I've never heard of this and can't really see what is radioactive about these machines?
They are just mechanical... not like a Microwave or a phone.
What type of machines are we talking here? If it really worries you there are powerless ones you can use... rowing machines and running machines that offer either wind or magnetic resistance.
I don't use any machines, just a heavy bag, the ring and the pavement so I don't have a huge amount of knowlodge on this but unless your tread mill is being powered by plutonium I can't see why this would be the case...
Don't take my word for it though, you should ask your freind where she heard this and if she knows why.
Oh and get your arse into Ask the Trainer! :P
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