Garmin Track Tempos

GPSs don't read right on tracks. For obvious reasons. It plots a series of points and draws a line between them and measures the line, but there can be several feet of left to right error fixing each point. This makes no difference on a long straight, but plays havoc on a tight turn. Plot your run on Google Earth and you can see exactly what it does. The error will be significant.

It might take 20 readings during each turn (if you have "every second" updating) and it might think you are in lane 3 on one reading and a few feet into the infield on the next. Move the tracks to Google Earth and it is easy to see how this error is made. There is smoothing software that tries to solve the tangent cutting problem, but it isn't perfect.

GPSs are good on courses with long straights or gently curving roads. Not as good with lots of tight turns or trails with switchbacks.

And a given pace on the track is always easier than that same pace on the roads, even without hills. At least to me.

Just press start and run, press the lap button at your splits, and press stop when you finish. You will not get good distance measurements on a track so don't worry about that. Although it will kinda sorta help you know roughly where you are in your tempo so you won't have to count laps. Go from line to line and hand time it. You'll be able to track whatever pace you set your watch to show.

I have never used a gps watch and never want to. Some of my teammates have them. We've done workouts where the watch told us mile X was in 5:50 and mile Y was in 5:03, even though the two were likely within 10 seconds of each other. I don't trust them and find them unnecessary. If you want to know what pace you're running, measure out a loop online, or measure out a few 1 mile distances within a loop to check your pace (this is what I do). I do my short "true" threshold workouts on the track, and anything longer than 5 miles I do on the roads usually and go by feel. It has worked well for me.

Especially on the track, if you know how many laps you ran and what time you ran, it is pretty easy to compute the pace. You might not get a breakdown by mile, but if you simply press the lap button at the end of each mile you should be right on the money. Forget what distance the watch says.

The Garmin 310XT is more accurate than previous models and is more accurate than mapmyrun.com on any course with enough turns so that staying on the inside matters as mapmyrun.com measures the middle of the road. It measures straight lines pretty much the same as my 310XT (with "every second" updating).

My 310XT has amazing internal consistency (that is, it measures the same courses the same distance every time down to the hundredth, neverminding whether that distance is accurate) and on certified courses I have had it on it is very accurate.

Mapmyrun only measures in the middle of the road if you're too lazy to zoom in and accurately map your course.

That would be like saying GPS watches don't work for me when I wrap my wrist in aluminum foil and run indoors. Don't blame a tool that you're not using properly.