Modeling of muscle activity of the shoulder mechanism

In this paper we present our modeling approach for studying the role of the shoulder muscles in the bowling (swinging) of a ten pin bowling ball and the moments,  stresses and forces that are induced on the shoulder. Three experiments are conducted to obtain data on the positional relationship of the muscles in the shoulder, and the external moments from the ball and arm are compared to the moments that the muscles can create.  Then, a mathematical model for a six degree of freedom in the human arm is developed for a given dynamic trajectory. The mathematical model of human arm kinematics is based on the experimental evaluation of selective movements in the sagittal, frontal, and horizontal plane. The developed model contains six revolute degrees of freedom for positioning the wrist and represents a redundant mechanism where each joint is dedicated to a specific task.