The human body is an amazing machine capable of great feats, and uncanny speed is one of those feats.
Recapping the previous article; speed requires a flexible, toned body, the understanding that running is only a portion of speed building, and that specific exercises outside of lifting weights are best to increase speed.
Many athletes know that speed can be divided into two ideas; acceleration, or the rate at which one reaches top speed, and the top speed itself. While many sports based on running like relay races, soccer, and swimming focus on top speed, other sports like point fighting, fencing, and foot ball may focus more on acceleration, or even both ideas equally.
For those who wish to focus on acceleration it is important to understand which muscle groups are used, and how. Maximum-Maximorum provides this great PDF. It's a very comprehensive read, but the information is present.
A snippet from the PDF states: "The erector spinae (muscles of the back) participate in acceleration yet a rounding of the back diminishes the response. The ES is capable of rotating the pelvis and so can transfer energy through the pelvis to aid the legs in applying force to the ground."
This information can be crucial in helping you better understand training videos like these.
Speed training acceleration on Youtube
Push up start on Youtube
Fencing development on Youtube
For more on speed training, this presentation regarding the late Bruce Lee's take on training cannot be emphasized enough. He was a man consumed by the endless possibilities the human body provides.
Always consult your physician before starting a new work out routine.