Eccentric Contraction

Eccentric Muscle Action Improperly termed "eccentric contraction," because the muscle does not actually contract, eccentric muscle action is the lengthening of the muscle while the contractile units are resisting the lengthening of the muscle with force production less than the resisting force. Force production in eccentric muscle action can be as much as 120 percent of the force production of the same muscles in concentric muscle action.