Other than the 5/28 of days I deal with women, my only bad experience with cramping was in November 2006 when I did Cheops Pyramid
in Grand Canyon.
The main difference between this and the many other Grand Canyon hikes I have done is that I forgot (!!!) to bring Gatorade powder on the hike, and I wound up drinking water all day. Sure, salty foods are a fine source of electrolytes, but I didn't make a special point to bring salty foods because I always get plenty of electrolytes from the Gatorade that I would normally bring on such a hike. So I just had water and a bunch of sweet crap to eat all day.
As opposed to a summer hike above 12000 feet, where it is maybe 55F on a warm day, a summer hike through Grand Canyon means you will sweat a lot, since it is 100 to 110F at the bottom during the day. On a 25-mile (12-hour) trans-canyon hike in summer
, I consistently drink about 2.5 gallons, of which maybe 2 gallons are Gatorade and 1/2 gallon is plain water. (The amount consumed would be a lot more than that, if not for part of the trail being at higher elevation.)
So on this Cheops hike, I forgot to bring Gatorade, and I hiked with just water anyway, unconcerned, possibly because it was November and not summer. On the way up, about half-way to the rim, I began to have serious cramping in my thighs on every step. I don't recall it to be a life-threatening situation, but I do remember that it was pretty intense, and it seriously affected my uphill performance. I also remember wishing I could just get some salty food or Gatorade from somebody somewhere.
In the summer, it would have been much more serious. I would have lost a lot more electrolytes and drank a lot more water. I'm sure more than one person has died of hyponatremia on long desert hikes, particularly on hot canyon hikes, where you have to hike uphill to finish (get out).
For the cramping, I am convinced that my situation was due to the lack of electrolytes. While it doesn't qualify as a scientific experiment, it is the only time in my life that I ever had cramping problems in my legs in all the hikes I have been on, including the 46 Grand Canyon long dayhikes I have done.