When you hook without turning your fist (fingers parallel to the ground), you have to tighten up your fist and your forearm to keep from hurting your wrist on impact. When you turn your fist(fingers facing you), your forearms and your wrists naturally tighten and it's easier to avoid pain to your wrists.
When you hook without turning your fist (fingers parallel to the ground), you have to tighten up your fist and your forearm to keep from hurting your wrist on impact. When you turn your fist(fingers facing you), your forearms and your wrists naturally tighten and it's easier to avoid pain to your wrists.