HR recovery is one of many markers of aerobic capacity
@aciampa can probably clarify this better than me. The HR recovery indicates that the body is good at buffering the by-products of fast-twitch fiber glycolysis, and this buffering takes place largely in the slow-twitch aerobic fibers. Well-developed slow-twitch fibers, along with the capillaries that support them, and the heart and lung improvements that support the gas exchange for work fueled by the aerobic energy system, all contribute to "aerobic capacity." Other good markers for aerobic capacity are your overall endurance through an active day and how much work you can do while still remaining aerobic (easy, nose breathing, MAF HR, etc.).
From my perspective, yes, I believe MAF runs or bike rides would improve your aerobic capacity. I am on the tail-end of Week 7 of a program to do just that, so we're learning as we go. You are welcome to visit my
training log for more detail. That link takes you to 10/18/16 when I started this program.