http://www.android.com/versions/kit-kat-4-4
Step counting built-in
When you use fitness apps like Moves on Nexus 5, the phone acts as a pedometer to count steps. Android 4.4 and updated hardware make this a more battery-friendly way to measure your activity.
http://developer.android.com/about/versions/kitkat.html
Step detector and counter sensors are available on Nexus 5, and we're working with our chipset partners to bring them to new devices as soon as possible.
La fuente es google, así que parece fiable
slds