Which process allows movement to occur by relaxing the antagonist while the agonist contracts?

Which process allows movement to occur by relaxing the antagonist while the agonist contracts?

• A. Reciprocal inhibition
• B. Co-contraction
• C. Stabilization
• D. Isometric contraction

Answer: (A)

Reciprocal inhibition is the mechanism that allows movement by relaxing the opposite muscle when one muscle contracts. When the agonist contracts, interneurons in the spinal cord inhibit the motor neurons to the antagonist, reducing its activity so it doesn’t oppose the movement. For example, bending the elbow by contracting the biceps requires the triceps to relax. If both muscles contracted at the same time (co-contraction), the joint would stiffen and movement would be resisted. Stabilization focuses on keeping the joint steady rather than permitting movement, and isometric contraction involves generating force without a change in muscle length, so it doesn’t produce movement.

Reciprocal inhibition is the mechanism that allows movement by relaxing the opposite muscle when one muscle contracts. When the agonist contracts, interneurons in the spinal cord inhibit the motor neurons to the antagonist, reducing its activity so it doesn’t oppose the movement. For example, bending the elbow by contracting the biceps requires the triceps to relax. If both muscles contracted at the same time (co-contraction), the joint would stiffen and movement would be resisted. Stabilization focuses on keeping the joint steady rather than permitting movement, and isometric contraction involves generating force without a change in muscle length, so it doesn’t produce movement.