Skaters need to pull their limbs in at a force 1.5 times their body weight. That is why when skaters jump, their faces are never pretty!
Skaters take off at a 40 degree angle and rotate with a slight backward tilt, which is essential to landing in balance. If they do the rotations perfectly vertically, they will come down on the heel of their 2.9mm blade.
While running shoes have evolved considerably over the past two decades in providing cushioning and stability, the architecture of the skating boot has changed little in the past 100 years.
The key to doing a quad is snapping the arms and legs into position as tightly and quickly as possible. An elbow, a head or a free leg that sticks out will slow down rotation.