Types of Muscle Contraction

Co-Contraction

Occurs when the agonist contracts at the same time as the antagonist Ex: holding posture

Agonist

a muscle or group that causes the motion

Isometric Contraction

occurs when a muscle contracts, producing a force without changing the length of the muscle. No joint motion occurs Ex: Trying to pull your right hand out from under your right thigh

Stabilizer

A muscle or muscle group that supports a part and allows the agonist to work more efficiently Ex:gluteus medias

Eccentric Contraction (Isotonic)

As the joint moves, the muscle appears to lengthen as the origin and insertion move further away from each other. Can produce a greater force than concentric contractions. Often a "lowering motion" Ex: when putting a box down, the biceps brachii is eccentrically contracting to slow down gravity

Concentric Contraction (Isotonic)

As the joint moves, the muscle shortens and the origin and insertion move closer to each other Ex: when picking up a box your biceps brachii is concentrically contracting to move against gravity

Isokinetic Contraction

As the movement occurs, the resistance varies, but the speed remains the same Requires special equipment

Close Kinetic Chain

The distal segment is fixed and the proximal segment moves Ex: bench press, push up, squats

Open Kinetic Chain

The distal segment is free to move Ex:short arc quad, bicep curls

Prime Mover

an agonist, plays a significant part in causing the motion to occur Ex: in elbow extensions, the triceps is the prime mover

Isotonic Contraction

as the muscle contracts, the muscle length and joint angle change

Assisting Mover

assists in the production of the movement Ex: in elbow extensions, the anconeus is the assisting mover