Dynamic Constant External Resistance (1)
Here you see an individual doing a chest fly. In this case, again, you see no change in weight throughout the range in motion, so they had the dumbbells in their hands, that weight is remaining the same. You see a concentric, or shortening, phase as they're lifting their arms up above their body. As they lower the weight back down, that's the eccentric phase, that counts as one rep. And so this is a great example of dynamic constant external resistance.