要伸展的那条腿应该放在躯干的后面并弯曲膝盖。

The leg to be stretched should be positioned behind your trunk with your knee bent.

《柯林斯英汉双解大词典》

这也就是说你的脖子和脊柱应该处于中正的位置，肩膀和躯干放松，膝盖弯曲呈90度角，双脚平放在地面上。

This means your neck and spine should be in a neutral position, shoulders and torso relaxed, knees bent at 90 degrees with both feet flat on the floor.

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因为力量源自地面，弯曲你的膝盖能让你的身体处于一个更易通过躯干，髋和肩部转动获得能量的绝佳位置。

Because force is generated with help from the ground, bending your knees places your body in better position to produce trunk, hip, and shoulder rotation.

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