Examining the Differences in Kinematics between a Free Throw and Three point Shot PDF

Preview

Summary

READINGS...

Description

EXS204

Biomechanics I

Examining the Differences in Kinematics between a Free Throw and Three-point Shot

Muktar Abdi 32740455 Lee Campbell

32566369

Braiden Clarke

32855052

Kabir Ebrahimi

32748821

Shakkya Jayawickrema

Murdoch University

32226906

1 EXS204

Biomechanics I

Introduction The main aim of basketball is to get a ball through a hoop. This can be achieved through various forms of shots. The skillset of shooting is very important to achieve this. There are various factors that can influence the accuracy of a successful shot (1). Shooting is the most important aspect of playing basketball, scoring is done through this method, and is the most frequent technique used in playing basketball. Basketball, similar to other sports involves decision making, which could impact on the result of the game. The most fundamental decisions in basketball are: when, where and how take a shot ranging from a free throw to a three-point shot (2). Through the years there have been many variations on the different shooting techniques. Including the difference in a free throw shot and a three-point shot (3). Because the target remains the same, the ring, the same height off the ground and the same width and length, the same person taking a shot from anywhere on the court is going to exactly the same target. So when comparing free throw shot as the close shot to a three point shot as the distance shot, there will be a change in kinematics and projection angles to compensate for the increase in distance (3). By studying the difference in kinematics, projection angles and release height between the two shots the ideal shooting technique can be established. By increasing the distance of the shot the player will have to adjust for the difference in accuracy and the power requirements of the shot (4). Various factors can influence the trajectory of a ball. These are release velocity, release height and release angle. Some studies suggest that when shooting the ball from a free throw, the release angle and release height of the ball will increase whereas the release velocity will decreases (5). The relationship between release angle and height is a vital one, because as soon as the player gets further away from the ring those to components will decrease, but the release velocity of the ball increases (6). In order to maintain shooting accuracy an adjustment at different distances will require an adjustment in the release angle to reduce spatial restraints of the basketball hoop (4). The aim of this study was to compare the differences in kinematic measures between a free throw shot and a three-point shot. It is hypothesized that the release angle and release height will decrease as you progress from a free throw to a three-point shot whereas the release velocity will increase.

Murdoch University

2 EXS204

Biomechanics I

Methods Participants The participants of this movement analysis project are five sport science students. Implied consent was given from each participant prior to setting up this movement analysis experiment. Four of these participants are right handed and one of them is left handed. Each of the participants will be required to wear a sleeveless shirt in order to prevent the obscuring of the arm as each participant engages in their free throw and three-point shot trials.

Procedure In this movement analysis project several pieces of equipment will be used to ensure that the movement of each participant is analyzed accurately. The movement analysis will take place in an indoor basketball court to make sure any environmental influences on the basketball shots are reduced such as wind and lighting from the sun. The Sony camera that will be used to record the movement will then be placed on a tripod stand to prevent any movement as well as any vibrations which could alter the motion capture. Since both the three-point shot and free throw shot are not high velocity movements, the camera will be set to record the movement at 50 Hz = 25 frames. A 1-meter calibration stick will be used for the purpose of the kinovea program to acknowledge that the length of 1-meter long. This program will later be used to analyses the motion capture. The basketball that will be used will be a standard size 7 ball and will be shot at a standard 3m basketball ring. Once the environment is set accordingly to the movement analysis, the participants will be allowed to warm up and engage in practice trials which include 5 practice free throws and 5 three-point shots to become familiar with the motion of shooting a basketball shot. The free throw is 4.57m away from the basket while the three-point shot is 6.02m (7). A reflective marker was placed in the centre of the mass of the basketball. This was determined by measuring the diameter of the ball from the two widest points and placing the maker at the halfway point. A maker was also placed on the base of the 5th metacarpal, styloid process of the ulna and the lateral epicondyle of the humerus to determine the angle of the wrist. The camera will be placed 7.26m away, which is the sideline of a basketball court (7), perpendicular to the sagittal plane of motion, which will be facing the dominant side of each participant.

Data analysis To determine release velocities the first 5 frames after the release of the ball will be recorded on kinovea and calculate the resultant displacement of the COM of the ball through its vertical and horizontal displacement. Release height was determined to be the vertical displacement between the COM of the ball and the ground. Release angle was calculated by measuring the angle between the vertical and horizontal displacement of the ball’s COM over 5 frames after ball release.

Murdoch University

3 EXS204

Biomechanics I

Each participant will have 5 trials each for a free throw and three-point shot. After each participant has completed their 5 trials for both shots we will find the average release angle, release height and release velocity for each participant’s free throw and three-point shot. We will then compare them with the other participant’s average results.

Results It was found that the average release velocity of the 5 participants for the free throw was 6.85 m/s whereas the average release velocity of the three-point throw was 8.18 m/s. This can be seen by referring to table 1.

Participant 1

Participant 2

Participant 3

Participant 4

Free Throw 7.01ms-1 6.99ms-1 6.85ms-1 6.73ms-1 average(m/s) Three-point 7.97ms-1 8.06ms-1 8.21ms-1 8.73ms-1 throw average(m/s) Table 1: average release velocity of the free throw and three-point throw

Participant 5

6.66ms-1

Average

6.85ms1

7.95ms-1

8.18ms1

For the release height it was found that the average difference in in the release height of the free throw and three-point shot of the 5 participants was -0.026m. This can be seen by referring to table 2.

Average difference in release height

meters

Participant 1

-0.036

Participant 2

-0.12

Participant 3

-0.004

Participant 4

-0.022

Participant 5

0.052 -0.026

Average

Table 2: average difference in release height between the free throw and three-point shot Murdoch University

4 EXS204

Biomechanics I

For the ball release angle it was found that the average release angle of the ball for the free throw was 49.09 degrees whereas the average release ball angle for the three-point throw was 50.64 degrees. This can be seen by referring to table 3.

Participant 1

Participant 2

Participant Participan 3 t4

Participant 5

Average free throw (deg)

51.232

46.484

53.62

50.852

43.264

49.0904

Average threepoint (deg)

53.214

50.722

49.086

52.614

47.59

50.6452

Table 3: Average ball release angle for free throw and three-point throw

For the wrist release angle it was done in two parts. The first part was the average wrist angle of the preparation phase for both the free throw and three-point throw. This was the initial stage of the throw known as the countermovement phase. The second part was the average wrist angle of the ball release phase. For the preparation phase of the free throw the average wrist angle was 161.32 degrees whereas the average wrist angle for the three-point throw was 161.04 degrees. The average wrist angle during the ball release phase for the free throw was 156.88 degrees in comparison to the average wrist angle of the three-point throw during the ball release phase was 154.36 degrees. This can be seen further by referring to table 4.

Average wrist angle of the free throw preparation phase

161.32o

Average wrist angle of the three-point throw preparation phase

161.04o

Average wrist angle of the free throw ball release phase

156.88o

Average wrist angle of the three-point throw ball release phase

154.36o

Table 4: average wrist release angle of free throw and three-point throw in the preparation and release phase

Murdoch University

5 EXS204

Biomechanics I

Discussion The results collected in this experiment supported our hypothesis to an extent. It was stated that as you progress from a free throw to a three-point shot the release angle and release height would decrease but the release velocity would increase. The average release height and release velocity were the only two variables that agreed with the hypothesis and was also congruent with pre-existing (4, 5, 8, 9) literature whereas the average release height falsified the hypothesis and contradicted the pre-existing literature on this topic. When you progress from a free throw to a three-point throw it results in a decrease in release height because of the requirement of an increase in velocity to move the basketball over a longer trajectory flight path for the ball to reach the basket (4). The relationship between the decrease in release height and the increase in velocity to carry the ball to the basket has been known to result in a decrease in the accuracy of the basketball shot (4). Only four participants had a decrease in there release height because they released the ball before they could achieve their maximum jump height which could be as a result of the participant being novices (8). Basketball shots that are taken from the free throw line, which is closer to the basket was found to cause the release of the ball to be timed to be closer to the greatest jump height, hence it can be assumed that shots that are taken in close proximity to the basket presented greater amount of stability, less distance travelled by the ball and also a decrease in the demand of being able to generate great amounts of impulse in order to propel the basketball when it is released from each participants dominant shooting arm (9). Increase in distance and an increase in release velocity were found to be directly proportionate. As each participant engaged in their three-point throw trials the concept of speed accuracy trade off was clearly visible meaning that the increase in distance between a free throw and a three point resulted in an increase release velocity which lead to a decrease in the accuracy level therefore the optimal strategy would be to release the ball at a minimum velocity in order to increase the accuracy of the shot and maximise the chances of making the shot (4). The increase in the average release velocity is a result of the ability of each participant to reuse the energy that they have created when they jumped to be transferred into their arms in order to achieve the optimal level of impulse in order to propel the ball to the basket (5). This technique of transferring the initial energy from the jump take off to the arms is common among novice players which the participants are and from further increase in distance from the basket (8). Regarding this technique of finding and applying the optimal impulse technique by releasing the ball at areas closer to the greatest velocity of the ball has been linked to the decrease in the accuracy of the shots which explains why the shooting accuracy diminishes as the shooting distance increases (9). The average release angle of the ball was found to have slightly increased as the participants progressed from a free throw to a three-point throw which is the opposite of what the preexisting literature states and therefore falsifying the hypothesis. The main reason for this was Murdoch University

6 EXS204

Biomechanics I

that the participants were novices and have adopted a simple strategy to deal with the increase in shot distance. Due to being novices the participants adjusted the release angle according to the increase in distance from a free throw to a three-point throw to be closer to the Y component, in other words they were focusing on throwing the ball up in the vertical direction rather than horizontally to increase the time of flight of the ball so it could reach the basket. Shooting the basketball in a vertical direction would introduce the most amount of errors because when the ball is released it observes the shape of the basket rim as being in the shape of a circle but from closer distances such as a free throw the shape of the basket rim becomes increasingly oval, except up to the point where the diameter of the basketball is bigger than the diameter of the basketball rim (10). Several other elements which the participants lacked in which could have contributed to the increase in average release angle could be several aspects which fall under the category of being a novice such as the timing, being able to pick up on advanced cues to position yourself accordingly and the positioning of the legs in accordance to each participant dominant shooting arm. These are all elements which can be improved overtime with practice. There were several limitations found in this experiment. The most common one was the ability to capture the center of mass of the basketball during the data collection. This was because when the basketball was thrown the marker would not stay in the center of mass in relation to the camera. So the maker would look like it was travelling in a circle with the rotation of the ball. This was overcome by using kinovea, after the calibration stick, the distance tool was used to measure the diameter of the basketball from the two widest points. From there the midpoint was used as the center of mass to calculate the height of the ball when released from the hand to five frames after that point. The strength of using the center of mass of the basketball was that the height was able to be found as well as the angle of the ball after release in addition to the velocity of the ball. Another limitation was doing the trials without recording the accuracy of the shots. By recording the accuracy of the shots, the results could have been able to determine which kinematics would be best suited towards each shot. As well as being able to see if there is a trade off with the results that were more consistent, were more accurate. The data collection could have been done indoors rather than outdoors, so it takes away extrinsic factors such as the wind due to it having a huge effect in terms of the balls flight path. Therefore having an effect on the angles being different each time with wind, the participant might get affect by the extrinsic factor and the shot changing i.e. more power when shooter is throwing into the wind. Indoor courts were not available at the time of data collection. The participants that took part in this study were only novices, so the changes are possible reason would be the angles changing as they do not have a consistent shot. Experts meanwhile would have a more consistent shooting pattern and provide better consistency in terms of changes occurring in both the free throw and the three-point shots.Indeed, aside from the results that were observed throughout the current study, there are still many questions that remained unanswered, and most important ones are from a coaching perspective. For example what strategy could be considered in a court position when conducting a free throw shot over a three-point shot? And that is how different shots will be varying from a position on the basketball court (11).

Murdoch University

7 EXS204

Biomechanics I

The results show a decrease in release angle in three-point shots from this study, something that coaches should be aware of and are able to develop a consistent movement pattern. From the coach’s perspectives to improve these shots, they should consider new types of drills on the court so their basketball players are able to enhance the shot accuracy performance (12). This and the extent of the effects outlined above are subjects of further research.

Murdoch University

8 EXS204

Biomechanics I

Reference list 1. Užičanin E, Pojskić H, Šeparović V. reliability and factorial validity of basketball shooting accuracy tests.Sport SPA. 2011: 8(1): 25-32 2. HAY, J. G. 1994, The Biomechanics of Sports Techniques (Englewood CliVs, NJ: Prentice-Hall). 3. Huston R, Grau C. Basketball shooting strategies – the free throw, direct shot and lay up. Sports Engeineering 2003; 6: 49-64 4. Hugo V, Okazaki A, Luiz A, Rodack F. Increased distance of shooting on basketball jump shot. J Sports Sci Med. 2012; 11(2): 231-237 5. Elliott, B. (1992). A kinematic comparison of the male and female two-point and three-point jump shots in basketball. Australian Journal of Science and Medicine in Sport, 24, 111-117. 6. Brancazio, P.J. (1981). Physics of basketball. American Journal of Physics, 49, 356-365. 7. Standard Measurement in Sport. Fact Monster. 2016. Available from:

http://www.factmonster.com/ipka/A0113430.html 8. Elliott B.C.(1992) A kinematic comparison of the male and female two-point and three-point jump shots in basketball. The Australian Journal of Science and Medicine 24(4), 111-118 9. Knudson D. Biomechanics of the Basketball Jump Shot—Six Key Teaching Points. Journal of Physical Education, Recreation & Dance. 1993;64 (2):67-73. 10. Miller S, Bartlett R. The effects of increased distance on basketball shooting kinematics. InISBS-Conference Proceedings Archive 1992 (Vol. 1, No. 1). 11. F.J. Rojas, M. Cepero, A. Ona, M. Gutierrez. Kinematic adjustments in the basketball jump shot against an opponent. ERGONOMICS, 2000, VOL. 43, NO. 10, 1651± 1660. 12. Raoul R.D. Oudejans ,Rolf W. van de Langenberg, R.I. (Vana) Hutter. Aiming at a far target under different viewing conditions: Visual control in basketball jump shooting. Human Movement Science 21 (2002) 457–480

Murdoch University...