Tarheel Health Portal/Determining the Major Physiological Factors of Throwing a Disc

Ultimate is a relatively new sport that has started gaining a lot of traction in the public the last few years, especially among the youth and college age group. With every new sport, there are many fields and subjects that can be researched, including psychological (tactics) and physiological aspects. Ultimate is a game that is an amalgamation of sports such as soccer, football, and rugby, and such, the throwing or passing motion is an important part of the game for every player. You can often find someone throwing on the quad, usually struggling to get it to fly the way they want. The flight of the disc depends mostly on the angle of release and the amount of spin placed on it, while the wrist, arm, and shoulder are the main physiological factors. To determine which factors were the most important, experiments have been conducted that used high speed cameras and reflective markers to collect data about the joint kinematics. Determining the biomechanics of throwing will not only help to optimize the success rate of passes, but will also help realize any problems that could be detrimental to a thrower’s body. Each of these experiments used multiple volunteers and collected data from markers located on the wrist, elbow, and shoulder. Some of the experiments also indicated that there were specific stages of the throw in which the joints performed differently and included the wind-up or approach, the acceleration or the throw, and the follow through.

Wrist and Hand
The wrist is mostly considered to be a hinge joint although it has a little more freedom than a normal hinge joint would have. So the wrist is able to either flex (also called palmarflexion), which is when the wrist is bent towards the forearm and creating some angle, or extend (also called dorsiflexion), which is when the wrist is bent opposite the forearm. There is mainly one way to hold the disc for the backhand throw but there are two different ways one can throw the forehand throw, split forehand or closed forehand grip. For the forehand, it was found that the closed hand grip generated a larger velocity than the split hand grip and so the disc could be thrown with greater speed with no loss of accuracy or precision. The wrist for each throw goes through about 45 degrees of rotation. I believe that the wrist is one of the most important parts of the throwing motion because the wrist must be in a specific range of angles for the disc to fly correctly. Lorenz found that approximately half of the initial speed and nearly all of the spin is generated in the last tenth of a second before the release of the disc. The wrist, being the last part of the chain to move, thus plays an important part in creating the spin necessary for a disc to be stable and also travel farther.

Elbow and Forearm
The elbow is also a hinge joint and normally cannot go passed its 180 degree position. The forearm results in Saskawa and Sakurai’s experiment indicated that in order to throw the disc farther, skilled players started supinated at about 40 degrees and then pronated throughout the throw, while unskilled players started pronated at 20 degrees and then supinated for the throw. These results indicate that the forearm is an important characteristic of a skilled player compared to an unskilled player. The wrist goes through a large range of motion which shows that there is a large period of time that can affect the throw. Similarly to the wrist, the elbow goes through a large range of motion. What’s unique about the forearm is that it turns over past 0 degrees from supination to pronation for the forehand throw. This motion contributes to the creation of spin and keeping the disc relatively flat as well as keeping it on the same plane to limit air resistance.

Recommendations
There are many different characteristics of the body that make it possible to make the movements mentioned above. The entire kinetic chain in the arm is necessary to make the throws, but the lower body is also a very important part of making throws at different release points. Although these experiments cannot be entirely conclusive, it provides a large amount of insight into the biomechanics of the throwing of the flying disc. The range of motion of each joint is a good way to see whether it is a vital part of the throw because if it doesn’t need to move very much, then it is viable for the throw to be made without moving that joint. Unfortunately, there is not much research on this topic and there are some limitations to these experiments. The throws are being thrown at a comfortable height and since this is almost never the case when playing an actual game of ultimate, most of this information is void since a player must step out to throw around a player at a low level or to release the disc at a higher point than they normally would, which would affect how the entire arm operates to release the disc. However, it is the step in the right direction and this information can still be useful on a primordial level. The forearm throw is the one that is usually more difficult for beginners to learn and these studies may suggest that it is because beginners are being taught the wrong things to focus on. The other major limitation of the experiments is that only the skeletal system of the body is taken into account, while the muscular system is left almost entirely on the side. The muscular system provides the power for the disc and also connects to the bones through tendons, and so the body may place limitations on the bones and the joints based on the muscular-skeletal system. Ultimately, a player must learn not only how to optimize each of these ranges of motion, but to also learn how to do it safely.

Further Readings
A musculoskeletal model for the backhand frisbee throw by Hummel and Hubbard.

A Biomechanical Analysis of the Backhand Disc Golf Drive for Distance by Greenway.