Garmin vs. Nike GPS App

Sunday's run produced another technology conundrum;  my Garmin inexplicably died.  I charged it the night before, and it was ready to go.  Until it came run time, about 3 pm, and was dead.  As in nothing, no power.  I turned it on for a second, got a 0% battery reading and then it died.  The I got a hammer and smashed it into a million pieces.  Ok, I didn't do that, but, seriously, the power issue is a joke: it seemingly dies about once a month. 

Not to be without technology, I figured I would try the Nike GPS app on my cell phone.  And I was going to run a route I knew well, and knew where the Garmin GPS made mile marks.  Of course the Nike app is on cell phone, which got tucked away in a pocket, so I couldn't stare at it midrun, but it did provide audio updates at the mile marks. "Mile 2 completed.  Time is 18:00, average pace is 9:00 per mile."  So at the Nike first mile mark, which was about 100 yards past the Garmin mile 1, it had me at 9:57 mile.  WHAT?  I am pretty consistent in my pacing and was running about 8:45 or so. And this was a downhill mile. So, to be really under (over?) pace was disturbing, particularly with an uphill mile coming.  But I kept on my pace, figuring it was a tech glitch of some sort.   The Nike miles were about in the same places as Garmin miles.  And the pace picked up.  After 5 miles, Nike had me averaging, 8:50/mile.  If the first mile was off by about 1:20 or so (which is what I suspected), then the run was right at 8:30 miles.  Overall, it had my route slightly shorter than Garmin, and a corresponding higher average pace. 

I looked at the map on Nike running map, and lets just say, the GPS wasn't exactly on.  Fewer data points meant much of the detail was lost, producing cut corners, seemingly random wandering into houses, course corrections and the like.  Wasn't all wrong, but sure wasn't accurate.  Even Gmap Pedometer has an option to limit your route to streets, which calculates the route 0.18 miles longer than Nike (and about 0.08 longer than Garmin).  Maybe off the grid in the wilderness without a lot of turns, it works better, but for my route, I would have completely freaked out if I was trying to run to an accurate training pace.  I guess my bottom line on Nike GPS app: a good general app, very easy to use.  Tracking is Ok, and much better than nothing, provides a good general idea, but not one to take to the bank or to take too seriously.  If I was stuck somewhere without my garmin (or if it inexplicably died), I would not hesitate to use the Nike App to give me an idea of my workout, but not an app to base results, pacing or training from.