You lose both water and sodium when you sweat, and both need to be replaced to avoid headaches, muscle cramps, conservatism and a myriad of other painful ailments. And proper hydration is said to be wonderful for the skin. It’s not all about ball bearings as Irwin M. Fletcher would have you believe. It’s more about electrolytes, magnesium, potassium and sodium.
I drank from a garden hose, never knowingly consumed an electrolyte, filled my glass with tap water and made it to 73. But on the downside I must confess my skin does not “Glow.” If only I had this information sooner!