摘要
AthleanX 的 Jeff Cavaliere 认为，传统的坐式腿屈伸机对膝盖有害，原因在于其会对髌骨产生极大的压缩力。他提出了一种低滑轮绳索替代方案，训练相同的 knee extension 动作模式，同时保持双脚着地，从而降低关节压力并建立更具功能性的腿部力量。
要点
- 避免使用坐式腿屈伸机：该动作对髌骨产生的压缩力约为体重的 8 倍，长期训练会对膝关节健康造成损害。
- 双脚着地的动作更优越：腿部训练时保持脚踩地面，更贴近真实运动场景，并能减少有害的关节负荷。
- 低滑轮绳索替代方案：将绳索固定于踝关节，背向低滑轮后退行走，以更安全、更具功能性的方式复制腿屈伸动作。
- 每向后退一步 = 一次腿屈伸：每一步都涉及单腿膝关节伸展，与双腿器械训练相比，训练需求更高。
- 强调离心阶段（负向）：缓慢向配重组走回，控制离心收缩过程，这对 muscle hypertrophy 至关重要。
- 关节健康决定训练持续性：损伤膝盖、踝关节或肩膀的动作会迫使你中断训练，最终限制长期进步。
- 该动作可以使用较大重量，同时仍能保护膝关节，因此是可行的替代方案，而非退而求其次的选择。
动作详解
低滑轮绳索腿屈伸（行走式）
目标肌肉
- Quadriceps（主要肌群）
- 单腿稳定肌群
正确动作要领
- 将低滑轮绳索固定于一侧踝关节
- 面向绳索机，保持运动员低重心站姿
- 向后退步，每步均充分伸展膝关节
- 手臂保持放松——所有驱动力来自腿部
- 返回时，缓慢向配重组走回，控制离心阶段
- 在配重组落下前停止，以维持张力
常见错误
- 借助手臂惯性辅助动作
- 返回阶段过快（失去离心训练效果）
- 身体直立而非保持低位运动姿态
组数/次数
- 未明确说明，但每个方向均需完成多次动作；据指出该动作能迅速产生明显的燃烧感
相关概念
- knee extension
- compressive force
- muscle hypertrophy
- quadriceps training
- eccentric training
- functional movement
- joint health
- cable machine training
English Original 英文原文
Summary
Jeff Cavaliere of AthleanX argues that the traditional machine leg extension is damaging to the knees due to extreme compressive forces on the kneecap. He presents a low-pulley cable alternative that trains the same knee extension movement pattern while keeping the feet on the ground, reducing joint stress and building more functional leg strength.
Key Points
- Avoid the seated leg extension machine: The compressive force on the kneecap during the exercise is approximately 8 times your body weight, making it destructive to knee health over time.
- Feet-on-the-ground movements are superior: Keeping the feet planted during leg training more closely mirrors real-world athletic movement and reduces harmful joint loading.
- The low-pulley cable alternative replicates the leg extension movement in a safer, more functional way by attaching a cable at the ankle and walking backward from a low pulley.
- Each step backward = one leg extension: The movement involves single-leg knee extension with every step, increasing the training demand compared to a bilateral machine exercise.
- The negative (eccentric) phase is emphasized: Walking back toward the weight stack slowly controls the eccentric contraction, which is important for muscle hypertrophy.
- Joint health determines training consistency: Exercises that damage the knees, ankles, or shoulders force time out of the gym, ultimately limiting long-term progress.
- You can load this exercise heavily while still protecting the knees, making it a viable replacement rather than a regression.
Exercise Details
Low-Pulley Cable Leg Extension (Walking)
Target Muscles
- Quadriceps (primary)
- Single-leg stabilizers
Proper Form Cues
- Attach a low pulley cable to one ankle
- Set up in an athletic, low stance facing the cable machine
- Walk backward, fully extending the knee with each step
- Arms remain passive — all drive comes from the legs
- On the return, walk back slowly toward the weight stack, controlling the eccentric phase
- Stop just before the weight stack touches down to maintain tension
Common Mistakes to Avoid
- Using arm momentum to assist the movement
- Rushing the return phase (losing the eccentric benefit)
- Standing upright instead of maintaining a low athletic position
Sets/Reps
- Not explicitly stated, though multiple working reps per direction are performed; the exercise is noted to cause significant burn quickly
Mentioned Concepts
- knee extension
- compressive force
- muscle hypertrophy
- quadriceps training
- eccentric training
- functional movement
- joint health
- cable machine training