What is the action at the shoulder joint during the incline dumbbell bench press when the pectoralis major is working eccentrically?

During the incline dumbbell bench press, when the pectoralis major is working eccentrically, the muscle engages to control the lowering of the weights. In this context, horizontal extension and flexion are the movements taking place at the shoulder joint.

When the pectoralis major is engaged eccentrically, it is doing so to resist the force of gravity as the arms move from an extended or elevated position to a more flexed position toward the body. The horizontal extension refers to the action of the arms moving outward and away from the midline of the body, which involves the shoulder joint opening up as the arms lower. In the inclined position, the pressing motion primarily involves flexing the shoulder while controlling the weight's descent through horizontal extension, allowing the pectoralis major to contract in a way that supports stability throughout the movement.

This process of eccentric contraction is crucial during the lowering phase of the press as it helps to maintain control and prevent the weights from dropping too quickly, which ensures proper form and safety. Therefore, understanding the biomechanics of how the pectoralis major functions during this specific exercise helps in appreciating its role and the correct identification of movements at the shoulder joint.