Mr. and Mrs. Clark Bartram on the cover of Iron Man (2006)

As Clark mentions here on his site, changing the size of your grip can alter the neurological response of your muscles and nerves. By increasing the diameter of your grip, your body will respond differently from what it is normally accustomed to. Here, they lift sixty pounds for a minute. But as you will see, once the grip size in altered, a minute becomes a trying task indeed.