Body movement. 1. A manner of grasping an object tightly, in a usually closed fist, between the palm and fingers. 2. To clutch, hold, or seize a bat, branch, club, or other object firmly with the hand.
Usage I: Our tight-fisted gestures given in anger, arousal, and fear employ the muscles and neural circuits of the power grip. Unlike its cerebral cousin--the precision grip--the power grip has its roots in a primitive grasping reflex, and often signals an emotional rather than a reasonable response.
Usage II: Holding objects tightly (e.g., steering wheels, posts, and handrails) is curiously pleasurable (perhaps as a holdover from our primate past and penchant for climbing trees; see PRIMATE BRAIN). Thus, power-gripping sports such as baseball, tennis, and golf are very popular today (see BRANCH SUBSTITUTE).
Culture. In Syria, clenching both hands in power grips, and raising them together over the midriff, with the thumbs positioned outward--as if stretching a rope--means, "I will strangle you" (Morris 1994:74).
Embryology. "A newborn infant has a grasp and a reaching reflex. He will automatically close his fingers tightly around any object placed in the palm of his hand" (Chase and Rubin 1979:177).
Evolution. The power grip originated as a primate adaptation for climbing.
Neuro-notes. In grasping a racket or a club, sensory feedback to the motor cortex may unconsciously tighten our grip. Stimulated by grasping, pressure-sensitive tactile receptors cause further excitement and contraction of muscles to unwittingly increase the tightness of our grip.
Drawing of "Showing My Nonverbal Side" by my son Aaron Huffman (copyright 2012 by Aaron M. Huffman)