What is the primary muscle used during the downward phase of a push-up?

During the downward phase of a push-up, the primary muscle utilized is the pectoralis major. This muscle is responsible for the movement of bringing the upper arms down towards the body, as one descends during the push-up. The pectoralis major is a large, fan-shaped muscle located in the chest, and its role is crucial in facilitating the pressing motion inherent in a push-up.

While other muscles, such as the triceps brachii and deltoids, also contribute to the movement, they function primarily to stabilize the position and assist the pectoralis major rather than being the primary movers. The triceps, for instance, are more engaged during the upward phase as they extend the elbows, while the deltoids provide support for shoulder movement but do not dominate the downward motion.

Overall, understanding the role of the pectoralis major during the downward phase highlights its importance in exercises involving horizontal adduction, such as push-ups. This knowledge can help inform training strategies to strengthen the chest muscle effectively.