Has anyone any advice or experience with the "vibration machines" that i see in many gyms now. I am using them for warm up and for "pumping" the muscle group full of blood before exercising. (The machines i mean are like vibration plates you stand on, like 'vibro-gym', 'powerplates', 'NEMES' etc...) Comments? experiences? any good? waste of time? and if you use them, how? Thanks, cu