Presentation on theme: "Angular velocity of dominant side leg during sweep phase, max_dom_leg_sweep (r/s) Foot spacing during the middle part of sweep phase, d feet_90 o (m)"— Presentation transcript:
Angular velocity of dominant side leg during sweep phase, max_dom_leg_sweep (r/s) Foot spacing during the middle part of sweep phase, d feet_90 o (m) Non-dominant side knee angle when non-dominant side foot leaves the back of the ring, non-dom_knee_takeoff (deg) Dominant side knee angle when dominant side foot touches ring during the transition phase, dom_knee_td (deg) Hip orientation Shoulder orientation Relative separation angle between torso and pelvis, torso/pelvis_max (deg) Relative dominant side arm angle at beginning of thrusting phase, humerus-torso_tp (deg) Shot x-z plane release angle, release_xz (deg) Shot release position, h release (m) Shot release velocity, V release_xz (m/s) Distance between feet during thrusting phase, d feet_tp (m) First step distance of dominant side foot, d dom_first_step (m) First step distance of non-dominant side foot, d non-dom_first_step (m) Distance between non-dominant side toe and toe board during thrusting phase, d non-dom_foot/toe_board (m) Non-dominate side hip maximum velocity in throwing direction, V max_non-dom_hip_x (m/s) Non-dominant side foot angle during thrusting phase, non-dom_foot_tp (deg) Biomechanics Study of Collegiate Shot Putters Three male collegiate shot putters participated in the study using the rotational technique. The shot putters were classified as excellent, very good, and average performers in NCAA Division I. An eight camera Hawk Motion Tracking System (Motion Analysis Corporation, Santa Rosa, California) was used to record the motion. The three-dimensional coordinates for each reflective marker were captured at a sampling rate of 100 Hz. The system’s software (EVaRT) was used to identify the body surface locations associated with each marker and graphically display these marker coordinate trajectories in real-time, as shown in Figure 1. The marker displacements, velocities and accelerations were output to a spreadsheet and analyzed using LabVIEW and Matlab software packages. A right hand coordinate system was used with x as the throwing direction and the x-y axes representing the plane of the throwing circle. The study was conducted in an indoor training facility (Figure 2) equipped with an indoor shot put ring. The collegiate 16 pound indoor shot put was used. Each subject wore tight- fitting clothing. Lightweight reflective markers were attached to 24 landmarks, Helen Hayes marker set excluding the head markers, on each subject. (Figure 3). The shot put was covered with reflective tape and used as another marker. MATERIALS AND METHODS RESULTS PARAMETER DEFINITIONS Figure 1. Real-time graphical display of motion tracking data acquired during rotational shot put. Figure 3. Thrower with markers attached. Figure 2. Test facility. W.P. Hnat, P.M. Quesada, D. Cowper, and N. White University of Louisville, Mechanical Engineering Session 1 (n=4)Session 2 (n=4) ParameterMeanStDevMeanStDev d full_throw (m)17.770.3316.380.37 d stand_throw (m)14.250.0514.110.17 V release_xz (m/s)12.450.1711.850.15 release_xz (deg) 36.333.2740.032.71 h release (m)2.140.022.130.03 V max_dom_dulna (m/s)10.280.269.860.17 L shot_put_path (m)3.380.063.350.04 d dom_first_step (m)1.310.051.360.03 d feet_90 o (m)0.630.040.770.05 non-dom_knee_takeoff (deg) 145.704.85147.195.23 torso/pelvis_max (deg) 41.984.7634.802.28 humerus-torso_tp (deg) 96.912.0889.831.33 max_dom_leg_sweep (r/s) 15.570.8816.230.70 dom_knee_td (deg) 137.651.36140.041.86 non-dom_foot_tp (deg) 45.007.6931.1720.41 d non-dom_first_step (m)1.760.021.780.03 d non-dom_foot/toe_board (m)0.200.030.160.02 d feet_tp (m)0.510.020.490.03 V max_non-dom_hip_x (m/s)4.380.114.000.10 Table I. Parameter comparison between sessions for Thrower #1. Abbreviations: take-off (to), touch-down (td), thrusting position (tp), dominant-side (dom). Session 1 (n=4)Session 2 (n=4) ParameterMeanStDevMeanStDev d full_throw (m)15.630.3015.910.17 d stand_throw (m)14.250.0514.110.17 V release_xz (m/s)11.520.1511.740.10 release_xz (deg) 40.272.1735.131.68 h release (m)2.160.042.130.03 V max_dom_dulna (m/s)9.780.029.760.16 L shot_put_path (m)3.660.093.730.13 d dom_first_step (m)18.104.22.168.01 d feet_90 o (m)0.690.060.680.01 non-dom_knee_takeoff (deg) 145.252.04151.553.65 torso/pelvis_max (deg) 55.911.5947.641.60 d feet_tp (m)0.790.050.830.08 humerus-torso_tp (deg) 75.846.1880.661.92 max_dom_leg_sweep (r/s) 13.880.5316.080.03 dom_knee_td (deg) 143.091.0579.7941.00 non-dom_foot_tp (deg) 12.1210.0813.564.57 d non-dom_first_step (m)1.920.031.920.04 d non-dom_foot/toe_board (m)0.210.020.160.03 V max_non-dom_hip_x (m/s)3.700.063.510.07 Table II. Parameter comparison between sessions for Thrower #2. Session 1 (n=4)Session 2 (n=4) ParameterMeanStDevMeanStDev d full_throw (m)14.010.3614.670.36 d stand_throw (m)14.250.0514.110.17 V release_xz (m/s)10.730.2111.080.20 release_xz (deg) 39.833.0236.933.43 h release (m)2.250.052.200.06 V max_dom_dulna (m/s)9.320.119.380.22 L shot_put_path (m)3.520.073.480.05 d dom_first_step (m)1.240.091.270.01 d feet_90 o (m)0.670.020.750.02 non-dom_knee_takeoff (deg) 147.164.59153.712.96 torso/pelvis_max (deg) 57.130.7655.012.75 d feet_tp (m)0.480.050.590.02 humerus-torso_tp (deg) 94.743.6995.121.89 max_dom_leg_sweep (r/s) 16.760.1318.160.44 dom_knee_td (deg) 144.111.34N/A non-dom_foot_tp (deg) 67.905.1668.218.25 d non-dom_first_step (m)1.790.071.890.02 d non-dom_foot/toe_board (m)0.260.070.150.01 V max_non-dom_hip_x (m/s)22.214.171.1240.08 Table III. Parameter comparison between sessions for Thrower #3. DISCUSSION The most consistent finding, among the defined parameters for all throwers, was that shot release velocity was 1.5 to 2.5 m/s greater than dominant side distal ulna maximum velocity (i.e., velocity just prior to release). This velocity difference indicates that the wrist and fingers, during release, are capable of adding significantly to the shot velocity. The results indicate that the kinematics of the rotational throwing technique is unique to each thrower. However, important technical information is gained from analyzing the kinematic parameters for an individual thrower within and between sessions. Many new kinematic parameters of the rotational throwing technique have been defined and results from three collegiate throwers presented. A program was developed to read the marker data and compute all defined parameters.