Mobile accelerometer and suspended mode rate

Hi!

I am building an app that will, among other things, act as a pedometer.  After much sweat I managed to build a pretty reliable code to detect steps by using, among other things, a dot product of the three axes values and a weighted moving average to smooth the result.  Now the problem I seem to be struggling with is when the app is in background.  The update event rate seems to be ~2x slower (4-5 updates per second) and sometimes the movement doesn't seem to register at all.

I am testing on IOS, on Android I have yet to manage having the accelerometer work in background at all.

Is it a bug? Is there something I can do?

Any help would be really appreciated.

Thanks!