I have gotten shocked on side rails before, not sure what voltage was on them but enough to not want you hanging on, so it would be a good idea to do it.

Actually to be totally safe the machines should be plugged into GFCI's, ground fault interrupters, if the rails are grounded then that's all you need, if not, then you need to ground them. If you have a relatively modern house that has the center ground lug on the receptacles(and that lug is actually grounded) then you can just buy a GFCI unit and plug it into the wall and then plug your surge protector into that in case there is a lightning strike, the higher Joules rating the better.