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I use a protective case attached to an armband when I run and bike. For sweat getting into the headphone switch, try wrapping a cotton ball, piece of sponge, or some other absorbent material around the headphone cord above the switch. Attach it with tape. Change it out each time you run.

Oh, and remember to go into Settings and turn off "shake to shuffle!"
 
I've been running with my iPhone a few times and almost every time i do, the headphone button stops working...I click and nothing happens. I'm thinking sweat is getting into the button and shorting it out or something cause if I wait awhile it works again (i.e. dries up).

Without that button, skipping to the next song on an iPhone is quite the P.I.T.A. while running. Anyone else have this issue?

I had the same thing happen and got my iPhone earbuds replaced for free via warranty. By design they are supposed to repel moisture and that wasn't the case for me.
 
I don't know what exactly was the deal but one day I was running with my iPhone and the earbud button didn't work and the iPod would randomly pause.

I don't know if it was because of the moisture on the screen or what but this is something that I ran into (everything is fine now).

Just a heads up, I'd recommend using your iPod just for protection/prevention reasons, but the iPhone is just so pretty. ;)

I had the same thing happen to me and it was because of voice dial via the mic. You can turn that off for a run or exercise activity by going to general >> passcode lock >> voicedial...
 
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