It records all your heart rate info wirelessly via the robust ANT + Sport wireless heart rate monitor (sold separately). It tells you how far, how fast and when you are in your heart rate zone. While indoors, ANT + Sport technology allows you to connect to an optional foot pod to track your distance, pace and calories burned when GPS reception is not available. While out, this personal trainer's high sensitivity GPS receiver provides improved tracking under trees and near tall buildings. An optional speed/cadence sensor (sold separately) allows you to monitor pedaling cadence and wheel speed. And each workout is stored in memory so you can review