I first learned about the different energy systems in the book 4 Hour Body by Tim Ferriss. He had inserted an ultrarunning/marathon program by a Crossfit practictioner named Brian MacKenzie (see Super Running: Is Crossfit Endurance The New Way To Train? who had crafted his training program based on training the 3 energy systems present in everybody. Crossfit founder Greg Glassman wrote about it in one of his Crossfit Journals entitled Metabolic Conditioning.
Then in the course of roaming around the net, I found reference to it in a presentation by Joel Jamieson, a MMA fighter trainer based in Washington State. Check it out in his post Truth About Energy Systems FREE Video. He also discusses it in his interesting book Ultimate MMA Conditioning Guide to fitness for MMA, Jiu Jitsu and Combat Sports by Joel Jamieson.
Is it Alactic or Phosphagen, or Lactic or Glycolytic, or Oxidative or Aerobic, I'm not sure which terms are the right ones. But it's interesting to see people developing athletes with all 3 energy systems in mind and how they interrelate.
The one thing to note is in Joel's presentation, which was about how the aerobic system kicks in to supply energy pretty quickly, within 15 to 30 seconds. He found that without bringing back roadwork and other similar types of training to develop the aerobic system, his fighters were running out of steam in their fights. When he brought that training back, his fighters did much better and were able to maintain higher intensities for a longer period of time.
There is a lot of controversy about high intensity intervals and whether or not they can develop your aerobic endurance for a given length of time without actually having to put in that much time. Crossfit's position is that you don't need to train for that long; you can get there with their training methods by taking their classes. Joel tried it and it didn't work; his fighters needed more classic aerobic work.
Still Joel's book and Crossfit principles are very interesting in developing more overall body strength and designing the training to reflect stimulus of each energy system. In looking back through my training, I can see where I've either left out stimulus of 1-2 energy systems, or I haven't trained them properly, meaning I did train them and then the energy system atrophied by the time race day came because I moved on towards aerobic system development.
There is much to learn here and when I get the chance I will apply them in my own training.