Mechanically, there are only two ways to run faster:
- Increase the length of your stride
- Increase your number of steps
That's really it. The hard part is doing this correctly. To accomplish both of these things you need: Strength, especially in your core, lower body, and even your feet (yes your feet). Having bulky thighs, calves, and arms doesn't matter really and can actually hurt your speed, but you should cross-train with resistance training of some kind regularly.
