螺旋球
Also known as: 螺旋球
螺旋球会朝同手打者内侧移动，变化方向与曲球相反，它来自出手时手腕向外甩动、手掌朝远离身体的方向翻转。
它是一个镜像动作：从右投手出手的球，会朝右打者方向移动，而不是远离她。手腕向外、以小指领先的旋转方式，在力学上与曲球正好相反，这使得它学起来别扭，也难以维持手臂健康。不过一旦掌握，它能顶住同手打者，并与它的对立面（曲球）搭配使用，产生毁灭性的效果，让投手在两个方向都拥有变化能力。
Master the curveball first and understand its wrist mechanics thoroughly before attempting the mirror image.
Use it selectively as a third horizontal option that reverses your existing break, which makes both far more effective by contrast.
Example
面对一名喜欢拉打的右打者，她把球起始于外角边缘，随后钻向内侧顶住打者的手部，逼出一次卡手的滚地球出局。
How it shows up on video
Watch for the hand turning away from the body, pinky leading, as the arm passes the hip. This means the reverse of the cross-body snap that produces break the other way. The ball will appear to tail back toward same-side hitters and can be confused with a drop ball until it misses inside rather than below. Hitters beaten by it show cramped elbows and contact near the hands.
Common mistakes
- Excessive outward rotation starting too early in the arm circle, creating arm stress and telegraphing the pitch
- Confusing the mechanics with a rise ball and accidentally adding backspin, producing a flat armside pitch
- Not matching the rep volume of the opposite break, which produces asymmetric forearm fatigue
- Hitters failing to tell the two apart and making identical adjustments when the movement is reversed
In SwingVantage Motion Lab
Motion Lab measures forearm rotation rate and release-point consistency to flag the early-rotation errors that raise injury risk on this delivery.
Frequently asked questions
这对手臂负担大吗？
如果以过度的前臂内旋或不良的力学动作投出，确实可能负担较大；正确的技术能把负担降到最低，但训练量的管理至关重要。
投手应该什么时候加入这个球种？
只有在掌握了快速球、变速球和曲球之后——它是一种高级的专门球种，通常在高中或大学阶段才会加入。
Related terms
Related guides & benchmarks
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