Burns Battery very fast

Greetings:
This App is very good, it works perfectly.
But when I do a session for about 1 hour, the app burns battery power very fast.
Also the App will not count my steps if I dim the screen, or put my Ipod Touch in sleep mode.
Other than that the App is worth the 99cents.
Regards Robert

RobMtl007 about Footsteps Pedometer, v3.5