Track your rides and runs via your iPhone, Android or GPS device, analyze your performance, and compare with friends.
That means performance improvement ;-)
Yeah, indeed on Ambit3 I got performance index from 45 to 50 in a few months
Phew! Big improvement
I was 52-53 at peak last season. But lost a lot over the pre and post surgery period. Anyway performance index is the main reason I'm not switching to spartan yet