In the up phase of a bench press the shoulder joint is horizontally adducting caused by the concentric contraction of the pectoralis major, coracobrachialis, anterior deltoid and the short head of the biceps brachii. The scapula is initially moved into abduction by the concentric contraction of the serratus anterior and the pectoralis minor. The elbow joint is extended by the concentric contraction of the triceps and the anconeus.  In the down phase of the exercise the weight is lowered slowly with gravity. The muscles that concentrically contracted to lift the weight are the same muscles that are eccentrically contracting to lower the weight.