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10:20   Upper extremity kinematics Chair: Daan Bregman 10:20 20 mins COMPARISON OF DIFFERENT TYPES OF SHOOTING ARM MOTIONS IN BASKETBALL Hiroki Okubo, Mont Hubbard Abstract: Introduction One hand set and jump shots are most commonly used in basketball games. Shooters hold the ball in the shooting hand, set it near their forehead, raise and extend the elbow and snap the wrist forward. Many players use shoulder, elbow and wrist rotations, but some use mostly their elbows and wrists. To avoid blocked shots, they position the ball high and snap their wrists in shooting. In general, different types of shooting arm motions are used for different skill sets and/or court situations. Tsarouchas et al. (1990) studied shooting styles and compared a high elbow technique to a lower elbow starting position. Okubo and Hubbard (2015) have derived the kinematics of the shooting arm motion and showed the arm joint angular displacement and velocity combinations. No dynamic model including a basketball has been used to investigate different types of shooting arm motions. In this paper, a simulation model analyzes three types of shooting arm motion for shots with low elbow, high elbow and high wrist starting positions. Method We use a two-dimensional three-segment model. The shooting arm is assumed to move in the vertical plane and to have three rigid links with rotational joints for the upper arm, forearm and hand links at the shoulder, elbow and wrist. The model analyzes possible release conditions for the three types of shooting motion assuming that the shoulder joint is fixed and that there is no slipping between the fingertip and the ball surface at the fingertip contact point. In shots with low elbow starting position, shooters rotate their upper arm, forearm and hand to produce the desired ball release conditions. In the shot with the high elbow starting position, they fix the elbow and rotate the forearm and hand. Wrist rotation contributes almost all the ball release velocity and backspin in the shot with the high wrist starting position. Results The model estimates possible arm joint angular displacement and velocity combinations for a given ball release condition. The three types of shots have different shooting arm configurations at release. Many possible shooting arm configurations exist for the shot with low elbow starting position. Shots with the high wrist starting position have a smaller set of shooting arm configurations and also require a larger magnitude of wrist torque. References Okubo, H. and Hubbard, M. (2015) Kinematics of arm joint motions in basketball shooting, Procedia Engineering, 112, 443-448. Tsarouchas, E. Kalamaras, K. Giavroglou, A. and Pressas, S. (1990) Biomechanical analysis of free shooting in basketball, In: Kreighbaum, E. and McNeill, A. (Ed.) Proceedings of the Sixth International Society of Biomechanics in Sports Symposium, International Society of Biomechanics in Sports, Bozeman, MT, 551-560. 10:40 20 mins CONTRIBUTIONS OF JOINT TORQUES, MOTION DEPENDENT TERM AND GRAVITY TO THE GENERATION OF BASEBALL BAT HEAD SPEED Sekiya Koike, Kohei Mimura Abstract: Baseball batting is one of the most difficult tasks in sports motion. A batter is required to accelerate bat head speed within 0.2-0.3 [s] and move the bat into the hitting point with proper timing. From the analysis based on multi-body dynamics, a high speed swing motion is caused by not only joint torque and gravity but also motion dependent term (MDT). The MDT consisting of centrifugal force, Coriolis force and Gyro moment is characteristics of multi-segment motion. The purpose of this study was to quantify the dynamic contributions of joint torques, motion dependent term, and gravity to the generation of baseball bat head speed. Five collegiate baseball players participated in this experiment as subjects. They performed hitting a teed ball as strong as possible. Three-dimensional coordinate data were captured by a motion capture system (VICON MX+, 12 cameras, 250 Hz). The whole-body segments and bat were modelled as a system of sixteen-rigid linked segments, and constraint axes of the elbow, wrist, knee and ankle joints were modelled with anatomical constraint equations in order to consider the degree of freedom (DOF) of the joint. The equation of motion with respect to the whole-body and bat was obtained by considering modelling errors, such as, residual joint force and moment, and fluctuation of segment’s length. Kinetic data of each hand and each foot were obtained by using an instrumented bat equipped with 28 strain gauges and 3 force platforms. The dynamic contributions of the joint moments, motion dependent term and gravity term to the bat head speed were derived from the equation of motion for the system. The results obtained by this study show that motion dependent term is the largest contributor to head speed at the impact. The contributions of gravity and modelling error terms show small values. Motion dependent term is the main generating factor to the generation of bat head speed at the impact in baseball batting motion. 11:00 20 mins ELITE ATHLETE MOTOR AND LOADING ACTIONS AT THE SHOULDER DURING BASEBALL PITCHING Xavier Gasparutto, Erik van der Graaff, Frans van der Helm, Drikjan Veeger Abstract: INTRODUCTION Deep understanding of the actions occurring at the shoulder during pitching could help preventing injury by training specifically the structures that are the most solicited and would also avoid counterproductive training. METHOD 8 pitchers from the Dutch AAA team (age: 16.1 ± 0.7years, size: 1.82 ± 0.8m, weight: 76.9 ± 8.1 kg) participated in this study. Pitchers were equipped with skin markers, including 6 and 4 markers on the throwing upper limb (UL) and thorax. They performed 5 fastball pitches from a pitching mound. 3 pitches per players were used. The motion of the markers was recorded by a 10-camera (T40S, 100Hz) VICON system. The proposal from the ISB (Wu et al. 2005) was used for the definition of the local coordinate systems (LCS) and joint coordinate systems (JCS). Regression equations (Dumas et al. 2007) were used to estimate the gleno-humeral joint position and mass and inertia of the UL. Inverse dynamics was performed to compute the net actions at the shoulder. The motor actions were computed as the projection of the net actions in the direction of movement. The loading actions, were computed as the difference between net and motor actions. Finally the actions were projected on the JCS of the shoulder (e1: ythorax , e3: yhumerus, ). RESULTS The maximal motor force (166N) is in the forward direction at maximal external rotation (MER). The maximal loading force (600N) occur at ball release (BR) in the pulling direction. The maximal motor moments are in exo-rotation (28 Nm) at MER and endo-rotation (-20Nm), 20ms after BR. The maximal loading moments occurs at MER (-48Nm elevation, 85Nm forward) followed at BR by a maximal backward moment (-55Nm) and a maximal depression moment at MER (68Nm). CONCLUSION Most of the net actions are loading that maintain stability and coaptation of the joint. This suggest that the pitching power is mainly transmitted and not produced by the shoulder. The main motor actions before BR are forward force and exorotation moment suggesting that the endorotation before BR is mainly passive and produced by the motion of other segments. REFERENCE Wu et al., ISB recommendation on definition of JCS of various joints for the reporting of human joint motion-PartII : shoulder, elbow, wrist and hand, 2005, JB 38,p981-92 Dumas et al., Adjustments to McConville et al. and Young et al. body segment inertial parameters, 2007, JB 40,p 543-53