Foot pod vs treadmill vs rpe

ejbeach01

okay...I'm not sure what to think.  I posted something similar in the Nov OS discussion.



I did the run on the treadmill at the gym yesterday. I also have a garmin footpod.

Last week prior to the 5k test I calibrated the foot pod ata 450m track and it came in pretty darn close to the factory setting. When I ran the 5k I noticed the pace it gave me was pretty close to the lap splits I was getting. Not perfect, but really darn close. That test was around a 6:30 pace for the total run.  The garmin calibration only allowed for an 800m test...so I did guestimate that on the track.  But I took lap splits and was keeping any eye on my pace for the run...it was really pretty close. 



Fast forward today and I am in the same shoes with the footpod untouched or moved. I hop on the treadmill and start off with my warmup just fine. Pace seems fairly close to the treadmill. I do some strides to warm up and notice a bigger difference. But the speed on the TM feels about right.



I hit the main set and punch in 9.3mph on the treadmill which is about a 6:25ish pace. And frankly, like the bike set, it didn't really feel that bad. But the garmin was reading between 5:55 and 6min pace. And that difference seemed incredibly large.

I held that pace for the entire set, no problem. I even did 12min at z3 towards the end of the workout to finish up.



But now I don't know what to believe...the treadmill or the garmin.

This is the first time I've really gone and run 200's or 400's and the track was covered with snow and slush.

According to WKO, the garmin footpod was very consistent from rep to rep. little to no deviation in the pace it read.

Thoughts?

gschlossnagle

I've had absolutely awful luck with the accuracy on the Garmin footpods. Similar results to what you are experience. At first I (hoped) it was a treadmill calibration error, but in the end convinced myself that it was the Garmin that was off. Confirmation came by wearing the footpod in a couple races and having it report my outdoor pace (through the footpod) incorrectly.

TH3 FRB

Several potential issues here.

1) Treadmill speed/pace is very unreliable - it is likely +/- some non-trivial margin.

2) The calibration of your footpod is specific to the surface you were running on and the general pace you were running at the time of the calibration. So there are 2 issues here

2a) The moving belt of the treadmill is different from running on solid ground and the forces the foot pod measures will be different = different calibration. Same holds true if you calibrate on the road and then go running on dirt trails.

2b) If you do a calibration while jogging your stride mechanics have specific properties. Iif you then do sprints the foot-strike properties will be different and again, the foot pod will probably not be experiencing the same forces and won't calculate your pace/distance as accurately. I'm not sure how much of a factor this is but the physics say it's real. Could be within the error of the foot pod though and not really matter.

My best advice would be to ignore the foot pod on the treadmill and try to always use the same treadmill so at least you know you have consistent measures of pace between treadmill workouts even if you don't know exactly how it compares to your real pace on the road.

Even better for outside - check out the new Garmin 110 GPS and don't worry about the calibration issues of the foot pod. I still use my foot pod to track cadence but run with a FR405 for pace/distance.

mgraffeo

I and several others have had very good luck calibrating on a 400m track at about z4 pace, and then using it indoors on the treadmill. It stays pretty accurate from z3 to z5, and is slightly slow for z1-2. I haven't experienced any of the problems that Joel alludes to, and even switch from shoe to shoe without problems. It calibrates to the path/shape of the foot strike, so it shouldnt be as sensitive as some people find it.

More often than not, the people i've see have issues are able to resolve them with a proper calibration.