A few days after arriving in Mexico City, I go for a run to get used to the difference in altitude. Going from 200 to 7300 feet affects you, but it’s one thing to read the theory, and another to actually see the numbers of a runner while he’s doing it. Here we go on a long run and share how it feels, what is affected (hint: some of the predicted changes didn’t happen to me) and what you can do to understand and adapt to high altitude running. Along the way, we also weave and wind our way through the crazy traffic in one of the busiest cities in the world!