抬腿
Also known as: 高抬腿, 膝盖上抬
抬腿是指在蓄力过程中前膝明显抬离地面，用以在跨步和挥棒发力之前建立额外的节奏感和储存能量——比点趾或无跨步方式风险更高、幅度更大的触发动作。
抬腿会把蓄力中正常的重心收拢动作夸大，让前膝明显抬离地面，有时甚至达到髋部高度或更高，然后腿再落回跨步位置。由于这个动作幅度更大、节奏感也比点趾更明显，打者常常觉得它能帮助自己更自然地与投手的投球动作同步，而更大的收拢动作也能为挥棒增加少量额外的储存能量。
代价是时机风险：抬腿需要经过的距离和涉及的动作环节比点趾或无跨步方式更多，这意味着在时间压力下可能出错的环节也更多。面对顶级球速或伪装出色的变速球时，大幅抬腿可能让打者没有足够时间把脚放下并开始挥棒——这正是许多打者在面对球速更快的投手时专门缩短或放弃抬腿动作、把完整的抬腿动作保留给更容易掌握时机的投手的原因。
抬腿本身并不天生就是力量动作——一些打者只是为了节奏感而做适度的抬膝，实际重心转移很小，而另一些打者则会把它与更积极的重心收拢结合起来。其动作机制价值取决于蓄力其余部分在做什么，而不是取决于膝盖本身抬得有多高。
Example
他在面对以速球为主的投手时使用完整的抬腿动作，但每当面对拥有出色变速球的投手时，都会把动作缩短为点趾。
Why it matters
抬腿是一种合理的节奏工具，但它会提高面对球速和迷惑性投球时的时机风险。SwingVantage会比较不同球种下的落地一致性，显示打者的抬腿动作在面对更快或更具迷惑性的投球时是否依然稳固。
How it shows up on video
The front knee lifts noticeably. This means often to or above hip height. This means before descending into the stride and landing. The overall motion takes visibly longer than a toe tap or a direct, no-stride load.
Common mistakes
- Keeping a full leg kick against velocity or deception that doesn't leave enough time to execute it
- Adding a leg kick for rhythm without addressing an underlying load timing problem it can't fix by itself
- Losing balance on the descent, which telegraphs into a rushed or lunging landing
Related terms
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