I use a vibration training machine everyday and have no problems with cramps. I originally bought one because I have very bad knee joints that would swell up badly every day. My knees are much better now and I have no swelling at all. Have also increased my lean muscle mass by 20% since using the machine. This is the company that I bought mine from: http://www.vibrationmachine.biz/
I'm sure that there are USA companies that sell these.