Although you can't use as much weight as you normally do with barbells, you can trigger a stronger growth response by stretching your pectoral muscles on eccentric part of the lift. (fitnessandpower.com)
Make sure to always perform the negative, eccentric part of the lift in a very slow and controlled manner, and allow for an equally slow and smooth transition to the positive, or concentric portion, but then lift the weight up explosively to recruit as many muscle fibers as possible. (fitnessandpower.com)
Lowered pull - ups are a great pull - up variation that emphasizes the eccentric part of the movement for maximum back hypertrophy. (fitnessandpower.com)