Power racks and Smith machines are common exercise tools found in gyms. Initially appearing quite similar, they can both be used for exercises such as squats, bench presses and shoulder presses. There are, however, some distinct differences between power racks and Smith machines, and each has advantages and disadvantages.
Named after the gym owner who commissioned the original design, Rudy Smith, Smith machines use twin rods to guide a barbell so that it can travel only vertically. By positioning an exercise bench or standing between the uprights, you can perform a variety of exercises. Plates are loaded onto the bar ends to increase the load, and you can place safety stops on the guide rails so the bar won't descend below a predetermined point. Some Smith machines use selectorized weight stacks instead of weight plates for resistance, but these are less popular than those with the traditional design.
Sometimes called power cages, power racks consist of a study metal frame in which barbell free-weight exercises are performed. By adjusting horizontal bars within the sides of the rack, you can determine how far the barbell can be lowered. Power racks have no mechanical movement parts but merely provide a safe environment for performing free-weight exercises such as squats, dead lifts and bench presses.
Smith Machine Advantages
The guide rods of the Smith machine eliminate the need for you to balance the barbell, so you can focus exclusively on lifting the weight. The bar won't move forward, backward or sideways, but only up and down. If you get into difficulty, you merely twist the bar, and it will hook onto the frame. You then can let go mid-rep without the bar falling on you. The bar in the Smith machine is usually counterbalanced so that its weight is significantly reduced. This can be useful if you're unable to lift a standard 45-lb. barbell. You can use the Smith machine for a variety of exercises, although the fixed path of the bar means that some movements may have to be adapted.
Power Rack Advantages
Power racks allow you to lift heavy weights safely. By setting the horizontal bars to a specific height, you can ensure that if you should drop the weight, it will not come crashing down on you. The barbell is not restricted in any way, which means that exercises performed in a power rack are identical to those performed elsewhere. Power racks often have attachments for chin-ups and dips, so the power rack provides both exercise versatility and safety. Power racks can be purchased for as little as $300 for home and light commercial use.
Smith Machine Disadvantages
The fixed path of movement used in a Smith machine ensures that the bar will not deviate from its horizontal path. This means that exercises such as the squat, bench press and shoulder press, where the barbell would normally travel in a slight arc, will place extra stress on your joints. Because the need for balance between left and right limbs is removed when using a Smith machine, it's possible for one limb to end up doing more work. Some exercises cannot be safely performed in a Smith machine, reducing its versatility. The Smith machine also tends to be large and expensive.
Power Rack Disadvantages
Power racks require the use of a standard 45-lb. Olympic barbell, which may be too heavy for some exercisers. Power racks tend to be tall and can take up a lot of room, making them unsuitable for gyms with low ceilings or limited floor space. For safety, power racks should by fixed securely to the floor, which may be prohibitive. Although the safety rods ensure the bar will not drop below a predetermined level, there is no way to secure the bar mid-rep, unlike on the Smith machine.