all of the other answers are absolutely correct in pointing out the important of genetics as we all are differently endowed with the distribution of muscle fibers.
The thing that struck me, though, was that you do not specify for what to make people faster; 100 m dash or marathon. No two training regimens could be more different but the goal is to make the runner faster.
Another aspect is speed in sports. Training for tennis, for example, is very different from any running drills.