Although his speed-based training system had taken the sport forward from where it had stood when Zátopek found it, that system proved to be a dead end. He had shown that high-intensity intervals were a vital ingredient in the training of distance runners, but in the final analysis, it seemed their place was rather smaller than Zátopek (and Nurmi) had anticipated. If future generations of runners were going to run even faster, they would have to do so by some means other than speed-based training.
