Systems, apparatuses, and methods for end effectors having an aperture are disclosed. An end effector may be driven by a reciprocating driver that drives the end effector in a reciprocating manner. The end effector may have an aperture therethrough and may be formed from a flexible high rebound material. When driven, the end effector may transfer energy from the reciprocating driver to a target treatment area on a recipient for therapeutic purposes. Energy may pass from the reciprocating driver and be temporarily stored within the end effector before being released and imparted to the target treatment area. The end effector may contract about the aperture and rebound to deliver the energy.