Here's something that also touches on the concept. This is in a site called Science of Baseball.
When you pick up a baseball, it immediately suggests its purpose: to be thrown fast and with considerable accuracy. The pitcher, with his dance-like windup, prepares to do exactly that by transferring momentum from his body to the ball. To appreciate why this is necessary, try throwing a ball without moving your feet; it's difficult to throw it very far or very hard, but a forward step makes throwing much easier. So during the windup, the pitcher moves his entire body weight back behind the pitching rubber. Then he thrusts it forward to deliver the pitch.
This transfer of momentum from body to ball involves a biomechanical principle called sequential summation of movement. According to this principle, the largest body masses move first, followed by progressively smaller ones, in much the same way a multi-stage booster rocket jettisons a satellite into space: the large booster starts the process, is jettisoned, then is followed by the burning and jettisoning of progressively smaller and faster stages, until finally the small satellite is released at high speed. In baseball, the pitcher drives first with his legs, then his hips, shoulders, arm, wrist and fingers. As each part approaches full extension, the next part in the sequence begins to move, efficiently transferring momentum in a whip-like action. Proper timing is necessary to produce speed and accuracy, and to avoid strain and injury.
As I've explained to many... The thing about baseball is that you get direct feedback. As kids we don't talk much about mechanics because the ball doesn't lie. Like the Nike mantra, we just do it. If you throw it well, the ball goes far/fast/straight. If you don't, it doesn't do one or more of the above. The Platonic ideal in baseball is to have both power AND precision. You need both to hit a home run, as you need to hit a moving ball with maximum force while sending it out at a very, very narrow angle off the bat. Some martial arts "experts" would have you believe that you can't have both power and precision - particularly when neurohormonally juiced. For most, this is true. For the elite fighters, well they can get both power and complex motor coordination if they use their bodies correctly. And that would be if they use their core (the large muscles) for power, and use the periphery (the muscles in our extremities) to guide and shape the power that flows in a wave-like fashion from the core.
The problem with traditional martial arts is that we spend a lot of time with choreography (a.k.a. kata). That's all fine and good, except that we get no feedback when splitting air molecules with our punches (of doom). Just because we generate a lot of power doesn't mean we efficiently deliver said power to the target. One needs only to compare automobiles made in the muscle car era of the 1960s vs. those made today to understand that. You can huff and puff and make the gi snap and have a killer face (of doom), and yet be nothing more than a sheep in wolf's clothing because damn little of that energy is going out the fist. So one has to pay extra special attention to form while doing kata in order to prevent delusional martial arts.
Bill Stockey (hanshi from my former style) and I were discussing this at camp. He was wondering why Uechi Ryu as a former Chinese style didn't start with weapon work per the usual Shaolin Temple method. The reason for weapon work wasn't necessarily to get good at using the fancy weapons. It was instead to give someone a load to put on the hands so one could get feedback on the efficiency and productivity of movement.
Anyhow... here are some good pictures of pitching masters to show the concept.
Note this sequence of pictures of Randy Johnson.
- Picture 1 is the start.
- In picture 2, he's creating potential energy by raising his step-forward leg and loading his rear plant leg.
- In picture 3 he has exploded forward by converting the potential energy of a raised leg to the kinetic energy of stepping forward. He's also driven off of the loaded leg. Note however how the ball is actually BEHIND him. The energy has been delivered from the big muscles of the legs/hips, and transferred to his torso and shoulder. They have stored this energy passively (viscoelastic properties of the muscles) and actively (triggering the dynamic stretch reflexes in his torso and his shoulder.)
- In the final picture he has released the stored energy in the torso/shoulder in a whip-like fashion by crunching at the waist, slinging his arm forward, extending the arm, snapping the wrist, and finally flicking the fingers. That happens not all-at-once, but rather in a sequential fashion (just like pictures 1 through 3 above). Each point that the energy wave hits "tweaks" the neuromuscular reflexes, and the trained body adds to the energy wave at each point.