Want to land softly/Want to avoid hurting my joints
Mechanism / Why It Happens
If your knees or lower back hurt, it may be because the way you move causes force to concentrate in those areas.
You may have seen an impact absorption test by an insole company. If you drop one egg onto an insole, the egg doesn't break, but as soon as you stack two eggs, they break. This is because the insole may slow down the falling speed of the bottom egg, but the top egg continues its downward motion, causing it to crush the egg below. This demonstrates that you need to use your whole body to absorb the impact of landing. If you straighten your knees when you land, for example, the impact will concentrate on your joints, just like with the eggs.
What to Do
Use your whole body to absorb the impact.
In physics, forces—including those generated when you land—cannot simply disappear; they must always
