※ [本文转录自 SFGiants 看板] 作者: abc12812 (abc12812) 看板: SFGiants 标题: Crossing the Bridge(4-3) 时间: Wed May 14 09:38:22 2008 I see the same thing happening in Zito's delivery. Seeing these problems is so difficult because at the major league level competition it takes only a small change in mechanics to decrease velocity by 5 mph (or more), making it virtually impossible for the coach or instructor to see the difference. And seeing is only at best half the problem. Seeing is one thing. Fixing is another. The two tools I have found most beneficial for understanding how the body throws the baseball are physics and physiology—the combination is also call biomechanics. Pitching mechanics or throwing mechanics are both poor cousins to what is really happening when the body throws the baseball. In my previous article I tried to show how physics simulations are used to better understand the throwing process. From a physiological (and kinesthetic) perspective I find three-dimensional simulations of the throwing process vitally important to understanding how the body throws the baseball. To create these simulations you have to understand not only the physics of the throwing process but also how each body part is contributing when it throws the baseball. Pushing the ball is the most common and also the most insidious throwing problem. A common form of pushing is also described as muscling the ball. Pushing the ball occurs when there is a break in the rotational sequence (kinetic chain). Attempting to get extension toward home plate is the most common cause of disconnection. Attempting to get a release point out in front or on top of the ball truncates rotation and contributes to a linear finish (disconnection). As previously stated, a north-south delivery has a greater propensity for disconnection. You can be a north-south pitcher if you have a certain amount of east-west (translational) rotation. But even the smallest loss of translational rotation can spell disaster for a north-south pitcher, as is the case with Zito. Disconnection occurs when rotational connection is lost between successive elements of the kinetic sequence. The simulation in Figure 4 demonstrates the disconnection principle. On the left-hand side we have a "connected" compound pendulum. On the right-hand side we have a compound pendulum which is connected until shortly before what would correspond to releasing of the ball (or making contact with the bat). The compound pendulum (on the left) stays connected achieves a maximum velocity at release point of the ball of 70 fps (feet per second). The compound pendulum on the left (that is disconnecting just before release) achieves a velocity just prior to release of 50 fps. There are a number of rotational centers when throwing the baseball. But the most important ones based on my observations are rotation around the front hip joint, rotation of the shoulders around the upper spine, and rotation of the scapular as it slides along the rib cage. These of the primary rotational centers responsible for creating a whipping action. Also critical to the whipping action is creating the “loop” in the throwing arm. This loop is composed of raised-forearm-upper arm-humeral joint. The loop is created primarily by the inertia of the forearm during rotation of the shoulders and bending forward to the upper torso. The key here is rotational connection must be maintained—a constant pulling action of each successive segment of the chain toward a rotational center point. For emphasis I have illustrated the rotational path of the connected pendulum and the rotational/disconnection path of the disconnecting pendulum. In comparing clips of Zito from early 2000 when he was throwing 89-90 mph to now, there are small but significant differences in his delivery. 在Zito的情况中我看见了同样的事情。 要发现这类的问题是很困难的，因为在大联盟这种层级的竞争强度中只要有一点微小的改 变就会造成球速大幅衰退，这让教练团很难发现问题的成因。此外，发现是一件事，修正 又是另一件事。 这里有两样工具可以让我们认识到身体在投球时的物理和体能状况—这两者的结合叫生物 力学。 从生理学的角度看，我找到了一个3D投球模拟软体可以让我们了解身体是怎麽投球的。要 做出这样的模拟系统，你必须先要知道投球过程的物理原理和投球过程中身体各部位的活 动。 "推球"是最常见也最不容易发现的投球问题。关於"推球"的另一种说法是"用力投球"。 "用力投球"的原因是在一连串的身体旋转过程中有不连贯的情形存在。造成这种现象的一 个常见原因是试着把放球点更往前延伸。这麽做会让身体的旋转减少并造成线性的收尾 (不连贯)。之前我有提到过，"南北"投手很容易有这方面的问题。 你可以是个成功的"南北"投手如果你有"东西"方式的旋转。但任何一点旋转方式的改变对 "南北"投手而言都是灾难。 当身体运动时各个旋转转轴不能相互配合时，"不连贯"就发生了。这个动画可以让我们了 解到什麽叫"不连贯"。 左手边这张是完全连贯的投球过程；右手边这张也几乎是完全连贯—除了在球出手前的那 一瞬间。 左手边的动作可以让出手瞬间的球速达到70 fps，右手边的动作则只能达到50 fps。 在投球过程中身体有几个重要的旋转转轴—前面的髋关节、上半身的旋转、肩膀的旋转。 这几个重要的旋转转轴能产生所谓"挥鞭般的"挥臂动作。 另一个重要的点是手臂的"弯曲"，手臂"弯曲"需要从肩膀到手的各个关节的配合。"弯曲" 的成因是肩膀旋转和身体下压产生动量的结果。这其中的关键是使各旋转中心良好配合， 保持身体各部位运动的稳定性。 这张图可以看出上面那两个动画的不同之处。 和Zito的投球动作比对一下，可以发现现在的Zito和以前的Zito投球上微小但影响深远的 不同之处。 --

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