Is a press up concentric eccentric or isometric?

A press-up (or push-up) involves both concentric and eccentric muscle contractions. During the upward phase (pushing away from the ground), the muscles in the chest, shoulders, and triceps contract concentrically. Conversely, during the downward phase (lowering the body), these muscles lengthen and contract eccentrically as they control the descent. There is no isometric phase involved in a standard press-up unless you hold a position at a specific point in the movement.