Abstract

This paper analyzes the activity of throwing a baseball. It compares the performance of an expert and novice thrower. Data was collected through high-speed videotaping and was then reviewed in slow motion to find projection angles and displacement. Using scientific equations, estimations were assigned to acceleration and velocity. By using this process it was found that the baseball was released at a shoulder angle of 237° and a shoulder velocity of –420° /s. The elbow angle was 126° and a elbow velocity of 2160° /s. The greatest shoulder velocity was 2580° /s recorded in frame 13, one frame after the indicated release of the ball while the greatest elbow velocity was 2220° /s in frame 6.

Introduction

Pedro Martinez, a professional baseball player for the Boston Red Sox, can throw a baseball over 98mph. Ken Griffey Jr., a professional baseball player for the Cincinnati Reds, can throw a baseball in the air from deep centerfield to home plate, a distance of over 350 feet. One may wonder how people can do such things or how it is even physically possible. To answer these questions, they should know there are several elements that make both these tasks possible and the understanding of displacement, velocity, acceleration, and projection angle are just a few of these elements that will help them have a better understanding of a baseball throw. Through careful research it is possible to estimate a player’s ability to throw a baseball. Everyone may not be a professional baseball pitcher or outfielder, but understanding the proper throwing motion, factors, and key elements that make up the overall activity, can highly increase any athlete’s ability to throw a baseball.

Review of Literature

Many professional athletes work on throwing a baseball with speed and velocity. Reading articles that deal with the mechanics of throwing a baseball can help them in achieving that goal. By learning the proper throwing techniques, players can achieve their best velocity and accuracy while reducing the risk of injury to their arm or body. Learning the proper throwing techniques when young also allows a player’s muscles and mind to develop the correct memory. Proper throwing can, therefore, become a good habit that will stay with players throughout their playing lives.

In a study by the American Sports Medicine Institute, 29 elite pitchers in healthy condition were picked to do this research. This research concentrated mostly on improving the qualitative understanding of pitching with the help of videography, and giving us a quantitative three-dimensional description of the upper limbs during the baseball pitch. The purpose was to do a series of studies that would improve the understanding of shoulder injuries such as subluxation, impingement, and rotator cuff strain that often occur in throwing athletes. The following three-dimensional picture helps give us a quantitative description of the upper limbs during a baseball pitch.

In an article by Sherry L. Werner, Biomechanics of the elbow during baseball pitching, the writer gave six phases in throwing a baseball. The phases are the windup, stride, arm cocking, arm acceleration, arm deceleration, and follow-through. In the windup phase the throwing hand leaves the glove and the front leg strides to the target. The stride phase begins soon as the hands separate and ends when the front foot contacts the mound. The elbow is reaching a flexion of 85 degrees by the time the foot is making contact with the ground. The cocking phase begins when the lead foot contacts the mound and ends when the arm is at a maximum external rotation. Arm acceleration is the amount of time the arm takes from the cocked position to release the ball to its target. In this phase the triceps, wrist flexor-pronator are very active in this phase. Arm deceleration begins when the ball is released and ends when the arm has reached a maximum internal rotation. Lastly, there is the follow-through phase. The follow-through phase begins when the arm reaches a maximum internal rotation and ends when the pitcher attains a balanced fielding position.

The articles Biomechanics of the elbow during baseball pitching and Biomechanics of pitching with emphasis upon shoulder Kinematics, also deal with movements and angles about the shoulder during a baseball pitch. The main movements include shoulder abduction, horizontal adduction, and external/internal rotation. All of these movements occur in about 0.145 seconds, which is the average time to release.

When going through all the different movements of the arm, elbow, shoulder, and wrist, injuries are a problem that every baseball pitcher is prone to getting sometime throughout his career. To prevent these injuries and to maximize performance, principles of biomechanics must be presented in overhead throwing. According to Mike Lamson, author of Proper Throwing Mechanics, in order to improve throwing and prevent injuries, correct footwork, balance, stride, weight transfer, arm cocking, arm acceleration, and follow-through are all very important aspects of throwing a baseball. In his journal, there are seven phases in throwing a baseball overhand instead of six. In the first phase the pivot foot is lifted and turned out at a 45° to a 90° . In the second phase the pivot foot and leg make their initial contact while directly under the whole body with the knee bent and the body balanced over the pivot foot and leg. In the third phase the left foot is lifted off the ground and extended at a distance approximately equal to the length of the individual’s leg. The fourth phase contributes approximately one-half of the total throwing velocity. This is determined by the transferring of the bodyweight from the back leg to the front leg while hip and torso rotation is occurring. In the fifth phase the elbow of the throwing arm will start forward and flex to at least 90° . In the sixth phase the arm is ready to accelerate towards the target. In this phase the shoulder and the chest are bending no more than 30° . The seventh phase is the follow-through. In this phase the head, shoulders, and chest will come forward approximately 45° to 60° .

Warming up properly is also a major factor in whether you are prone injuries. In addition, being in good shape and well conditioned prevents injury. Also, stretching and warming up the entire body, like the shoulders and arms, is necessary before actually starting to throw. The American Sports Medicine Institutes states, "Warm up to throw; don’t throw to warm-up." When warming up, start throwing slowly over a short distance and gradually increase velocity and distance. This warm-up period will vary with the individual, but will be typically ten to twenty minutes.

There are many different things involved with throwing a baseball properly, from the way a person throws the ball, to the way a person uses their legs. All are very important aspects of throwing a baseball, although, the most important thing to do is warm up before throwing. The muscles need to be warmed up. This lessens the chance of tearing or even straining your muscles.

Methods of Data Collection

In order to do a quantitative analysis of the baseball throw it was necessary to videotape the throw, plot the joint centers, and use linear and angular kinematics to calculate the results. First, the apparatus for videotaping was gathered. The materials included a video camera, a video tape, a meter stick, markers (tape) for joints, a baseball, and a subject to throw the baseball. Tape was placed around the right wrist, right elbow, right shoulder, and right hip joint of the thrower. These joints were needed to determine the elbow and shoulder angles. A black dot drawn on the tape represented the center of each joint. This was done in order to eliminate as much error as possible when plotting the dots. Next, tape was placed on the floor as a starting point for the throw. Then, in order to have a clearer picture, the person in charge of videotaping adjusted the shutter speed to 1/500 second. Once positioned, the zoom on the camera was adjusted in order to see the whole motion of the baseball throw as well as the departure of the ball a few frames after the release. The record button was then turned on and the camera recorded the throws from the right lateral side of the subject. A third member of the group held up a meter stick in the field of view for ten seconds. The meter stick was used as a reference for determining actual measurements of the distance between the points. Finally, after stretching and warming up briefly, the subject threw the regulation size baseball eight times off a regular wood gym floor while being recorded so that there was sufficient footage for later analysis.

After the videotaping was finished, the materials were collected and the videotape was viewed using a television and VCR. Two transparencies were fixed onto the television with clear tape—necessary so that data could be collected from the videotape. In order to solve the various velocities and accelerations in this lab, the researchers then needed to mark both ends of the meter stick onto the transparency as a reference point. The researchers then plotted the movement of each joint throughout each frame. The first frame plotted was the point of release of the ball followed by the next four frames of the ball after it left the subject’s hand. Starting at this point, the joint movements were then plotted one-by-one backwards for a total of fifteen frames. Each point (ball, wrist, elbow, shoulder, and hip) was marked with a different colored marker. Ten of those frames occurred before the point of release and four occurred after. Once all of the dots were plotted they were labeled by frame number (1, 2, 3…) according to what joint they represented. The transparency was then photocopied.

Once photocopies of the plotted baseball throw were made, the dots for each frame of the ball were connected to each other, one through fifteen. The corresponding number of each joint center was then connected in order to make angles. For example, all of the # 1’s were connected from wrist to elbow to shoulder to hip. The dot representing the ball was not connected to the stick figures. The elbow and shoulder angles were of interest for angular kinematics and the ball was of interest for the linear kinematics. The elbow and shoulder angles were measured with a protractor using the wrist and hip as reference points. In order to measure the angle of release for the ball a horizontal line was drawn parallel to the bottom of the paper, which was assumed to be parallel to the floor. These linear and angular kinematics equations were used to calculate the results for each of those to angles. The equations used include:

Linear Displacement d = p₂- p₁ Angular Displacement q = Ð 2 - Ð 1

Linear Velocity v = d / D t Angular Velocity w = q /D t

Linear Acceleration a = v₂-v₁/ D t Angular Acceleration µ = w₂- w₁ /D t
 

Results

Table 1: Ball at Release: Horizontal and Vertical Velocities.

Table 2: Elbow: Angular Displacement, Angular Velocity, and Angular Acceleration.

-176,400° /s² to 118,800° /s². At the point of release it was 61,200° /s².

Table 3: SHOULDER: Angular Displacement, Angular Velocity, and Angular Acceleration

Table 4: Ball: Linear Displacement, Velocity, anD Acceleration.

Discussion

According to research done in previous journal articles, the highest recorded pitching velocity was accomplished by Nolan Ryan during an actual game at 45.1 m/s.⁷ This compares to the average speed of college pitchers which range from 33.5-35.1 m/s.⁷ Table 3 shows the velocity of the ball after release for the individual in this particular study being only 21.538 m/s. However, the focus on this study was only to identify basic biomechanics so the individual did not attempt to reach his maximum potential in velocity.

It is interesting to note how the elbow angle stayed in the range of 90-95° until the subject externally rotated his right shoulder in order to achieve his maximum potential energy for the throw. While only one throw was analyzed in this lab, prior research has shown that faster ball velocity generated at release is related to greater external rotation of the shoulder at the beginning of the acceleration phase and greater trunk drive during delivery.⁸ Velocity and acceleration should be positive in this instance since greater shoulder and elbow angular velocities are most likely due to their greater forces and torque during the arm cocking and acceleration phases.³ Some ways athletes increase the velocity of a baseball is to use lighter baseballs. This is more evident in younger throwers however, as they do not have as much force and torque as adult throwers.

Some of the results are what were expected going into the lab setting. The elbow angular displacements were all positive, but did not consistently go in one direction throughout the throw due to the whipping action of the arm. Elbow velocity jumped around and acceleration became negative (directional change) during the follow-through phase. In Table 2 notice how the elbow angle is rapidly changing during the throw. The subject is a college catcher and needs to throw the baseball as quickly and accurately as possible. He brings the ball next to his ear prior to extending his arm for the release. This allows him to achieve a whip action that helps him throw the ball with more velocity and as a result has elbow angle fluctuation between frames. As a whole, the angle of the elbow increased as the subject extended his arm to release the baseball and continued throughout the follow-through phase (Frames 13-15) where the angle became almost 180° .

The angle of the shoulder joint gradually increased throughout the fifteen frames. It is interesting to note how in frame 6 the shoulder joint’s acceleration is 0 while in frames 7-9 is its highest velocities. This is at the same time that the elbow angles for the same frames are negative velocities indicating a directional change. The ball meanwhile is only starting to increase its velocity during this same time frame. Using this knowledge and assuming it is correct, it seems likely that the shoulder joint is handling more of the acceleration at this point of the baseball throw and the elbow is starting the whipping action which would explain the negative values.

The velocity of the ball at release does not make sense in this lab. Velocity at release should be greater than after it has been released due to gravity since we were throwing on a flat surface, but the velocity at frame 12 is 15.385 m/s, in frame 11 it is 17.949 m/s and 21.538 m/s directly after release. The velocity should instead be increasing each frame until after release. One reason for this, though, might be because the researchers plotted the dot for frame 11 wrong. It looks like it is too low on the transparency, which would cause the incorrect values. Another reason that the values might not be accurate for the release point is how the release point was not entirely visible on the videotape before the group transferred it onto the transparency. The release point is actually right before frame 12, but it couldn’t be seen on the videotape. The ball in frame 12 is actually an inch or two away from the hand, but this is the closest frame in which the release point could be determined. One way the researchers could have solved this problem was to have recorded the baseball throw at a higher shutter speed so less movement would have occurred between each frame. This would have made their angular displacements more accurate.

There is also the potential for more errors in this lab. The subject placed a small piece of white athletic tape over his right shoulder joint, right elbow, around his right wrist, and on the right side of his hip joint. The placing of the tape was not scientific, but gave a reference point so that the angles of each point of interest from frame to frame could be found. The motion of the throw was then played in the VCR backwards in order to limit interference with the picture. This method of conducting the experiment was to minimize error, but it is very hard to eliminate it altogether. Also, the placement of the dots that were used to measure each angle might be incorrect in some instances, as it is difficult to always know exactly where each point of interest has traveled on a VCR tape and this can affect values.

While this lab was entertaining there are some ways to make it more meaningful. One way would be to compare the baseball throw to something. The researchers in this lab did this earlier in the semester by comparing an expert throw to a novice throw. It might be a better idea if the researchers used this comparison to make theories about how velocities/accelerations differ between the two subjects, solve, and then compare the final results between both subjects and discuss what their hypothesis might be. Another idea that can be researched more is how using a lighter baseball might alter velocity because a person is able to create more torque and force. Some future suggestions to make this lab less error-prone would be for the group to use a higher speed shutter speed (1/500) on the camera and maybe a different camera angle. The group conducting this lab sometimes had trouble determining the exact angle of each joint and another camera angle would have been more work, but also would give them an option when it was difficult to determine a joint angle.

Conclusion

Even after given perfect descriptions of the motions involved with throwing a baseball, an athlete may still find this activity difficult. Much information is available to these athletes, but they will most likely still be amazed when a professional athlete fires a baseball at 98mph for a perfect strike, or gets the tying run at home plate with a bullet from the centerfield fence. People should now realize that it’s only a matter of displacement, velocity, acceleration, and projection angles.

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