Sodium and electrolytes A
For exercise longer than 2 hours, sodium with water protects against hyponatremia
Citable fact
«Sodium and electrolytes» — evidence level A. Dosage: A guideline is 300-700 mg of sodium per liter of fluid drunk; with heavy sweating and exercise longer than 2-3 hours, up to 1000 mg/l. The upper level of 2300 mg per day refers to the chronic diet, not to exercise. A hypertonic solution for symptoms of hyponatremia is given only as prescribed by a physician. Source: PMID 25551404, permanent link to the source in the list below.
How it works
Sodium is the main extracellular cation: it retains plasma volume and maintains osmolality and the sense of thirst. About 500-1500 mg of sodium per liter is lost in sweat, and replacing it with water alone leads to hyponatremia.
Dosage and intake
A guideline is 300-700 mg of sodium per liter of fluid drunk; with heavy sweating and exercise longer than 2-3 hours, up to 1000 mg/l. The upper level of 2300 mg per day refers to the chronic diet, not to exercise. A hypertonic solution for symptoms of hyponatremia is given only as prescribed by a physician.
300-500 ml 2 hours before the start, then in divided doses every 15-20 minutes during exercise, and replenishment after the finish taking into account the change in body weight.
Forms
Sodium drinks, electrolyte capsules and tablets, and saline solutions have been studied. A 3% hypertonic solution is used only by medical personnel.
What is confirmed
- Prevents hyponatremia during exercise longer than 2-3 hours
- Improves the taste of the drink and stimulates voluntary drinking
- Supports plasma volume and performance in the heat
Adverse effects and limitations
- Excess water without sodium is more dangerous than a shortage: hyponatremia can lead to cerebral edema and death
- Salt tablets without water increase dehydration and irritate the stomach
- In hypertension, kidney and heart disease, high sodium intake requires agreement with a physician
- Symptoms of hyponatremia - nausea, confusion, headache - are a reason to stop exercise and seek help
Interactions
- Thiazide diuretics increase the risk of hyponatremia
- NSAIDs and SSRIs are also associated with hyponatremia
Who must not use it
- Under 18 years: Electrolyte drinks for young athletes are acceptable during prolonged exercise; excess sodium is not needed.
- Pregnancy and lactation: The fluid requirement is higher; sodium supplements - in agreement with a physician.
- hypertension
- chronic kidney disease
- heart failure
- taking diuretics or SSRIs
Sources
- Sodium Supplementation and Exercise-Associated Hyponatremia during Prolonged Exercise · Hoffman MD, Stuempfle KJ · Medicine and science in sports and exercise, 2015 · PMID 25551404
- American College of Sports Medicine position stand. Exercise and fluid replacement · American College of Sports Medicine, Sawka MN, Burke LM · Medicine and science in sports and exercise, 2007 · PMID 17277604
- Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance · Thomas DT, Erdman KA, Burke LM · Journal of the Academy of Nutrition and Dietetics, 2016 · PMID 26920240
See also
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