IB Sports, exercise and health science B.1.3.2 Types of Muscular Contractions and Coordinated Muscle Action Key Definitions

The agonist, or prime mover, is the muscle primarily responsible for generating force to initiate and execute movement.

An antagonist muscle works opposite to the agonist, lengthening to allow movement while providing control and stability.

Isotonic Concentric – A muscle contraction where the muscle shortens while generating force.

A fixator (stabilizer) muscle stabilizes a joint so that the agonist can work effectively.

Isokinetic – A muscle contraction where movement occurs at a constant speed with variable resistance.

Isometric – A muscle contraction where tension is produced without a change in muscle length.

Isotonic – A type of muscle contraction where the muscle changes length while producing force, including both concentric (shortening) and eccentric (lengthening) contractions.

Isotonic Eccentric – A muscle contraction where the muscle lengthens while controlling force.

The process where muscles develop tension and may change length to produce force

Reciprocal inhibition is the neuromuscular process where the contraction of an agonist muscle is accompanied by the relaxation of its antagonist muscle to allow smooth movement at a joint.

A synergist muscle assists the agonist by enhancing force production or stabilizing the movement.