Speed is the most precious of all the biomotor qualities. It is dependent of fine motor control, coordination and explosiveness. That being said, training speed out of someone is simply emphasizing the type of training that negates those qualities. Speed and Endurance are at opposite end of the spectrum. You can train both, but not to the fullest extent of each at the same time. There must always be a thread of speed development work throughout a program in any sport. If you get too far away from speed then it is hard to get it back because it such a neural quality. The concept of “Training speed through endurance” is contradictory and basically fallacious. I conceptualize speed as an electric shock that excites the nervous system. For the middle distance and distance athlete and any sport that has an endurance component this is a good way to think about it. Use it wisely, do not overdue and remember that speed development must have a foundation of good movement mechanics for optimal development.