US patent #7,037,243, granted on May 2, 2006 to Lester J. Clancy of Mansfield, Ohio, is for
An exercise apparatus is provided that simulates the effects of jumping rope, but does not utilize an actual rope. Two handles are provided similar in appearance to jump rope handles. At the end of the handle, where the rope would typically be, a donut-shaped enclosure is provided and mounted to the handle along its symmetrical axis. Inside of each donut-shaped enclosure, a weighted ball that rotates around a circular chamber within the enclosure. When rotated, the weighted balls generate rotational torque to simulate the use of a jump rope.
(Thanks to Mike Kasunic and numerous other investigators for bringing this to our attention.)