The Wikipedia definition of Endurance Training is:
The term endurance training generally refers to training the aerobic system as opposed to the anaerobic system.
This chart in the Wikipedia article shows the heart rate range associated with aerobic training as 70-80% of max heart rate.
This is a form of Aerobic Training is also known as “Long slow distance training“.
Richard Diaz on WodCast Podcast Episode 323 talks about why CrossFit fails in the area of aerobic training. He explains how VO2max testing works and why Crossfit doesn’t produce the sort of VO2max numbers that they would expect (I got at the bottom end of good on my VO2max after nearly a year on Crossfit). He also explains the benefits of training aerobically. He has some critiques of Maffetone’s method for competitive athletes.
A helpful page with a descriptive title (Training with the Maffetone Method: 7 Tips for Beginners).