A threshold-activated piston device with dampened response for use an aircraft seat, includes a chamber, a piston, a releasable fastener and a coupler, wherein the fastener is configured to release the piston for a stroke in response to an impact force that exceeds a predetermined threshold. The predetermined threshold may be set by a friction member, spring, a tension fastener, a check valve mechanism and/or a catch mechanism. Motion of the piston device resulting from the impact force imparted is dampened by conversion of kinetic energy into thermal energy. The method of energy conversion may be through, but not limited to, friction, viscous damping or velocity squared damping. The piston device may be configured for reuse in allowing the stroke to be reset. Additional fluid ports and/or a spring enables resetting of the stroke.