A THREE-DIMENSIONAL ANALYSIS OF THE ANGULAR VELOCITIES OF SEGMENTS IN JAVELIN THROWING
Keywords: javelin throwing, kinematics 3D-kinematography, angular velocities
AbstractINTRODUCTION: The pattern of movement of the throwing phase (last double foot contact) based on energy transmission between segments has been demonstrated by numerous researchers through the observation and processing of the sequence of linear velocities or kinetic energy of the segments. However, there is a lack of information about the angular velocities. The objective of this work is to analyze the movements of rotation of the segments about their three anatomical axes and search for a pattern of movement based on the sequence of angular velocities from proximal to distal segments. METHODS: The experimental technique used was 3D-photogrammetry (DLT algorithm). A total of 36 throws by two national-level throwers were analyzed. Two cine cameras were used at 200 Hz. The data were smoothed by quintic spline functions. The angular velocities of the segments were calculated through the first derivative of the unit vectors of local frames fixed with the segments. The data used in this case were: the angular velocities of the thorax, upper arm and forearm about the anatomical axis of the thorax; also, the angular velocities of the pelvis were calculated about its own three axes. Time was normalized (0%: left foot contact, 100%: release). RESULTS: The average peaks of angular velocity about the anterior-posterior axis (x) proved the existence of important movements of the thorax (-3.4 rad/s), upper arm (-11.89 rad/s) and forearm (+14.9 rad/s) in the frontal plane – data for subject A. Also, average maximums of angular velocity about the transversal axis (y) demonstrated large movements of flexion in both subjects. [table] Large values of angular velocity about the longitudinal axis of the trunk were found (see table). Inverse correlation coefficients between the increments of angular velocity were found for wy and wz in the temporal intervals defined by the peaks of angular velocity. For example, for subject A, at the pelvis-upper arm interval the correlation between the decrease of z angular velocity of the pelvis and the increase of the upper arm was -0.76 . CONCLUSIONS: A pattern based on the rotational movement of the segments has been demonstrated.
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