Electrolyte powders

Story

Connected to · 2

cofactor · 1

Recovery science
Sweat is more than 99% water, and a liter of sweat carries off about 1 g of sodium, far less than an ordinary diet supplies, so plain water is enough for a session of an hour or less. Electrolytes are needed only for long, heavy sweating, exercise in the heat, or people with especially salty sweat. Exercise-associated hyponatremia is a real risk, driven mainly by drinking more than you sweat: if a headache keeps getting worse, or vomiting or confusion sets in after drinking a lot of plain water during long exercise, seek emergency care right away.

contrast · 1

First half or full
In a long race, drinking more than you lose is more dangerous than running short of salt: it dilutes the sodium in your blood, which is exercise-associated hyponatremia. Sports drinks are hypotonic too, so drinking too much of them is not protective, and when fluid intake is excessive, extra salt cannot prevent it. At the finish of the 2002 Boston Marathon, 13% of runners had hyponatremia, linked to weight gain during the race and finishing in more than 4 hours.

Read full story

Stop 1/5

What's actually in sweat

EVIDENCEGUIDE 2

READ THE ORIGINAL

Of everything sweat carries out of the body, only one thing really matters: salt, or more precisely the sodium in salt. Potassium, calcium and magnesium leave in sweat too, but in amounts small enough to ignore. So when you decide whether to replace electrolytes, look at one thing first: how much sodium this bout of sweating cost you, and how much your meals and drinks put back.

In easy-to-remember terms: an hour of heavy sweating (about 1 L of sweat) loses roughly 900 mg of sodium, the amount in 2.3 g of salt. It also takes about 200 mg of potassium, 5 mg of magnesium and 40 mg of calcium, and those last few are too small to worry about.

How salty sweat is varies from person to person. Someone whose clothes show white salt marks and whose skin tastes salty after training can lose several times as much sodium in the same hour of exercise as someone who leaves almost no marks. Genes and heat acclimation decide it together: after ten days or so of training in the heat, the body learns to hold on to salt and sweat becomes less salty.

The danger in the other direction matters more. If you keep drinking large amounts of water during long exercise, the sodium in your blood gets diluted. A headache, nausea or confusion during or after exercise, when you have been drinking all along, may be low blood sodium from drinking too much, called exercise-associated hyponatremia (EAH): this is an emergency; stop drinking water and call emergency services now.

Watch this step as a mechanism animationOpen mechanism

Educational content, not medical advice. See a clinician about your own case.

Back

Electrolyte powders

Story

Connected to · 2

cofactor · 1

Recovery science
Sweat is more than 99% water, and a liter of sweat carries off about 1 g of sodium, far less than an ordinary diet supplies, so plain water is enough for a session of an hour or less. Electrolytes are needed only for long, heavy sweating, exercise in the heat, or people with especially salty sweat. Exercise-associated hyponatremia is a real risk, driven mainly by drinking more than you sweat: if a headache keeps getting worse, or vomiting or confusion sets in after drinking a lot of plain water during long exercise, seek emergency care right away.

contrast · 1

First half or full
In a long race, drinking more than you lose is more dangerous than running short of salt: it dilutes the sodium in your blood, which is exercise-associated hyponatremia. Sports drinks are hypotonic too, so drinking too much of them is not protective, and when fluid intake is excessive, extra salt cannot prevent it. At the finish of the 2002 Boston Marathon, 13% of runners had hyponatremia, linked to weight gain during the race and finishing in more than 4 hours.

Read full story

Stop 1/5

What's actually in sweat

EVIDENCEGUIDE 2

READ THE ORIGINAL

Of everything sweat carries out of the body, only one thing really matters: salt, or more precisely the sodium in salt. Potassium, calcium and magnesium leave in sweat too, but in amounts small enough to ignore. So when you decide whether to replace electrolytes, look at one thing first: how much sodium this bout of sweating cost you, and how much your meals and drinks put back.

In easy-to-remember terms: an hour of heavy sweating (about 1 L of sweat) loses roughly 900 mg of sodium, the amount in 2.3 g of salt. It also takes about 200 mg of potassium, 5 mg of magnesium and 40 mg of calcium, and those last few are too small to worry about.

How salty sweat is varies from person to person. Someone whose clothes show white salt marks and whose skin tastes salty after training can lose several times as much sodium in the same hour of exercise as someone who leaves almost no marks. Genes and heat acclimation decide it together: after ten days or so of training in the heat, the body learns to hold on to salt and sweat becomes less salty.

The danger in the other direction matters more. If you keep drinking large amounts of water during long exercise, the sodium in your blood gets diluted. A headache, nausea or confusion during or after exercise, when you have been drinking all along, may be low blood sodium from drinking too much, called exercise-associated hyponatremia (EAH): this is an emergency; stop drinking water and call emergency services now.

Watch this step as a mechanism animationOpen mechanism

Educational content, not medical advice. See a clinician about your own case.