Which is where you will slowly
increase your
volume, or intensity (depending upon what phase of
training you are in), in order to
gradually improve your size or strength over a long period of time.
To put it simply, in these programs, you'll
gradually ramp up your
training volume by
increasing the number of sets you're doing (this is done on a weekly basis), while simulatenously DECREASING your rest periods in between sets, thus
increasing the overall density of your
training in a very deliberate fashion.