Can't help. But got the same question.
I'm on an iPhone 4. Tried the Pedometer App from Runtastic but it seems to eat a lot of battery power even when the phone's sitting idle on my desk. (Phone lost 6% charge within 10min, not doing anything else but having the pedometer app running in the background).
My girl-friend's on a Galaxy S3 mini and has an app that hardly has any impact on battery life. But that app is not available for iPhone.
Surely there most be something for iPhone that just works & doesn't drain the battery. (I would very much prefer not having to turn the app on and off each time I walk around...)
