From Fellrnr.com, Running tips
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==Sodium Loss Table==
| align="center" style="background:#f0f0f0;"|'''Source'''
|Sweat of un-acclimated, unfit||80||1.8||0.9||2.2
|Sweat of un-acclimated, fit||60||1.4||0.7||1.7
The concentration of sodium in sweat depends on the sweat rate. This is believed to be because the sweat is released with a high sodium concentration, then the sodium is reabsorbed before it reaches the surface. The faster the sweating, the less chance for reabsorption.
[[File:Sweat Rate Sodium Concentration.jpg|none|thumb|300px|Sweat rate and sodium concentration<ref name="sweatrate"/>.]]
Below are some sample sources of Sodium, with the concentrations defined.
See also [[Comparison of Gels]].
Here are some hypothetical examples
* For the next run, Charlie changes his drink to add 1/4 teaspoon of extra salt to his Gatorade. He sweats and drinks the same amounts as the previous run. This time, his drink provides him with 4.7 grams of salt, or 3/4 teaspoon of salt.
Sodium Loss While Running=
Sweat rates in male runners have been measured in the range from 0.75-2.23 in winter to 0.99-2.55 in the summer (Liters per hour)<ref name="acsm"/>. At the low end, we can imagine a fit runner finishing a 3-hour marathon in winter and sweating only 2.25 Liters. Assuming they are also heat acclimated, they would only lose 2 grams of sodium, which is 5 grams of salt, less than a teaspoon. On the other end of the scale, a fit, but unacclimatized runner completing a 5 hour marathon in summer would sweat out nearly 13 Liters, 18 grams of sodium, which is 45 grams of salt or more than 7 teaspoons.