A closed-chain movement is a movement, with your feet in contact with the ground; an open-chain exercise is just the opposite. Most machines offer open-chain application.
The human body is a kinetic chain that requires balance and stability from top to bottom. Machines eliminate maximal recruitment of the core muscles we use when we are in an upright or standing position. We can only accommodate a closed-chain lift while we are standing. We eliminate the function of the core and the muscles of the lower extremities when we sit down. And never sit down during a lifting session!
Whenever you can do any movement in a standing or closed-chain, application, do it. Another key tip for all lifters: Exercises where your body moves through space are the most beneficial for core strength as well as balance. I used to tell my athletes that they must become the machines.
We will cover these lifts in an upcoming article, so stay tuned.