This exercise helps emphasize the contraction of the pecs (you get a much better squeeze when you both push up and against the pins) while reducing the involvement of the shoulders. The triceps are also more easily activated. But even more interesting is that by pushing against the rack you automatically engage the lats, which will help stabilize the shoulders.
Every lifter should engage his or her lats when bench pressing, but many can't do it (or can't keep them engaged) and as a result the shoulder is less stable and more prone to injury. The scrape the rack bench press solves that issue and gives you more pec stimulation, which means more muscle growth.
HOW TO DO IT
Start the bar off from safety pins/supports. (No, this won't work the same in a Smith machine.) If you have the square supports you'll have to press it from the pins to the little edge that's slightly higher; this is where the bar is starting on the video. If you're using metal rods as safety pins, which is ideal, you can start from the pins themselves.
Once the bar is in the starting position (as close to the chest as possible), either on the edge of the pin or on the pin itself, set up like you would in a regular bench press. Get your glutes and abs tight, squeeze both shoulder blades together, and engage the lats – which is easy if you press with about 25% force against the pins.
Press the barbell both up and against the posts. Normally we apply about 25% of our max force pushing against the posts. If the weight is too light during a set you can compensate by applying more force against the posts. By doing this you'll turn an easy set into a hard and effective one.
