Which statement best describes how net internal torque is determined?

Which statement best describes how net internal torque is determined?

• A. Gravity and friction
• B. A single agonist
• C. Passive ligaments
• D. Agonist and antagonist muscle groups

Answer: (D)

Torque about a joint comes from the forces of muscles that cross that joint. The muscles that are actively driving the movement (the agonists) create torque in one direction, while the opposing muscles (the antagonists) can produce torque in the opposite direction or resist the motion. The net internal torque is the sum of these internal moments—the balance between the opposing muscle activities. Gravity and friction are external influences and don’t establish the internal torque by themselves, and relying on a single agonist ignores how antagonists shape the actual rotation through coordinated or co-contracted activity. Passive ligaments can resist movement but don’t determine the primary net torque produced by muscle groups.

Torque about a joint comes from the forces of muscles that cross that joint. The muscles that are actively driving the movement (the agonists) create torque in one direction, while the opposing muscles (the antagonists) can produce torque in the opposite direction or resist the motion. The net internal torque is the sum of these internal moments—the balance between the opposing muscle activities. Gravity and friction are external influences and don’t establish the internal torque by themselves, and relying on a single agonist ignores how antagonists shape the actual rotation through coordinated or co-contracted activity. Passive ligaments can resist movement but don’t determine the primary net torque produced by muscle groups.