Hyperactive definition, unusually or abnormally active: a company's hyperactive growth; the child's hyperactive imagination. See more.
muscle contraction. the process of force-generation in the fibres of any class of muscle, by the interaction of myosin head-groups in the thick filaments with actin molecules in one of the immediately neighbouring thin filaments.oncentric muscle contraction acceleration force generated within contracting agonist muscle tissue, by actin/myosin interaction; agonist muscle force overcomes antagonist muscle resistance, creating a net reduction in length of agonist muscle (see entry above).
shortening contraction a muscle contraction in which the ends of the muscle move closer together, as when a flexed limb is extended. tetanic contraction sustained muscular contraction without intervals of relaxation.tonic contraction tetanic c. twitch contraction twitch.ourglass contraction contraction of an organ, as the stomach or uterus, at or near the middle. isometric contraction muscle contraction without appreciable shortening or change in distance between its origin and insertion. Isotonic (A) and isometric (B) contraction.