Thursday, October 30, 2014

Calibrating a foot pod to a Garmin Forerunner 620

My sister wanted some help calibrating the foot pod for her Garmin 620, so I spent a while this morning searching for any info I could find. I've tried to get an answer from Garmin several times over the past year about it, but I've never gotten a response (I love my Garmin, but their customer service is terrible). I knew that there was a calibration factor (a number that is factory set at 100.0), but I had no idea what that number meant. So this morning, I was determined to find out.

I calibrated my foot pod a long time ago with the 910XT, but I've noticed that it's been "off" lately when I've used it, showing that I'm going a slower pace than I actually am running. After a ton of searching online, I found out how to manually calibrate the foot pod (the newer Garmin Forerunners don't have the calibration tool built in), and I actually understand what the number means now.

If anyone is interested, to calibrate the foot pod to the Garmin Forerunner 620:

1) On the watch, go to Settings - Sensors - Foot Pod - Calibration Factor
2) If it's not already, set it to 100.0% (this just makes the math easier later)
3) Choose a measured course to run (ideally, this would be a 400-meter track, but you could also use a treadmill if you want to calibrate the watch to read the same as what the treadmill shows).
4) Start the watch, and run 800 meters (you could run farther, but make sure to do at least 800). Note: Run the 800 meters as measured by the track or treadmill--just ignore the watch for now, because it probably won't be accurate. Stop the watch when you're done.
5) Take note of the distance that is shown on the watch.
6) Use this formula to figure out the calibration factor:
    Actual distance in meters/(recorded distance x current calibration)
   
For example: You run 800 meters on a track, but the Garmin showed that you ran 0.48 miles. Convert the miles to meters (I just use Google to do that for me), and you get 772 meters. So you plug in the numbers... 800/(772 x 1.000) = 1.036. So the new calibration factor needs to be changed to 103.6% (see step 1).

The number just shows that you ran 103.6% of what the Garmin was showing (slightly faster).

That was a whole lotta math, but you know I love numbers, so it was fun for me ;)

I had three miles at goal race pace on the schedule today. My goal is a sub-2:00 half-marathon, which is a 9:10/mi pace. So My goal for today's run was to stay between 9:00 and 9:10 per mile. (When you run a half-marathon, the total distance is usually longer than 13.1 miles, due to weaving and not hitting the course tangents. So I like to have a small buffer in my pace, aiming for about 5-10 seconds per mile faster than needed.)

I wanted to calibrate my foot pod, so I went to the high school track. I decided to run 800 meters as a warm-up, and calibrate the foot pod with that number, then run my 3-miler at goal race pace. I ran at an easy pace for the calibration, then cleared my Garmin and started the goal pace run (using GPS, not the foot pod).

My legs were tired today! I'm not sure doing cross-training the day before a goal pace run was a good idea. I wasn't sore (well, except the bones in my butt! They feel bruised from the seat of my bike), but my legs were definitely feeling tired. I did really well at holding pace, even though it felt very hard today.



I'd like to go back to the track and use the foot pod rather than GPS, just to see how accurate it is when I run at all different speeds. Maybe I'll do that next week. I'm hoping to not have to use the treadmill much this winter, like I did last winter; but if I do, I'd like my foot pod to be accurate.


I've been really consumed with a missing persons case for the past few days. On Saturday night, there was a house a few miles from me (actually, it's on my favorite long run route) that had a Halloween party. It was a huge party, with upwards of 600 people there. The house is surrounded by cornfields and woods, and it's a pretty rural area. There was a 22-year old woman named Chelsea Bruck at the party who went missing sometime around 2:00 a.m. Sunday.

She didn't have her cell phone or purse with her (she left them in a friend's car). Supposedly, someone saw her talking to a guy near where the cars were parked, so he is now a person of interest. But there are truly no real leads on this case--it's like she just vanished.

I've been seeing several news vans there all week, and they've had search parties and candlelight vigils. Here is the poster they've been handing out (click to enlarge):


The police have also released a sketch of the person of interest:



I didn't know her, but because this was so close to my house, I've been following the case really closely. Her case was on Nancy Grace tonight, so hopefully they'll get some new leads. I just really hope that Chelsea is alive and comes home safely! It's so scary how someone can disappear just like that.