跳步犯规（Crow Hop）
跳步犯规是一种非法的投球动作，投手在初始蹬地之后重新落下轴心脚，实际上是重新起步，从而在距离或动能上获得不公平的优势。
合法的快投允许轴心脚沿地面拖行，目前的美国垒球协会（USA Softball，2022年）和NFHS规则也允许腾空——轴心脚离地——只要这只脚不重新落地再次蹬地；而跳步犯规是指脚重新落地，制造出一个更靠近本垒板的额外起步点。当投手试图借此产生额外球速时，这种动作经常被判罚，属于非法投球。理解这一点，对正在学习正确拖步力学的投手很重要——拖步是在保持脚与地面接触的同时产生驱动力的合法方式。
Practice dragging a chalk line with your pivot foot during dry mechanics drills. As a result, you can feel and see the legal contact path on every repetition.
Study slow-motion film of your own delivery in particular at the moment of push-off to confirm your foot maintains ground contact through the drag. This means small mechanics errors compound under game stress.
Example
投手在出手前抬起并重新落下轴心脚；裁判判定为非法投球，判给打者一个坏球。
How it shows up on video
From a side-angle video you will see the pivot foot lift clearly off the ground and land forward of its original position before the arm reaches the release point. This means a telltale second push rather than a continuous drag. The pitcher's hip will shift noticeably closer to the plate between the initial push and the second plant. Umpires watch for this by tracking the gap between the foot and the ground during the delivery.
Common mistakes
- Lifting the heel rather than dragging it, creating a micro-hop that umpires still call as illegal
- Confusing aggressive legal drive-and-drag with an illegal crow hop and becoming overly cautious, losing velocity
- Not practicing the legal drag motion in particular, defaulting to a jump as the body seeks more momentum
- Coaches missing the crow hop on slow-motion review because the foot barely leaves the ground
In SwingVantage Motion Lab
Motion Lab uses ground contact analysis on the pivot foot frame-by-frame to distinguish a legal drag from an illegal replant. This helps pitchers stay fast without the penalty.
Frequently asked questions
跳步犯规的处罚是什么？
会被判为非法投球：按目前规则，判给打者一个坏球，而自动让跑垒员推进一垒的规定在大多数规则体系中已不再适用。
投手仅靠合法的拖步还能产生高球速吗？
可以——一次强劲、合法的蹬地配合连续的拖步，能产生与跳步犯规相当的球速，同时保持在规则范围之内。
Related terms
Related guides & benchmarks
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