Exclusive Zone 2 training would widen the aerobic base and also raise peak capacity, while higher intensity training would increase peak capacity and also widen the base slightly.

“Um, that you know zone 2 is what you do exclusively to build your base and high-intensity workouts is the only thing you do to build your peak. Um, as I said, these systems work together. And if all you did was zone two, you would absolutely get a wider base. You would also raise your peak. Um, similarly, if you did, you know, higher intensity training, you would increase your peak, but you would also widen your base a little bit.”