Kinesiology
To go into tiptoe, the ankle must be flexed to raise the heel off the ground. This requires the engagement of the calf muscle, along with various other muscles in the foot and shin to stabilize the joint. Even with this, the form is often less stable, requiring the engaging of muscles within the torso and a better sense of weight for the person, to stay balanced. There is generally some movement, even subtle, in the ankle, as holding it statically would make balance difficult, so it is the first to give.
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