The Psychology Behind Bending Your Knees

If you pop the tail using only your back foot without lifting your center of mass, your body begins to fall immediately afterward. It's like holding an object in your hand—if you suddenly move your hand away, the object has no choice but to fall. The problem is that making your body smaller while you're falling means absorbing the entire impact all at once. Your instincts recognize this as dangerous. To protect you, your body naturally tries to extend your legs to absorb the impact whenever it senses that you're falling. As explained in this Tip (Link), overcoming this instinct requires more than relying on your back foot—you must use your whole body to lift your center of mass.