The OSHA describes power grip as wrapping the fingers and the thumb around the object that you are holding.
Use power grips to hold and move objects around. It uses the hand and forearm muscles effectively and is less stressful than a pinch grasp. That's why you should use a one- or two-handed power grip whenever possible or needed.
It is recommended to use the power grip for many items, including bags, cans, and small boxes. It keeps you from dropping things, which can cause accidents, besides preventing you from twisting or harming your hands and wrists.
Source: The Occupational Safety and Health Administration: Guideline for Retail and Grocery Stores
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