In an isometric contraction, the muscle is contracted, but the length of the muscle does not change. In other words, you are holding the contraction in one spot. For the purpose of the TA2 program, you will want to do a mini-isometric contraction at the peak of the movement. You don’t have to pause at the top, just make sure you give it that extra little squeeze right as you reach the top. This is going to ensure that you get a peak contraction and activate as many muscle fibers as possible.