Originally Posted by ollinger
People forget (or never knew) that sweat is hypoosmolar to plasma with regard to "salt" (sodium and chloride), i.e. what you sweat out has less salt in it than your blood plasma. This means the amount of salt you need to consume during a match is very low, really negligible. I'd be concerned about consuming very saline liquids like pickle juice as there's a risk of raising your BP with too much salt, potentially dangerous during physical activity that raises your BP in any event.
Unfortunately, this isn't that relevant. In a tennis match outdoors, you can easily sweat out your entire daily requirement of sodium. This is especially true if you sweat heavily. If you do, then you really need that salt to stay properly hydrated. While salt tabs may not be the ideal solution, taking salts (not just sodium) is vital for those who cramp easily.