Sunday, August 26, 2012

Living with GPS tracking errors

Today's run (street): 6.8 miles

My GPS watch always shorts distance, usually by about 3%, but this week the margin of error has been closer to 5%. If the GPS was more accurate, I could know my true performance as I ran. The Garmin FR210 does give me a map of where I ran, and this is useful when I run in unfamiliar places or forget which streets I covered.

An alternate to GPS tracking is the foot pod that, when calibrated, is far more accurate.  Its downside, besides the need to calibrate, is the lack of course mapping and the need to affix it to your shoe. Some shoes, like the Saucony Hattori, don't have laces and, therefore, cannot be easily used with a foot pod.

My plan for today's run was to go out easy and stay that way for five to six miles. I pushed hard on my runs during the week and I tried to do the same during yesterday's run. I figured I'd earned the right to ease up on my pace and enjoy the experience today.

Things started well and along the first mile I wondered how long it would be before I broke a sweat. I also knew that runs like these are deceptive, often becoming much harder after a few miles. After 25 minutes I was certainly sweating, but five minutes later I began to feel energized again. I spent half of the run going around the neighborhood that sits directly to the south of mine, and the other half going around local streets.

As I got close to home I saw that I was nearing six miles. I decided to detour north rather than follow my usual roads, in order to get some extra distance. That change added a half mile according to the Garmin. After plotting my run on Gmaps, I saw that I'd actually covered 6.8 miles. If I knew I was that close to seven, I would have run another quarter mile before calling it a workout.

Even though I took it easy, by the end it felt very hard. I was glad to exceed 6.2 miles, which I'll need to do as often as I can before the Cow Harbor race in mid-September.

No comments:

Post a Comment

Comments are most welcome!

 

blogger templates | Webtalks