True story:
A few years ago I was riding a 50 mile fun mountain bike ride, and at the first feed station they had little bottles of pickle juice. I asked what that was all about, and they said it helped for cramps.
"Don't take it before you cramp," they said. "Wait until you do cramp, then drink it."
Bizarre, I though, but I grabbed a couple of little bottles anyway, just because.
At about mile 30 I came upon a guy who was obviously was in pain. standing next to his bike, his legs locked up.
I told him what they'd said about pickle juice and gave him one of the bottles, telling him I had no experience with the stuff, but give it a try.
He drank the pickle juice and almost immediately said, "Wow! That's amazing!" and jumped on his bike and rode away.
ABout ten miles later I came across another guy with severe cramps, and I told him about the first dude and gave him my second bottle. He drank it, and just like the first guy, IMMEDIATELY felt better and was able to ride.
Blown away by the speed with which it worked for these two riders, I did some digging, and it turns out the prevailing theory is that it's neurological- it acts on the system that contracts and releases muscles, not on the actual muscles themselves.
So, in other words, it's psychosomatic. But it absolutely works.