Which kick is specifically used in the butterfly stroke during swimming?

In the butterfly stroke, the specific kick used is the dolphin kick. This technique involves a simultaneous up-and-down motion of both legs, resembling the movement of a dolphin as it swims. As swimmers perform the butterfly stroke, they execute this kick in coordination with their arm strokes, which helps propel them through the water efficiently.

The dolphin kick is integral to maintaining rhythm and generating momentum in butterfly swimming and is distinct from other types of kicks used in different strokes. It plays a crucial role in the overall performance of the stroke, allowing for smoother transitions and sustained speed.

In contrast, the other kicks mentioned serve different purposes in different strokes. The freestyle kick, known as the flutter kick, involves alternating movement of the legs and is primarily used in the freestyle stroke. The flutter kick is more suited for maintaining buoyancy and balance in freestyle swimming, while the breaststroke kick includes a circular motion of the legs, which is unique to that stroke. Thus, the dolphin kick is the clear choice for the butterfly stroke.