For my running program, this has been a year of firsts: In January, I bought my first MP3 player since 1999 and started running with music. Music! But music doesn’t make you faster. My inner engineer decided that more data was needed. A few months ago, Garmin released the FR60, the first product that correlates foot-pod accelerometer and heart rate data in an agreeable-looking digital watch. I know several people who are fans of the similar Nike+ system, and I’ve often wondered about these foot pods—are they at all accurate? Garmin’s literature promised “98% accuracy,” which is good enough for me, so I bought one.
Turns out, Garmin lies. My first run with the watch was a huge letdown: the instantaneous pace readout, the main feature that led me to purchase the product, was indicating more than 1 minute slower (per mile) than I believed I was running based on old-fashioned estimation. That would represent an error of more than 12%. To check my sanity, I borrowed a fancier watch that uses GPS, not accelerometer data, to calculate speed. I did a quick jog/walk with both products and correlated the data shown here: GPS speed (Forerunner 305) in blue, foot-pod speed (FR60) in red. Sure enough, my speed estimates were more accurate than the watch readout! But I was surprised to see the correlation improve dramatically during walking.
While Garmin makes no effort to call out its necessity, the FR60 offers a calibration procedure to improve the foot-pod accuracy. Will calibration improve running-speed accuracy at the expense of walking? We’ll find out in part two.