For reference, here is a link to a separate post on the foot hyperarch (HA) mechanism.
https://www.discussfastpitch.com/softball-pitching/30687-fixing-sprinters-posture-using-foot-hyperarch-mechanic.html#post423537
https://www.discussfastpitch.com/softball-pitching/30687-fixing-sprinters-posture-using-foot-hyperarch-mechanic.html#post423537
