The 620 is the first GPS running watch that provides feedback on your running form by reporting multiple metrics. When used with the HRM-Run monitor1, the 620 reports your cadence, vertical oscillation and ground contact time. These metrics are called running dynamics, and they effect your running economy.
The HRM-Run has an accelerometer, which measures your torso movement as you run to compute these metrics. Cadence is the total number of steps you take per minute, left and right foot combined. Vertical oscillation is the degree of “bounce” in your running motion, measured in centimeters. Ground contact time is just like it sounds — the amount of time your foot spends on the ground during each running step, measured in milliseconds. A color gauge makes it easy to see how your running dynamics compare to other runners.