Closed chain exercises are more beneficial for learning body control and increasing the amount of muscular activation during exercise. (weckmethod.com)
Pull - ups are a closed kinetic chain exercise, which means that you move your body through space while your hands in a fixed position. (fitnessandpower.com)
Critics say that open chain exercises like the leg extension can damage the knees and that even full depth squatting is safer. (verywellfit.com)