Concentric activation is associated with internal torque when the joint moves in which direction?

Concentric activation is associated with internal torque when the joint moves in which direction?

• A. In the direction of the muscle's action
• B. Opposite the muscle's action
• C. Only during swing
• D. Only in the direction of gravity

Answer: (A)

Concentric activation occurs when a muscle shortens while producing force, generating internal torque that rotates the joint in the same direction as the muscle’s pull. So the joint moves in the direction of the muscle’s action. If the joint moved opposite to the muscle’s action, the muscle would be lengthening under load (an eccentric situation) rather than shortening. Gravity or swing direction aren’t the defining factors; the key is that the muscle shortens and drives movement in its mounting direction.

Concentric activation occurs when a muscle shortens while producing force, generating internal torque that rotates the joint in the same direction as the muscle’s pull. So the joint moves in the direction of the muscle’s action. If the joint moved opposite to the muscle’s action, the muscle would be lengthening under load (an eccentric situation) rather than shortening. Gravity or swing direction aren’t the defining factors; the key is that the muscle shortens and drives movement in its mounting direction.