Garmin vs Nike+: A Test of Accuracy

[ OBSERVATION ]

NOV. 3, SATURDAY. This was the first time I used my Garmin on a long run. Our goal with Annie, my running buddy, was 15 km around Ayala Alabang. We agreed on taking our usual 12 km route and just let our feet carry us an additional 3 km anywhere from that point. Boy, were we in for a surprise.

At the 12 km mark (according to Nike+ in the past), the Garmin recorded a distance of 9.5 km. “9.5?!” Annie shrieked in disbelief. I was likewise stunned at the awfully large discrepancy. At the very least, I was expecting to hit over 10 km by then.

Which gadget was telling the truth? Had I been logging less kilometers than I actually ran for the past 5 months? Should I have followed Nike’s directions and calibrated the kit before using it? All these questions were floating about in my mind as Annie and I plodded on with an unxepected 5.5 more kilometers to run.

[ TEST ]

NOV. 10, SATURDAY. At the risk of looking like Inspector Gadget, I wore both the Garmin and Nike+ on my next long run last Saturday.  Our goal this time was 18 km.  Again, we ran the same initial 12 km route then ran halfway through that same route making our way back to the starting point.

At the onset, both gadgets recorded the same distance.  At least, that’s how it was at 2 km.  But, as we increased our distance, the discrepancy increased as well.

For the pace, there was a significant 30 second difference too; the Nike+ giving me a faster pace than the Garmin.

At the same 12 km mark (based on the Nike+ in the past), the Garmin, much to my delight, registered the exact distance as the past week’s run: 9.5 km.  I pretty much knew which gadget was more accurate at that point.  And, sadly, our once favorite 12 km route needed an immediate name downgrade to “10 km route.”

[ RESULTS ]

Here are the actual data from both the Garmin Forerunner 305 and uncalibrated Nike+:

GARMIN: Time 2:01:15/ Distance 18.2 km/ Ave pace 6:4/ Calories 1028
NIKE+: Time 2:00:08/ Distance 20.5 km/ Ave pace 5:5/ Calories 1148

I get goosebumps thinking of what could have happened had I used the Nike+ to train for my upcoming marathon.  I would’ve been led to believe that I trained at my maximum 32 km when it might have been only 30 km or less.  Scary isn’t it?

* Note: At 8 km, I accidentally ended the Nike+ workout when we paused for a water break.  I started a new workout and added data from both workouts.

[ PREDICTION ]

I predict my Garmin Forerunner 305 will be my new best friend.

I predict my Nike+ will gather dust at home.

I predict I’ll get death threats from Nike+ fanatics who are running 2 kms less than they actually are.  (Please don’t kill the messenger.)