Eccentric contraction- a contraction in which the muscle lengthens in an attempt to control the motion occurring at the joints that it crosses, characterized by the force of gravity or applied resistance being greater than the contractile force
Concentric contraction- a contraction in which there is a shortening of the muscle that causes motion to occur at the joints in crosses
Agonist- A muscle or muscle group that is described as being primarily responsible for a specific joint movement when contracting
Synergist- Muscle that assist in the action of the agonists but are not primarily responsible for the action, know as guiding muscle, they assist in refined movement and rule out undesired motions
Antagonist- A muscle or muscle group that counteracts or opposes the contraction of another muscle or muscle group.