A power rack is a piece of equipment that is used in weight lifting. It employs a slight deviation from the approach that the Smith machine uses in exercise. To understand the significance and use of a power rack, one has to first understand the function of the Smith machine. A Smith machine is a barbell rack in which the barbell itself is enclosed between a metal frame on each end of the barbell inside of where the plates are set. The Smith machine was designed to be able to give the weight lifter a greater sense of control and safety with the weight, because Smith machines feature bar catchers to protect the weight lifter from crushing his or her chest in the decline portion of the lift.
The Smith machine has a few shortcomings that the power rack was intended to improve. The power rack is basically an open metal cage, with four vertical beams positioned in a square and two horizontal bars on opposing sides of the square which can be placed at differing, but always equal, heights. The horizontal bars serve as the barbell catcher, so it is equal to the Smith machine in terms of its safety features.
The power rack is widely considered superior than the Smith machine because the barbell is not enclosed inside of a metal frame, which allows for the weight lifter to have a more natural lift motion. A more natural lift motion without the restraints of the enclosed frame of the Smith machine is important because weight lifters who are looking to increase their strength and lift more weight need to first become familiar with the weight before lifting the target in a full lift. A power rack can be used to familiarize the weight lifter with a weight more advanced than he or she is used to lifting because they can set the barbell catchers above their chest in a bench press for example, and just practice doing half of the regular motion of the lift. There is no risk of injuring oneself by dropping the barbell onto the chest.
The main lifts that can be accomplished on a power rack are chest and leg exercises, and more specifically, bench presses and squats. Both bench presses and squats at heavy weight require more safety precaution than a spotter might be able to provide, which is why the horizontal barbell catchers are such an important feature. A flat bench, which may or may not have the incline/decline feature, can be easily placed inside of the power rack to do bench presses. Power racks may also be used to exercise the abdominal muscles with the addition of ab straps onto the top of the cage.