This video nicely illustrates the impact of altitude on running performance. Notice the riggy shuffle in spite of the downward grade...don't care...doesn't bother me because for the first time in many years I ran for more than an hour without crossing a street or seeing a single person. I want to live in Colorado.

Here are a few more pics from the run (disclosure: photos taken with my phone and may not reflect the outstanding quality that you take for granted)