1. 0 Abstract The purpose of this experiment is to analyze the efficiency and technique of the students over arm volleyball serve after the use of biomechanical principles has been applied. In order to complete the experiment the student performed a pre and post test which was evaluated by the program Dartfish and a serving indicator test to assess the changes and improvements of the students technique and performance of the over arm serve. It was found that by applying the three biomechanical principles to the students serve the technique improved from the pre test to the post test as the serve became stronger, faster and longer. . 0 Introduction 2. 1 The intention of this report is to use the principles of biomechanics to analyze the efficiency and to improve the skill of the volley ball over-arm serve of a student from Mrs. Crellins year 11 PE class. Biomechanics is the field of study which makes use of the laws of physics and engineering concepts to describe motion of body segments, the forces which act upon them during activity, and the efficiency of movement. (Jacob’s university book).
The benefits of biomechanics are to develop new skills, detect errors in movement, improve safety, prevent injury, develop new equipment and form a basis of high quality and performance. The ultimate goal in sports biomechanics is the performance improvement of skills (source-howell). Biomechanics is applied in the volley ball serve by assisting the student to detect errors in the skill, improve safety and to effectively improve the skill itself by the way it is performed. 2. 2 There are four steps in biomechanical analysis which include identifying; the objective of the skill, the movement patterns, skill classification and the skill phases.
The objective of the over-arm volleyball serve is to get the ball over the net successfully at a fast, forceful, downward angle to ensure that it is harder for the opposition to return the ball back over the net. Movement patterns allow to identify the specific skills that fit within a given pattern. The movement pattern for the over-arm serve includes; throwing the ball in the air, striking it over the net and standing. Skill phases are the breaking down of the skill into meaningful phases, each of which may be quite different in terms of technique and the underlying biomechanical principles (Amezdroz et al. 004). In the volleyball serve the skill phase is identified as the toss (refer appendix…), bow and arrow (refer appendix…) and the strike follow-through (appendix…). The skill classification of the over-arm serve includes discrete, closed, non-locomotor, and gross. The skill is classified that way as it has a distinct beginning and end, uses the larger muscles of the body, is performed in a highly predictable environment and as it is manipulative skill that occurs on one spot. 2. 3
If biomechanical principles are applied to the students over-arm volleyball serve then the skill should improve as using the correct technique should make it hard, long and fast. 3. 0 Research Methodology 3. 1 There are three major principles of biomechanics that come into analysis when evaluating the technique of a skill. These three principles are force and momentum, inertia and levers and projectile motion. This background knowledge of biomechanical principles assists in the learning of the over-arm volleyball serve by applying the techniques to them for improvement.
Pre and post tests will both be performed with Dartfish being used to evaluate the video footage and a serving indicator to analyse the efficiency of the serve. 3. 2 Force and momentum can be broken down into three subcategories of: linear momentum, summing momentum and generating momentum. Though throughout the skill acquisition of the volleyball serve the concepts of summing and generating momentum were applied to assist in both the learning and improvement. The concepts of inertia and levers were also used during the learning stage of the serve.
There are three classes of levers and the volleyball serve is classified as a third class using the shoulder as the axis, muscles as the effort force and the ball as the resistance force (refer appendix__) and inertia refers to Newton’s Law of Inertia. The last biomechanical principle that was applied over the term of learning to improve the efficiency of the student’s volleyball serve technique was projectile motion. 3. 3 The program Dartfish is used to give a thorough analysis of the over-arm serve to assist in the evaluation of physical performance and biomechanics within the skill.
It is utilized to track movements of joints, the angle in which the ball has been hit, how high the ball has been thrown and to analyse the pre and post test and ideal server. 3. 4 The Indicator 1: Serving Performance Test is a used to see how much the student has improved over the time of the skill acquisition of the volleyball serve by comparing results from the pre and post test serving performance. The aim of this test is to objectively measure performance of the students over-arm serve.
The student performed six over-arm serves from any position on the volleyball baseline and each serve was scored objectively based on the landing position of the ball (refer appendix __) out of a possible five marks. Any serve hitting fixtures or landing out received no score. Individual serves were scored and the total score was then added to indicate a level of achievement (LoA). 4. 0 Statement of Findings/Results 4. 1 Using the Dartfish Program the students post and pre test of the serve was analyzed to view changes that may have occurred within the students techniques.
Many similarities and differences can be observed by looking at the two video performances and snapshots made from using Dartfish in Figure 1. 0 and 3. 0. By the changes evident in the two performances it is known that the biomechanical principles that have been applied to the serve have helped to improve the student’s performance and technique. It can be seen by comparing figures 1. 0 to 2. 0 that the students serve in the post test has acquired a larger optimum stretch as the body parts and muscles are all stretched to optimal lengths.
By doing this the students post test serve uses as many body parts as possible, each body segment makes it optimum contribution, has a larger range of motion and a greater amount of momentum and energy is being transfer from the arm swing to the ball (stabilization). This is why the post test serve is an improvement on the pre test as it achieves and applies maximum speed and strength into the serve. The major difference in the post test serve to the pre test serve is the use of the stabilizing arm (left arm).
In the post test the student uses the stabilizing arm to further speed up the rotation of the striking arm by bringing it into the chest quickly; this increases full body rotation as well as the speed of the rotation of the lever. During the pre test serve the student does bring the stabilizing arm into the chest but at a much slower rate, therefore, decreasing the speed of rotation. This improvement in the serve shows that by applying this biomechanical principle of inertia and levers to the serve the students serve was able to improve as it is the correct technique and makes the serve faster and harder.
Figures 1. 0 and 2. 0 show the similarities between the height and speed of release and contact of the ball between the pre and post test. In both tests the students striking arm was close to full length and had the same high ball toss. Howell says that this gives more time for the student to get from the skill phases of bow and arrow (refer appendix…) to alternating to a straight striking arm for follow through (refer appendix…), and contributes to get the optimal angle. The pre tests angle of release is closer to the ideal angle than the post tests angle.
Amezdroz says that the ideal angle of __ will create a lower and flatter flight path. This flight path is the correct technique to perform a serve as it will create it to be long, hard and fast as the biomechanical principle improves the performance. 4. 2 Using the Volleyball Serving Indicator Test (refer appendix__) the student was able to objectively measure the performance of her over arm volley ball serve by performing a pre, mid and post test of six serves scored on the landing position of the ball.
The total score of the student’s pre test that was performed was 8 points with a LoA of C and individual points of 2, 0, 2, 2, 0, 2. The results obtained from the mid test were 3, 0, 2, 3, 0, 2 with a total of 10 points and a LoA of C. The post test of the student results consisted of 4, 3, 3, 0, 2, 0 and had a LoA of C and total of 12. From the pre test results it can be seen that the student is at the beginning of the learning stage as she has not achieved a high number of points and has acquired two zeros which were obtained from the serves not making it over the net.
Looking at the results from the mid test show that the student has improved their serve but not improved in consistency which is made known by the result of the 0 points. Compared to the pre test it can be seen that the students has a better biomechanical correct serve as, as shown through the achievement of a 3 pointed serve, the angle of the serve was closer to the ideal angle of a serve. The achievement of a 4 pointed serve and multiple 3 pointed serves in the post test indicates that the student has again improved their performance.
Throughout all of the tests the student has not been very consistent in their serves as in each analysis has acquired two 0’s, these points have been a result of the student not being able to get the ball over the net. Comparing the results of each of the tests performed it can be observed that the post test was the best. Although it is an objective measure it can be seen that the application of biomechanical principles has indeed influenced the performance and results of the tests as well as accepting the hypothesis that if the principles are applied that the skill should improve by making it hard, long and fast.
An example that the serve has improved to become hard and long is the achievement of a 4 pointed serve (appendix __) which is located at the back of the court. 5. 0 Analysis and Evaluation 5. 1 Force and momentum relates to Newton’s Law of Acceleration, which states that, ‘any change in motion is directly proportional to the applied force and is made in the line of force’. Comparing the Ideal server (figure 4. 0) and the post test serve (figure 3. 0) shows that the student has aspects of the serve that she can improve on.
The ideal server has a greater optimum stretch and contribution of body segments, a greater range of motion, use of body segments and stabilization. The ideal servers serve is a lot more effective in the use of the range of motion compared to the students post test serve; this is represented in the longer lines of movements in figure 4. 0 to the shorter lines of movement in figure 3. 0. Powerpoint says that the greater the force required the more body parts must be used. Figure 4. portrays the larger amount of body parts the ideal server has used in the duration of her serve in relation to the smaller amount the students post test shows, this indicates that the students serve was not as powerful as the ideals. An alteration that could be made to improve the performance of the students over arm serve is to enhance the optimum stretch of the student’s body whilst serving. Newton’s Law of Inertia states, ‘A body will continue in it’s state of rest or uniform motion unless acted upon by an applied force’.
To further increase and enhance the students performance of the serve to become more like the ideal server the student should have a longer resistance arm within the duration of the serve. In figure 3. 0 the students resistance arm (left arm) can not be seen whereas in figure 4. 0 the ideal servers resistance arm is straight and in clear view. For the direction of the object to change completely to the direction of the new force applied, the new force must be much greater than the original force; otherwise the movement becomes a deflection (McGinnis, 2005).
A projectile is an object propelled through the air or water by an external force, in volleyball the ball is the projectile. By comparing figure 3. 0 to figure 4. 0 it can be perceived that the ideal server has a better angle, height and speed of release than the student does in the post test. By looking at the ideal servers serve it can be distinguished that she has a better angle of release at 28 degrees compared with the student’s angle of 41. 6 degrees. A modification that will enable for an efficient serve in the students over arm serve is to improve the angle of release so that it is close to the optimal angle of ___.
The ideal server gives herself a greater height and speed of release then the student does, this gives her a better chance of getting if over the net as Kimmet et al. says that the greater the height of release, the greater the horizontal distance and the greater the speed of release, the greater the range. 5. 2 The impact the three modifications have made on the success rate and performance of the students serve has been phenomenal. By applying the alterations to the serve the skill improved as by using the correct technique it became hard, long and fast.
Enhancing the students optimum stretch also enables for a larger range of motion and the optimum contribution of body segments as once the body is at its optimal stretch there is a larger range of motion for body segments such as the hitting arm to track to hit the ball. According to Amezdroz et al. (2004) the greater the optimum stretch of the body and muscles before striking the ball will enable the muscles to contract with maximum force. This will create a hard and long serve as the correct biomechanical technique is being used.
Performing the serve at a degree close to the ideal angle of __ will create a much lower and flatter flight path than the angle of 45 which is said to be the optimum angle for gaining horizontal distance says Reid et al. (1988). This correct biomechanical principle ties in with the hypothesis as using this technique will help to enhance the skill by making in flatter and longer. Howell (1999) says that by using a longer resistance arm during the serve it will increase the linear velocity of the impact. To further speed up the rotation of the striking arm, the opposite arm is brought into the chest in order to increase full body rotation.
Therefore by increasing the speed rotation of the lever, the rotational inertia of the body has been decreased and the serve is able to become much faster and harder. It can be seen by analyzing the impact of the proposed three modifications that the serve will improve as the student uses the right techniques to make her serve harder longer and faster. 5. 3 This experiment could be investigated further by using the thing where you put things on your body and it track your movement. 6. 0 Conclusion It can be depicted by the statement of findings and results that the hypothesis has been accepted.
The differences in the post test to pre test in serving indicator and Dartfish program analysis’ indicates that the student has improved in the performance of the post test. The compared pre and post tests illustrated that the student’s volleyball serve has improved by applying biomechanical principles as it encouraged the usage of the correct technique resulting in a hard, fast and long serve. 7. 0 Acknowledgements Any assistance the student was given over the term of completing the investigation came from Mrs. Crellin, Mrs. Mayfield and my partners Casey Bernard and Mariah Cumberlidge.