The 1966 book Bionics: Nature's Ways for Man's Machines by Robert Wells has some great pictures of the "Man-Amplifier." Even after reading about it I'm still confused as to how this contraption helps lend greater strength to one's muscles.
This Man-Amplifier helps the pilot or astronaut encumbered by a clumsy and tiring space suit. Strapped to the man, it is a metal skeleton with electrical motors at important joints. These motors follow the man's body movements, operating when he moves, stopping when he stops - thereby lending greater strength to his muscles.