What are commonly referred to as “Vo2max” intervals also work your anaerobic energy pathways. You break the glycogen anaerobically and that creates energy, and the lactate and pyruvate that is produced get burned aerobically too. It’s a continuum. So all this stuff about 'this is anaerobic, this is aerobic," trying to draw too hard and fast of a line is usually wrong.
and yes, you can hold onto this with short, hard intervals, and there’s no reason not to try. What makes it go away is stuff like sweet spot and threshold. Those intervals allow you to use a larger percentage of your Vo2max sustainably, but often at the expense of the strength of the anaerobic system.
