Strength curves
In every exercise we perform there are strength curves. Strength curves are certain points of a exercise in which the level of difficulty increase or decrease. To give a example of strength curves in a exercise im going to use the pull up. The exercise is the hardest at the top and the bottom. At the top its difficult to concentrate on not just pulling up but actually squeezing and contracting the lats at the top and then slowly(as slow as possible) descending all the way down into the stretch position. At the bottom your strength is at its most vulnerable point. You have deadweight hanging motionlessly and to come back up you have to concentrate on pulling with your lats symmetrically and not using any biceps or momentum to assist you. Every exercise has these variables. The way we grow better and get stronger is to get stronger in these areas when its most difficult. The more challenging it is the more of a benefit you will get from it.