The GCB is a specialty bar designed to move the load away from your center of gravity. As you squat down, the weights swing forward so that they are in front of your body. This pulls your torso forward and forces you to really engage your core and lower back. Essentially, it helps to simulate a shitty squat where your lean too far forward and have to try and save it. You can also see that it allowed me to put my hands in a position different from where I would normally hold a barbell.
The use of this bar and it's obvious efficacy caused me to wonder why more gyms didn't carry specialty bars. Their use has long been relegated to gyms specializing in the Westside Method of powerlifting training. They've begun to sneak their way into private facilities specializing in training athletes and in collegiate strength and conditioning facilities. At Boston University Strength and Conditioning, we have several axle's (non-rotating fat bars), a safety squat bar and a bunch of trap bars (most people wouldn't consider a trap bar 'specialty' as much as a necessity). What use do they have in commercial gyms, though?
Specialty bars have all been designed to change a particular lift in some fashion. This allows lifters to maintain a particular movement pattern (squat) while changing a specific aspect of that lift. A GCB brings the weight forward; a safety squat bar allows you to squat without holding onto the bar; a buffalo bar allows the lift to keep the same basic squat as he would with a straight bar but ease up some of the stress of having their humerus externally rotated and abducted. For a powerlifter, it means that exercises are being varied enough to prevent them from getting into a bad habit regarding their movement.
For gen pop clients, specialty bars will allow people to do movement patterns that they were previously unable to do. This is a good thing!
Obviously, the first answer is to correct the movement dysfunction that is prohibiting the from, say, bench pressing. However, a lot of gen-pop clients won't fully understand why they can't bench press. Furthermore, unless they intend to compete in a powerlifting meet they have no reason to be able to do a conventional bench press with a straight bar. While fixing their issues, you could easily have them benching with a multi-grip bar or a shoulder-saver bar; both of which can keep your clients shoulders in a healthy, pain-free range of motion. A fat bar, too, will help relieve some stress on the wrists while pressing.
Similarly, a trap bar can help someone with poor mobility do deadlifts with an elevated neutral grip, rather than loading someone anteriorly with their shoulder internally rotated.
The aforementioned safety squat bar is, I believe, as useful to a commercial gym as the trap bar. The big reason for this is the gawd-awful thoracic spine/shoulder mobility that the majority of the gym-going public possesses. Putting a bar on the backs of these people would be negligent and asking them to front squat would be like asking Beyonce to not be so damned bootylicious.
A safety squat bar allows people to load up their squat pattern without endangering their shoulders in any way. So, you're telling me that I can get a client stronger while keeping them as a safe as possible? I'm sold.
Why, then, aren't more bars like these available in commercial gyms? Honestly, because I think most commercial gyms aren't that concerned about strength. These bars cost extra money, and most owners/managers won't understand the need of bars like these. They are generally much more interested in increasing class attendance or getting new treadmills. You could have a multi-grip, safety squat and trap bar for $900, which is about equal to the cost of a personal training package. You could make all of your training clients better/stronger, and attract more people to train. The gym, if equipped with adequate trainers, would be able to make their money back on the bar in no time flat as well as increase profit.
These are not simply toys for meatheads, but tools for a good trainer to use to get the most significant and safe results possible for a client.
Have a great day, and when you go lift heavy shit implore the manager of your local gym to invest in their clients well-being by purchasing some specialty bars.