for everyone from beginners to World's Strongest Man winners, such as Magnus Samuelsson, whose YouTube video clip closing the No. 4 Captains of Crush Gripper has been viewed over 2 million times. In 1991, IronMind began certifying people who could close its toughest grippers under official conditions, and it maintains lists of the people certified on the Captains of Crush No. 3, Captains of Crush No. 3.5 and Captains of Crush No. 4, Closing grippers of this strength level has been compared to crushing a raw potato in one's bare hand. In 2011, IronMind began certifying women who officially closed the Captains of Crush No. 2 Gripper. Use The user holds the gripper in one hand and squeezes the two handles together until they touch. Once touched, the handles are released and the movement is repeated. Variations of this basic movement include negatives [see below], and a variety of partial movements. For example, if the strength of the gripper is beyond that of the user, the user might apply maximum force, moving the handles as far as possible, even if the handles cannot be made to touch. Another partial movement involves using two hands to squeeze the handles within approximately 19 mm (3/4 inch) of each other, releasing one hand, and then using the other hand to make the handles of the gripper touch each other. Negatives involve starting the gripper handles touching and then resisting as the gripper opens up, in an eccentric contraction. Training Historically, users trained with grippers by doing high repetitions, but it has been argued that while this was necessary in the days before more challenging grippers were available, this is an inefficient way to increase strength, and that lower repetitions are preferred, consistent with other strength-training protocols Joe Kinney, the first man certified for closing the Captains of Crush No. 4 gripper, is credited with introducing the idea of negatives to gripper training. The idea of starting a gripper from the "deep set" position (approximately 19 mm space in between the handles) originated from an ebook that was inspired by Kinney's success, but then focused on training principles and techniques developed by the author, not Kinney. Randall Strossen has argued that the generally accepted principles of effective strength training apply to grippers, just as they do to any other movement. Performing strongman John Brookfield developed strap holds, the idea of hanging a small weight