Default vs. Personalized Heart Rate Zones (an example)

For those who are into heart rates and charts, I wanted to share these Garmin readouts of time spent in heart rate zones of 2 bike rides. The rides were a few weeks apart. I rode with the same group of people, same weather, same bike, same distance, same elevation in the same area (though different routes). My average and max heart rates were also nearly the same on both rides. The big difference is that I had a fitness test between them. I went to a physiology lab to test VO2 max, lactate threshold, max heart rate, and ventilatory values. The left graph is the time spent in each heart rate zone using Garmin's estimated zones. The right graph uses the personalized zones the physiologists set me up with.

The only real difference is my VO2 max. Garmin (and every generic calculation out there) correctly estimated my max heart rate and lactate threshold. But my VO2 max proved to be several orders off. I just thought the difference was interesting and worth sharing. For what it's worth, the personalized chart more closely matched my perceived exertion. At no point on either ride did I ever feel like I was pushing my limits, these were both casual weekend rides.