The world of elite gymnastics has been well acquainted with the world of sports science for some time. This relationship is something that (ideally) serves the larger gymnastics community well, providing it with a sound, scientific basis for improving performance and implementing injury prevention measures. For example, there have been multiple studies that have examined the forces exerted on the body of a gymnast performing a giant swing on the high bar. As the performer moved through the bottom of the swing, the peak forces ranged from 4.27 to 9.2 times the gymnast’s bodyweight (which is a lot, by the way). The joint that does most of the absorbing and transmitting of this force is the shoulder.
One particular study—entitled A biomechanical study of shoulder pain in elite gymnasts by Cerulli, et al.—was looking at the giant swing. The researchers noted that as the gymnasts were passing through the bottom of the swing, EMG muscular activity was sometimes rather low. This got me thinking…
Your shoulder joint needs stability in order to perform effectively (say, when you’re flying, for example). To a certain extent, your shoulder has some built-in stability that comes from what we could call passive constraints. These are things like your labrum, the joint capsule and the bones themselves. They provide passive stability to the joint. And then there are the active constraints. These include most notably things like the muscles and tendons that make up the joint.
Ah lingo. Flying trapeze and circus are filled with it! And now we’ve got anatomy lingo to deal with…so, just in case you’re not sure:
Labrum: The shoulder joint is a ball and socket joint. The ball is the head of the humerus (your arm bone) and the socket is the glenoid (part of your shoulder blade). Imagine a golf ball on a tee. That’s a really shallow socket. To give the socket more depth—and thus provide more stability to the overall joint—there is a ring of fibrocartilage around the glenoid. That’s the labrum.
Joint capsule: The surfaces within the shoulder joint are covered with cartilage to make them smooth (and able to absorb some impacts). Surrounding the joint is a thin, fibrous membrane. It contains synovial fluid, which provides lubrication for movement and acts as an envelope of sorts, providing a degree of passive stability.
If as a flyer passes through the bottom of the swing, there is ‘low muscular activity’ (which, for the sake of clarity, is the opposite of being tight), this means that there is a tremendous amount of force being exerted on the passive contraints within the shoulder joint. With the muscles of the shoulder basically relaxed, the labrum and ligaments take the brunt of the force.
The labrum and ligaments will absorb the majority of the force…until they don’t. Lots of force combined with little support from the shoulder’s active constraints is a great recipe for a labrum tear. No one likes a labrum tear.
Can we apply this to flying?
The bottom of a giant corresponds roughly to the bottom of the flying trapeze swing—the part of the swing where you’re sweeping or breaking. There are likely going to be differences due to the fact that the high bar is fixed and the fly bar is not and these numbers will also likely vary based on movement timing and relative strength of the individual flyer. Anecdotally, I know a guy who put a load cell on the fly cables and took some measurements while swinging and throwing layouts. The peak forces through the bottom of a swing measured in the realm of 2.5 times bodyweight. At the moment of the break in a layout, the measurement came in at 750 lbs of force. If you do the math, this works out to be at least 4 times bodyweight, which fits in with the lower end of the range of findings for the giant swing. I recognize that one guy’s informal measurements do not a scientific study make, but given the dearth of studies that have focused on flying trapeze, let’s accept for the time being that the forces are similar.
On Dan Pope’s Fitness Pain Free blog, he suggested that a part of what might lead to a labrum tear in that moment is poor technique. Specifically, this means improper timing of muscular activation…and that’s a fancy way of saying the right muscles aren’t contracting at the right time…and it’s hard for those muscles to react and contract when they need to if you’re not tight (meaning activated and ready; at the risk of belaboring a point).
So what to do?
How to swing and stay healthy in the long term? Better yet, how to make your swing not only safe, but more effective and ultimately, higher?
Let’s take a moment to talk about your rotator cuff. Simply put, your rotator cuff is made up of four muscles. The tendons of those muscles form a cuff around your shoulder joint. Their job is to maintain the position of the humeral head within the glenoid (or socket). The trick here that most people don’t recognize is that the rotator cuff functions dynamically and reactively. That means your rotator cuff works by responding to the external forces applied to your shoulder to keep the head of the humerus in the appropriate position based on the position of your shoulder at any given time. Basically, your rotator cuff does its job on a moment-to-moment basis.
Yes: doing those rotator cuff strengthening exercises are great, but to really train your cuff to do its job, it needs something more. The fancy term is reactive neuromuscular training. This means you’ve got to train the cuff to react to external destabilizing forces because, for example, throughout the swing, the position of your humeral head is constantly changing and therefore, constantly needs to be (re-)positioned appropriately in order to maintain maximum stability and function within your shoulder.
An ounce of preparation…
My hope is that warming up before you get into the air already seems like a good idea to you because it gets your muscles warm and limber. Now let’s add another reason to warm up: it makes your muscles more responsive! Here are two specific activities you can add to your warm up that will specifically aid in switching on that brain-to-muscle connection with your rotator cuff.
There are your good old fashioned arm circles—and those are smart to begin with—and then there’s taking your arm circles up a notch. Specifically, building up to making tight, fast circles overhead challenges your rotator cuff muscles to do their job and keep your humeral head in position was your arms move.
Rhythmic Stabilizations (find a friend)
These are a great warm up exercise that will really get your brain-to-muscle connection firing! Remember, the point is not to fatigue your rotator cuff. Only do this for about fifteen seconds or less. And make sure your partner is being appropriately gentle—if you can hear the hand slapping your arm, that’s too much force.
These are two simple exercises that you can—and should—do before you fly. Every time. Your nervous system will be primed and ready to keep your shoulder optimally positioned throughout your swing. That means not only will you be protecting your shoulders, but you’ll also be better able to develop and transmit power through your shoulders. More useful and focused power means a better and higher swing…and who doesn’t like that idea?