eccentric muscle activation
Also referred to as pliometric, eccentric muscle activation is "the lengthening of stimulated muscle" (Lombardi & Piazzesi, 1990). In this phase, force is always generated against the direction of movement. The first references of its use originated in the late 1950's and early 1960's (Faulkner, 2003) and were in relation to the heart. Webster's New International Dictionary defines it as "not having the same center" (pg 812). It was not until modern years utilized as a movement description of skeletal muscle activation.