According to Rahel of Elms in the Yard there is a Salt Room in Israel which is fantastic for asthma sufferers. Which might explain why I had trouble climbing Masada (stupid asthma), but very little doing any other athletic activity the next day, post Dead Sea immersion.
Maybe the Ahava factory tour (which is super-ridiculous) had something to the claim that "one of the greatest mysteries of the Universe is why the Dead Sea has magical healing powers." Or something like that. I just remember that the phrase was ridiculous.