AllSport GPS thinks I'm a slacker

I'm in taper mode as I move closer to Sunday's race and I'm also experiencing some discomfort with the outside toes on both feet. I decided that I would get a run in today but take it easier than I normally would. I brought along my iPhone and selected the AllSport GPS app to track my run and took the Garmin 50 along as well. I now have five GPS apps on the iPhone: Allsport and MotionX (paid apps) plus iMapMyRun, Run Keeper Free and RunGypsy (free apps) and they all capture data about run speed and distance. What separates these apps is what else they track and how they report data. The free apps generally give you pace and distance information and some rudimentary resources to store that data. The paid apps have lots of features, MotionX really provides a lot of utilities for the running experience including compass, mapping and music integration. AllSport generates an excellent report that shows many metrics including elevation (as does MotionX) and both paid apps export KMZ and GPX files that overlay on Google Earth.

The thing that these apps all have in common (though I have not yet tried RunGypsy) is a dependence on the iPhone's GPS service which has proven lacking. Each time I have captured a run with one of these apps I've seen differences between what's reported and what was actually run. My baseline is Google Earth where I can trace my route to the inch and compare it to the route created by the GPS apps. This morning I verified on Google that I covered 2.15 miles and the Garmin confirmed that. The AllSport app reported that I ran 1.98 miles and I can understand why after reviewing the route it displayed. There seemed to be some weak links from the signal (that were shown as yellow lines on the map) and the lines veered off the road enough to explain the shorter distance. What puzzles me is AllSport's insistence that I rested for 7:17 of my run.

Now I know I wasn't pushing too hard today (my actual pace was 9:39) but I don't recall resting during the run. It's not clear if that was a result of a weak signal or if AllSport was judging me for not picking up the pace (yes, I'm kidding). I sent them a note asking about it and I expect that I'll hear back. To their credit they've been good about responding to my questions. I like this app a lot but I want to rely on it and at this point I don't think I can. I'll try to use it on Sunday so I can capture the route but I'll have my Garmin 50 along to keep things honest.