It's not a myth, it seems to be true. In a current study, Pickle juice had “relieved a cramp 45 percent faster” than drinking no fluids and about 37 percent faster than water. So I guess you athletes need to stock up on the stuff.
Source: http://funadvice.com/r/3k27928gda
It's full of electrolytes... athletes have used this for a long time. The downside has always been that the taste is not conducive to strenuous activity on particularly hot days when an athlete will be sweating out a lot of the salts in their bodies. This led to the creation of Gatorade... it was much easier to drink than pickle brine.
It's also good for hangovers and I have used it to prevent episodes of sleep paralysis.
With each passing day we all learn something new! :)
