Requiring more stability in the shoulders and the midline, while also increasing depth, the ring push-up is significantly more difficult than traditional push-ups on the floor.

"Double-unders require the athlete to propel the body upward and lift the feet up to several inches from the ground while making small, fast circular movements with the wrists in order to execute multiple turns of the rope with each jump. They develop dynamic balance, speed, quickness, agility, coordination, concentration, and cardiorespiratory efficiency." —Buddy Lee, "Jump Rope Basics, Part 2" (adapted)