Of all the electrolytes lost in sweat, sodium is lost in the greatest amount and is the key electrolyte to replace during and after activity, particularly when exercising in the heat. Sodium helps encourage drinking and enables the body to maintain fluid balance. Complete sodium replacement is necessary to successfully rehydrate after exercise.
During exercise, athletes and active people who sweat on a regular basis should consume a sports drink that contains enough sodium to aid hydration. The American College of Sports Medicine (ACSM) recommends that athletes consume a sports drink with at least 110 mg of sodium per 8 oz. This amount is considered "low sodium" by FDA standards. It is important to keep in mind that the public health recommendation to decrease dietary sodium intake is predominantly aimed at the elderly and individuals with a history of hypertension. Athletes and active people need not be as concerned.
Some beverages touted for their electrolyte content don't even include sodium -- the most important electrolyte for athletes and active people -- or fail to provide the minimal amount of sodium required to enhance hydration. Athletes should also be wary of products that contain only electrolytes (in isolation), as fluid and carbohydrates are also essential for optimizing athletic performance - water, carbohydrates, and electrolytes work together to keep the body hydrated and fueled during exercise.
Part 1 – Sodium Balance
• Sodium is the most important electrolyte lost in sweat and athletes need to be mindful of replacing those losses in order to increase hydration and perform at their best
• Sodium balance refers to the relationship between sodium ingested through diet and the sodium athletes lose in sweat
• Acclimation to the heat can lower an athlete’s sweat-sodium concentration, but will increase sweat rate during the process
Part 2 – Sodium and Exercise
• Sweat sodium concentration is determined by genetics, but influenced by training, acclimation, diet, and hydration status
• Sodium intake during exercise helps athletes better retain the fluids they drink and also helps reduce the physiological strain on the body by helping maintain blood volume and reducing the risk of severe muscle cramps
• Thirst is not be the best indicator of dehydration because thirst does not occur until dehydration is already present
Part 3 – Sodium Related Challenges
• Educating athletes about the benefits of sodium can be the best defense against conditions like muscle cramping and hyponatremia
• While it’s vital for athletes to avoid overdrinking to prevent hyponatremia, it’s also important for athletes to drink enough to avoid dehydration
• Athletes with high sweat-sodium concentrations can be at risk for severe muscle cramps, so replacing sodium, more than any other electrolyte, can help reduce that risk
• Plain water isn’t enough to completely rehydrate athletes; sodium is a requirement for complete rehydration