Sounds like static electricity as a result of the friction between the belt and your shoes. I build it up on my treadmill and get shocked when I touch the frame. Sounds like in your case it builds up, and discharges through the ear buds since they are likely grounded to the frame. Touch the frame every so often to discharge yourself. I wanna go fast!
that's funny. our gym also recently upgraded to similar treadmills (the new Life Fitness models with LCD touch screens) and I had the same thing happen. it's most likely static build-up from the spinning rubber belt and every so often when your head phone cord hits the metal frame...zapp.....i found it to be more of an annoying zapp than a nasty shock.
run your headphone cord through your shirt or holding it so that it doesn't touch the metal should prevent this.
actually I'm surprised the machines don't have better grounding.
This used to happen to me a lot - but not every time.
The first time it happened was with new buds so I took them back.
The next ones I got worked fine, then one day, zap zap zap! So I put them away, the next time I used them everything was ok, then another time, zap zap zap. WTF?
The only thing I can figure out is that it starts to happen when I am on treadmill for a while and someone new comes in my vicinity - maybe they are carrying a lot of static electricity. It happens now very infrequently, but if I get that first zap, I am done for the day.
Yes! I am a big head sweater, and after a few nasty zzzaps I never put those things on again. Don't want my brain to be a ground. The static electricity idea might be correct. Those jolts I felt were substantial. I still continued to use the treadmills until two of us were doing an interval on adjacent machines and overloaded the shared circuit, causing both treadmills to stop simultaneously. Now I know that you can fly off the back AND the front of a treadmill.
I've tried running while holding the cord in the air so it wouldn't touch anything, but I still got zapped. So i don't think it's a matter of the chord hitting the frame. I DO think it's static, though. I just can't figure out how to stop it. Sometimes, the shock is substantial.
Half my life is over and I have nothing to show for it. Nothing. I'm a thumbprint on the window of a skyscraper. I'm a smudge of excrement on a tissue surging out to sea with a million tons of raw sewage.
If there is an emergency stop cord on the treadmill,try clipping it to yourself and see if that acts as a ground. The other way would be to make a jumper wire with some light gage wire and aligator clips from Radio Shack (or somewhere like it) and grounding yourself to the machine. Look dorky but it would end your shocks. People would only laugh until they realized you were the only one left with earbuds in.