"Although muscles produce linear forces, motions at joints are all rotary. The rotary torque is the product of muscle force and its moment arm. The moment arm can be defined as the distance from the insertion of the muscle (or tendon) to the axis of rotation. For example, in the graph below the axis of rotation is the center of the ankle joint. The moment arm of Achilles tendon is shown as the blue arrow. This moment arm becomes shorter when the foot is on the ground (left panel) than when the heel is raised during takeoff (right panel)."

Purpose: You will use this assignment to apply the course content on the angular kinematic motion to an example of softball pitching. "Although muscles produce linear forces, motions at joints are all rotary. The rotary torque is the product of muscle force and its moment arm. The moment arm can be defined as the distance from the insertion of the muscle (or tendon) to the axis of rotation. For example, in the graph below the axis of rotation is the center of the ankle joint. The moment arm of Achilles tendon is shown as the blue arrow. This moment arm becomes shorter when the foot is on the ground (left panel) than when the heel is raised during takeoff (right panel)."