Hop

A hop is a spring in which take-off and landing occur on the same single leg, making it a strictly unilateral movement built on the jump pattern. Mechanically it leans on the stretch-shortening cycle: as the working leg contacts the ground it is briefly loaded and lengthened under tension, storing elastic energy in the muscle-tendon units — most notably the calf and Achilles complex — which is then released rapidly to re-project the body. Because a single limb must both absorb and return force, short ground-contact times and high reactive stiffness tend to characterise the action, with the ankle and foot behaving as the primary spring while the knee and hip contribute support and orientation. The nervous system coordinates this fast coupling of absorption and propulsion, and balance demands are pronounced because there is no second foot to share the task of stabilising the centre of mass on contact.

The hop appears across sport in many guises. In track and field it forms the first phase of the triple jump, where an athlete drives off one leg and returns to that same leg before continuing; in basketball it shows up in one-footed gathers and reactive adjustments near the rim; and in skating and dance it becomes a rhythmic, expressive element. Conditioning and agility contexts use repeated hops as a reactive drill, sometimes vertically for height and sometimes horizontally for distance, and everyday movement echoes it in games such as hopscotch. The shared thread is the same-leg take-off and landing and the reliance on elastic recoil, but the orientation, height, distance and rhythm shift substantially depending on whether the goal is to travel, to rebound quickly, or to hold a controlled single-leg finish.