Kinematic Analysis of the Sidearm Throw in Ultimate Frisbee: Motion of the Wrist

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opasdfghjklzxcvbnmqwertyuiopasdfg Paul Taylor

Independent Project- Paul Taylor 0601273

1.0 Table of Contents 1.0 TABLE OF CONTENTS ................................................................................................................................ 2 1. ABSTRACT ........................................................................................................................................................ 3 2. INTRODUCTION ............................................................................................................................................. 4

2.1 BACKGROUND.................................................................................................................................................................. 4 2.1.1 Aims ............ ............. ............. ............. ............. ............. .............. ............. ............. ............. ............. ............. ............ 6 2.2 LITERATURE REVIEW .................................................................................................................................................... 6 2.2.1 Gyroscopic Effect ............. ............. ............. ............. ............. .............. ............. ............. ............. ............. ............ 6 2.2.2 Aerodynamic Lift Lift & Pressure ............ ............. ............. ............. ............. .............. ............. ............ .............. ... 7 2.2.3 Use of Reflective Markers Markers ............ ............. .............. ............. ............. ............. ............. ............. .............. ......... 8 2.6 OBJECTIVES .................................................................................................................................................................. 10 3. METHOD ..................... ..................... ...................... ...................... ..................... ...................... ...................... ..10

3.1 SUBJECTS ....................................................................................................................................................................... 10 3.2 EQUIPMENT, EXPERIMENTAL SET-UP & DESIGN ................................................................................................... 11 3.3 ANGLE CALCULATION & DEFINITIONS OF MEASURED VARIABLES ....................................................................... 12 3.3.1 Equations ........................................................................................................................................................... 12 3.4 SAFETY .......................................................................................................................................................................... 13


Kinematic Analysis of the Sidearm Throw in Ultimate Frisbee: Motion of the Wrist

1. Abstract The purpose of this study was to investigate the joint kinematics during the sidearm throwing motion. To date, little research has been conducted on the release parameters of the sidearm throw in Ultimate Frisbee. A kinematic three-dimensional high-speed analysis was conducted, measuring the joint angles of the forearm and wrist from the moment the pivoting foot came into contact with the ground until post release of the sports disc. A single male participant (Age; 20) case study was selected; with with a minimum of three years of high level competitive Ultimate experience including participation in 3 National Student competitions. The subject was instructed to throw 35 slow (normal) and 35 fast (maximal effort) sidearm throws. Using two gen-locked Basler high-speed cameras at 200 Hz, released parameters were measured using reflective markers positioned at three points along the


2. Introduction 2.1 Background Originally introduced during the Ancient Greek Olympics, the popularity of using a flying disc within sport has significantly increased during the last half century (Rhode, 2000). 2000). The technologies introduced during the Second World War led to the development of novel manufacturing procedures procedures such as moulding. As a result, a prototype of the modern sports disc was created, with the Wham-O Corporation, California, trade marking the new invention as a ‘Frisbee’ based on the original ‘Frisbie Pie Tin’ (Rhode, 2000).

At the present time, there are more Frisbees sold each year than the combined number of retailed baseballs, basketballs and footballs (Wham-O.com). (Wham-O.com). The increasing increasing demand for Frisbees has seen the introduction of many new exciting and competitive sports such as


velocity and release angle have to optimised, release height is not a significant variable within Ultimate. Release height in nearly all throwing sports is very influential to the throw outcome. In contrast, invasion sports such as American football and Ultimate are not influenced by genetic differences such as height and mass of a performer when determining throwing motions. The correct technique during build up and release of the sports disc remains the same for all competitors although individuals may adapt the general technique.

Strudarus (2003) identified a variety of adapted throws used by players during a competitive match including, the backhand throw, sidearm throw, hammer throw, scoober and blade. Sasakawa & Sakurai (2008) additionally identified that backhand and forehand (fig 1.) as the most frequently used throwing motions. The Throwing action required in Ultimate has been recognised as the most important skill, with players requiring sufficient ability to throw a variety of passes quickly and more importantly with accuracy. accuracy. Due to the limited limited offensive playing space available during during a


2.1.1 Aims The purpose of this study was to develop a further understanding of the forearm joint kinetics building upon the three-dimensional analysis completed by Sasakawa & Sakurai (2008). The variables to be identified throughout the forehand throwing motion were; maximum and minimum values for the angle of pronation, pronation angular velocities, spin rate, disc linear velocities, wrist angles & wrist angular velocities. In addition, the identification of release parameters and attributes that occur between slow and fast release throws would provide future coaches and both novice and elite players with an innovative knowledge about forehand release mechanics. 2.2 Literature Review Upper limb and hand movements have been reviewed, in general, as complex (Murgia, 2005). The wrist has been defined as containing two degrees degrees of freedom (DOF): radial/ ulna deviation and flexion/ extension (Metcalf, Notley, Chappell, Burridge &Yule, 2008). Literature has previously tried to identify the movement of the wrist; Miyata, Kouchi,


same. All the throws discussed in this study study are of a right-handed forehand, resulting in an anti-clockwise disc rotation during flight, when observed from an elevated position. Assuming rotation is occurring, a lift force L is experienced perpendicular to the flat upper surface and velocity v / drag forces D.


when assuming lift will be reduced on the opposing edge, causing an incline or roll during flight, data repeatedly collected by Potts & Crowther (2002) significantly rejects this theory.

Due to the symmetrical design of the disc the COM will always be in the centre, however as displayed in Fig 2. the COP can become off-centre typically as a result of the natural incline of the front edge of the disc during flight (Hummel, 2003; Morrison, 2005). Torque is created due to the slight lift which is experienced at the exposed edge of the disc; when rotation does not occur, torque can cause the disc to flip upwards, effectively stopping any controlled flight to continue (Morrison, 2005). 2.2.3 Use of Reflective Markers Hummel & Hubbard (2001) conducted a study determining an appropriate musculoskeletal model of the backhand throw. Conducting kinematic kinematic analysis using 180 Hz high speed cameras, four subjects subjects provided segment segment orientation data using using reflective markers. Using known orthogonal coordinates of individual body segments measures for joint torque,


the study’s aim to provide coaching specific feedback for novice athletes, due to the lack of

realistic data.

A study conducted by Gordon & Dapena (2006) aimed to measure the contributions of body segment motion in comparison to tennis racket head speed. The study conducted a 3D analysis and specifically focussed on the use of surface markers and joint centres to calculate accurate arm twist orientations. The researchers concluded from the research that the skinattached markers could not correctly identify and calculate upper arm twist orientation due to unforeseen skin movement. In addition, joint centre calculations produced levels of error exceeding 20%. Cappozzo, Catani, Leardini, Benedetti Benedetti & Della Croce (1996); (1996); Reinschmidt, van den Bogert, Nigg, Lundberg & Murphy (1997) acknowledged that motion of skinmounted markers do not follow accurately the motion of the underlying bones. This inconsistency of accurate reflection of segment motion therefore compromises the potential accuracy of computed outputs through digitisation.


Figure 3. Model of the arm with a carrying angle at the elbow (as cited in Gordon & Dapena, 2006).


form; he was selected due to the high level of previous competitive performance; this specifically included participation in 3 National Student competitions, as a member of the varsity ultimate Frisbee team based at the University of Chichester (England) and a minimum of three years playing experience. 3.2 Equipment, Experimental Set-up & Design Testing was completed in an indoor facility, at the University of Chichester, to eliminate the effects of wind. All throwing trials were recorded recorded using two gen-locked gen-locked synchronised highspeed cameras (Basler, A602fc-2, Germany) at 200 Hz. The cameras were positioned in front of the subject, with a separation distance of 3.9m at angle of approximately 60°, and placed on tripods at a height of 2m.


Figures 7, 8, 9; reflective markers and extension arm placement on forearm and disc. The rods attached along the forearm were aligned orthogonal to each other, with the noncavity surface of the disc marked with three reflective markers at 120° to each other. A pretest was conducted to visually assess the disc performance prior and post attachment of the reflective markers. It was reviewed from footage that flight was not compromised by the additional weight of the markers. 3.3 Angle calculation & definitions of measured variables


Pronation angular velocity and hand angular velocity were obtained o btained using digitisation linear transformation (DLT) of the 3D coordinates of anatomical landmarks (Figure 10).

B

x

B

θ

C A C

A

Figure 11. displays the linear transformation of the disc and calculation of spin rate. Disc linear velocity was calculated from knowledge of the distance moved with respect to


A direct linear transformation (DLT) methodology was used, as developed by Abdel-Aziz & Karara (1971). Three-dimensional coordinates of landmarks obtained from all video footage were computed. Digitising of all reflective markers (including disc) were completed for both camera angles. Due to image clarity, an optimum 15 trials were digitised for both the normal and maximal effort throws (Total Number = 30 trials). All 30 trials were initially cropped using an anchor event: ground contact of the unplanted foot, during the pivoting motion, from an initial standing position.


4.0 Results 4.1 Result for Release Parameters To explore the discrepancies between the fast and slow trials for all of the measured variables during the sidearm release in Ultimate Frisbee, paired samples t-tests were conducted. Mean values (± standard deviations) for all measured release parameters are provided in table 1. A significant difference difference (p< 0.05) between the fast and slow trials was recorded for disc linear velocity which indicates a valid distinction for testing. For the seven parameters investigated, significant differences were recorded within maximum pronation angles, pronation angular velocity and wrist angle. No significant difference was recorded for minimum pronation angle and wrist angular velocity however; mean values for spin rate suggest a possible difference although no significance was observed. Table 1. Results for release parameters


steady increase in supination peaking approximately 0.09s (slow) and 0.015s (fast) before release. This therefore indicates that there is an apparent cocking and unwinding phase figure 20. (phase’s 1 -3). It can be observed that supination is occurring throughout the whole motion but the transition from maximum, prior to release and the immediate increase in forearm pronation during release can be identified as a major contributor to disc projection. In contrast to increased measures of pronation angle for the fast trials, statistics reported a significant difference for pronation angular velocity (forearm swing motion); the slow trials produced elevated levels of angular velocity in comparison to fast. Figure 14. displays the transformation for pronation angular velocity, the most substantial difference between the trials in addition to the increase in mean velocity (slow) is the length of time taken during the unwinding phase. Figure 14. visibly demonstrates that although the slow trials reported an overall increase in mean angular velocity, the unwinding phase for slow trials approximately lasts only 0.03s in contrast to 0.12s for fast trials. tr ials.


Figure 14. displays fast (red) and slow (blue) transformation in pronation angular velocity ¹). (°s  ¹).


Figure 17. displays fast (red) and slow (blue) transformations in wrist angle (°).


4000 3500 3000 2500 2000 1500 1000 500 0 1

2

Figure 19. shows the mean (± standard deviations) of spin rate for the slow (1) & fast (2) trials. Due to large standard deviation within both the fast and slow trials a significant difference


5.2 Throwing motion and disc release parameters Sasakawa & Sakurai (2008) identified an important trend for the angle of attack between skilled and unskilled performers. They reported that for the skilled performers the angle of attack was almost 0°, resulting in the disc being accelerated more smoothly during and postrelease due to minimal levels of air resistance. It was additionally identified that this allowed skilled performers to increase throwing distance despite similar initial velocities. The present study also supports the notion of disc release occurring parallel to the plane of movement (Figure 20). Linear velocities were noted to vary from the study conducted by Sasakawa & Sakurai (2008) who recorded initial linear velocities of 21.7 ± 1.7 (skilled); 20.7 ± 2.5 (unskilled) in contrast to 12.701 ± 1.221 for fast trials within the current study. The apparent large variation in linear velocities cannot be identified, it is however to note that the participants in study by Sasakawa & Sakurai (2008) were required to throw the disc as far as possible.


force production must have an additional source, other than pronation angle & angular velocity.

Sasakawa & Sakurai (2008) reported small ranges of pronation angles for skilled throwers and in addition, identified that disc spin rate was unlikely to have been produced directly from a pronation motion of the forearm. However, indirectly it was reported that pronation just prior to release enabled a more effective range of plantar flexion motion. This inc reased plantar flexion was believed to provide greater spin rate to the disc. The current study further identified an increase in pronation just prior to release and in fast trials identified a significant increase in plantar flexion (hand angle), supporting the findings of Sasakawa & Sakurai (2008). It was however found that no significant difference was reported for spin rate between fast and slow trials. As previously identified, it is important to recognise the results (Figure 19) clearly display spin rate having an increased mean for fast trials, however an increase in trials may have provided clarity. No significant difference was observed for


From the results of this study there is a clear indication that development of forward momentum needed to project the disc linearly, at any given velocity, must be initiated in addition to the motion of the forearm and wrist. This is due to no significant difference being identified between the hand angular velocity and pronation angular velocity variables. Sakurai, Ikegami, Okamoto, Yabe & Toyoshima (1993) identified the following motion during the acceleration phase of baseball pitching: rapid shoulder internal rotation, elbow extension, ulnar flexion and pronation. This series of sequential motions strongly reflects those acknowledged in the both the current study and in the findings of Sasakawa & Sakurai (2008). Therefore, it can be proposed that the Ultimate Frisbee forehand throw strongly resembles the overhand throw in baseball pitching. Additionally, Feltner & Dapena (1986) documented the shoulder and elbow motions, 0.2s prior to release in baseball pitching using a 3D analysis. They reported that internal rotation of the shoulder and extensions of the elbow were important attributes to the success of pitching motions. A more recent study by Dillman, Fleisig & Andrews (1993) also identified internal rotation of the shoulder, extension of the elbow, pronation of the forearm & ulnar deviation of the wrist just prior to release


However, it was additionally suggested that this may have been as a resultant of the size and shape of the projectile and grip required to throw.

5.3 Future considerations In the current study a single subject protocol was used to test the methodology of 3-D kinematics, although may not be universally applicable, relevant differences between variables should be highlighted. A future direction may be to use a cohort of athletes, including a variation in technical ability to help identify trends between release parameters that maybe apparent. This in turn could assist coaches in identifying correct techniques or additionally, comprising efficient exercises in practice to progress athletes on both a team and individual level. Furthermore, it is important to identify the differences between coaching manuals and previous literature when regarding release parameters. It is apparent that little or no kinematic analysis has been achieved in an outdoor environment and given the influences of external factors such as wind, as this may have a major impact on release


Furthermore, just prior to release the forearm and wrist motions displayed pronation from an initial supinated position, palmar flexion, extension at the elbow and plantar flexion. Spin rate was found not to display a significant difference between fast and slow disc release rates; however errors during the digitising process may have masked subtle differences. The three-dimensional approach chosen for this study can provide coaches and athletes with the capability to gain a clearer understanding of the kinematics of the sidearm throwing motion. It is however, important to acknowledge individual differences in technique could vary and the study was only conducted with a limited resource.


7.0 References

Aguinaldo, A.L., Buttermore, J. & Chambers, H. (2007). Effects of upper trunk rotation on shoulder joint torque among baseball pitchers of various levels. Journal of Applied Biomechanics, 23, 23, 42-51.

Bahamonde, R.E. (2000). Changes in angular momentum during the tennis serve. Journal of Sports Science, 18, 18, 579-92.

Bahamonde, R.E. (2005). Review of the biomechanical function of the elbow joint during tennis strokes. International Journal of Sports Medicine, 6, 42-63. Cappozzo, A., Catani, F., Leardini, A., Benedetti, M.G. & Della Croce, U. (1996). Position and orientation in space of bones during movement: Experimental artefacts. Clinical Biomechanics, 11, 11, 90-100.

Danna, M. & Poytner, D. (1979). Frisbee handbook . Quick Fox Company: Santa Barbara.


application of a computational model for wrist and hand movements using surface markers. IEEE Transactions on Biomedical Engineering, 55, 55, 1199-1210. Miyata, N., Kouchi, M., Kurihara, T. & Mochimaru, M. (2004). Modelling of human hand link structure from optical motion capture data. In Proc. Int. Conf. Intelligent Robots Systems, pp. 2129-2135. Sendai, Japan.

Morrison, V.R. (2005). The physics of o f Frisbees. Journal of Classical Mechanics and Relativity ,8, 1-12.

Murgia, A. (2005). A gait analysis approach to the study of upper limb kinematics using activities of daily living. Ph.D. dissertation: University of Reading, UK.

Palastanga, N., Field, D. & Soames, R. (1998). Anatomy and human human movement . Oxford: Butterworth Heinemann. Panton, R.L. (1995). Incompressible flow. John Wiley and Sons: London, UK. Potts, J.R. & Crowther, W.J. (2002). Disc-wing UAV: A feasibility study in aerodynamic control. CEAS Aerospace Aerodynamics Research Conference: Cambridge, UK. Putnam, C.A. (1991). A segment interaction analysis of proximal-to-distal sequential segment


8.0 Appendices


Appendix 3 Raw Data Outputs

Appendix 1 Raw data

Appendix 2 t-test Results

Appendix 2 Paired samples t-test Results Paired Samples Statistics Mean Pair 1

Pair 2

Pair 3

Pair 4

Pair 5

Pair 6

N

Std. Deviation

Std. Error Mean

S_min_pro_ang_3Dangles

2.78838

13

5.680610

1.575518

F_min_pro_ang_3Dangles

.46638

13

.711979

.197467

S_max_pro_ang_3Dangles

52.46769

13

21.672939

6.010992

F_max_pro_ang_3Dangles

30.45985

13

14.855554

4.120189

S_Pro_ang_3D_angular_vel

459.67860

10

206.166476

65.195564

F_Pro_ang_3D_angular_vel

250.70620

10

150.131704

47.475813

S_3Dlinear_vel_Rel_Vel

10.32338

13

.767563

.212884

F_3Dlinear_vel_Rel_Vel

12.70069

13

1.220553

.338520

S_3D_angluar_vel_Spin_angle

1688.18588

8

622.722780

220.165750

F_3D_angular_vel_Spin_angle

2392.98012

8

1253.748548

443.267050

16.18083

12

2.846911

.821832

S_htw_3D_angles

Appendix 2 Paired samples

t-test

Results

95% Confidence Interval of Std. Error Mean P S_min_pro_ang_3Dangles ai F_min_pro_ang_3Dangles

Std. Deviation

Mean

the Difference Lower

Upper

Sig. (2t

df

tailed)

2.322000

5.876614

1.629879

-1.229202

5.873202

1.425

12

.180

22.007846

19.585509

5.432043

10.172442

33.843251

4.051

12

.002

208.972400

245.615687

77.670500

33.269522

384.675278

2.690

9

.025

-2.377308

1.378322

.382278

-3.210220

-1.544396

-6.219

12

.000

-704.794250

1481.707576

523.862737 1943.532783

533.944283

-1.345

7

.220

-4.845000

5.362584

-8.252223

-1.437777

-3.130

11

.010

7.770556

368.959485

122.986495 -275.836811

291.377922

.063

8

.951

P S_max_pro_ang_3Dangles a F_max_pro_ang_3Dangles P S_Pro_ang_3D_angular_vel air F_Pro_ang_3D_angular_vel P S_3Dlinear_vel_Rel_Vel air F_3Dlinear_vel_Rel_Vel P S_3D_angluar_vel_Spin_a S_3D_angluar_vel_Spin_angle ngle air F_3D_angular_vel_Spin_angle P S_htw_3D_angles - F_htw_3D_angles air P S_htw_3D_angular_vel air F_htw_3D_angular_vel

1.548045

Appendix 3 Trace 1: Pronation 3D angles

Appendix 3 Trace 1: pronation 3D angles (°) (fast = red; slow = blue)

Appendix 4 Trace 2: Pronation 3D angular velocities

Appendix 4       ¹) ¹) (fast = red; slow = blue)

Appendix 5 Trace 3: Disc linear velocities

Appendix 5 Trace 3: Disc linear ve  ¹) ¹) (fast = red; slow = blue)

Appendix 6 Trace 4: Spin Rate

Appendix 6     ¹) ¹) (fast = red; slow = blue)

Appendix 7 Trace 5: Hand-to-wrist 3D angle

Appendix 7 Trace 5: Hand-to-wrist 3D angles (°) (fast = red; slow = blue)

Appendix 8 Trace 6: Hand-to-wrist 3D angular velocities

Appendix 8   --     ¹) ¹) (fast = red; slow = blue)

Kinematic Analysis of the Sidearm Throw in Ultimate Frisbee: Motion of the Wrist

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