Normalized Power (NP) is a power averaging method, measured in watts, used to compensate for changes in ride conditions for a more accurate depiction of power expenditure.
Conventional power measurement is based off of a steady resistance. Riding on a bike trainer or stationary cycle provides a steady resistance allowing conventional methods to give you an accurate power reading. However, riding outdoors produces changes in resistance (e.g., changes in elevation, terrain, or wind). NP takes into account the changing resistances to provide more accurate power output data.
The purpose this serves is directly related to your training. NP takes into account your body's reaction to change in exercise intensity due to changing resistance. This allows for a more accurate representation of your power output which in turn allows you to train within more realistic power confines. This gives way to a more productive training session.
Normalized power will show on the Edge 810, 800, 510, 500 and the Forerunner 910XT. If normalized power is notan optional data field, update the software.
You will find NP in Garmin Connect on the activity's Details page. There will be a Power section within the Details box.
For more detailed information on NP, view the Training Peaks' web site.
Update - http://connect.garmin.com/firmware