[A] The following conclusions are supported by good evidence:
Sweat rates and sweat sodium concentrations are highly variable between and within individuals. Athletes losing copious amounts of water and electrolytes may have higher water and electrolyte needs than the general population.
[B] The following conclusions are supported by fair evidence:
Sodium should be ingested during exercise, especially by those athletes with high sweat rates (such as >1.2 L/h), with salty sweat, or when