Negatives are great way to add more intensity into your workouts. They are preformed by controlling the tempo of the repetition and slowing down the lowering phase of the lift to an 3-5 second count.
Negatives are typically done after the primary work is compete for the main exercise. For example, if you are preforming 3-4 sets for a bench press, 1-2 sets of negatives will be done after all of the bench work is done.
By adding the negative sets, it causes the torn muscle to adapt, which will build bigger muscles and help you get stronger.
This will be a great way to end the set strong and blow out your muscles. They can be used often to really push you in the workout and overload the working muscle groups.
This is why at Atlanta Fitness Diva, we use negatives. As most of us are trying to build more muscles, we use them to overload the muscles a different way and push through plateaus at the gym.