No, the sugar in the soda didn't cause leg cramps. And
arugula has very little sugar in the plant. It's a member of the Brassicaceae family and is related, as are many vegetables, to cabbages which aren't known to have lots of sugars in them. Hint: If it tastes sweet, it has sugar. If it doesn't, well, it doesn't.
Nor does the soda have much in way of "salts" in it. It has some sodium salts of various types but the total sodium concentration is about 4% which isn't that high.
The
WebMD page on nighttime leg cramps list 3 causes that are related to NYMXer's issue
His other mistake was to start out on an empty tank.
This website is prehaps a bit more on target than the WebMD page when it comes to exercise induced cramps. This is the most important quote from that website
Starting exercise without energy on board in the morning puts the body in a glycogen deficient. The body will attempt to adjust by drawing on other energy stores but it takes time to mobilize those. Meanwhile, you are exercising and losing fluids as well as electrolytes which will also contribute to cramping. By the time NYMXer got something to eat, he was already in a hole and his food and soda didn't lift him out of the hole much. Add in summer heat and humidity and the hole is just deeper.
Basically, eat something before you start riding. Eat something and/or drink while riding. Gatorade does do a great job of replenishing sugar and electrolytes while riding but water is just as important.
I fully understand where NYMXer is coming from. I've experience cramps during a ride and post ride. I often get them while on tour because I haven't been drinking and eating enough while also doing a lot of intense climbing. The worst are quad cramps. It feels like your leg is going to pull your femur into pieces. The worst time to get a quad cramp is when you are crawling into a tent and you are stuck with your body half way in and your legs rigid because it hurts so much. And you can't go and get the Gatorade you need because your legs simply won't work to get you up off the ground.