I've also wanted to mention one thing that I've heard from some coaches from my old school; The coach for my row in gym which I had from 6th to 8th was really impressed in the talent I had in middle distance running, and called my parents to meet with him outside of conference day. As I talked to him more and more, he mentioned that "aerobic" running will shorten your recovery time, but after reading interval training science articles, they too shorten recovery time.
So therefore, I don't find much use in using AT training to improve performance because in fact, I remember seeing an article on here that humans have the best endurance in the world. So basically long, slow, easy runs are useless for one's performance. Instead there are two types of runs that increase performance. They are intervals, and aerobic power training. Aerobic power is basically running non-stop but at an unsteady pace. It's not fast pace, but uneasy pace.
On the other hand, intervals are done at a faster pace, but they are done in repetitions which would make them a hybrid between endurance, and speed training. There have been numerous tests besides performance if interval training stimulates fat loss better than aerobic training, and the results were clear: intervals are indeed, more effective in every way (performance, fat loss, healthwise) than aerobic running, but with one downside: they require a lot of determination to do. After every painful, blood-draining interval session, it always feels better than doing an aerobic session. One feels much more relaxed after intervals, because it's such a large leap from high intensity to that relaxed state after exercise.
Here's another fact that I've been impressed by; interval training recruits more muscle fibers than aerobic running. Not only are the benefits a lot better performance, and health wise, but intervals allow for a more sculpted body too, more defined. The small inferior muscles that are not used in aerobic running will remain that way, and not have such a big effect on the appearance of one's body. The difference is clear; if we compare professional runners' physiques from today with the past, today's runners actually appear more toned, powerful, etc. due to the introduction of intervals. In the future, there is a high probability that the training regimen of elite athletes will consist more of intervals than aerobic running.
