What is the joint action during eccentric phase of a biceps curl?

During eccentric phase of the biceps curl, there is a joint action between the biceps and the triceps. The triceps performs an agonistic action, contracting concentrically to extend the elbow and lower the weight, while the biceps perform an antagonistic action, contracting eccentrically to resist the rapid lengthening of the muscle and slow down the movement. This eccentric contraction works to control the speed of the weight and prevent it from dropping quickly