A BIOMECHANICAL ANALYSIS OF THE SUPPORT PHASES DURING THE PREPARATION AND TAKE-OFF IN LONG AND HIGH JUMPING
AbstractThe literature agrees that the goal for the take-off technique in long and high jumping requires a special preparation phase during the approach so that a lowering of the centre of gravity (C.G.) be achieved without a significant loss of running speed. The purpose of this study was to describe and compare kinematically the support phase during the penultimate stride and the take-off in the long and high jump. The long jump performance of the athlete K.K. (8.14m) and the high jump performance of the athlete L.P. (2.36m) during competition were recorded by two synchronized video cameras (30Hz). The 3-D analysis was performed by a video motion analysis system (Ariel Performance Analysis System). The sequence analysis included the last two strides (penultimate and takeoff) for both performances. The results confirm that both athletes perform the preparation phase for the take-off by lowering the vertical height of their C.G. during the penultimate stride 0.03m for the long jumper and 0.04m for the high jumper respectively. In general we found that the technique pattern of the kinematic chain of the lower extremities is similarly executed for both athletes during the penultimate support phase. The relatively high values of the large flexion of the knee joint (120") and the relatively low values of the vertical change of C.G. can by explained by observing the geometrical position of the different links (foot, shank, thigh) of the kinematic chain. The shank and thigh are moving from a vertical position to a horizontal one (knee flexion) while the link of the foot is moving from a horizontal to a vertical position simultaneously. This counterbalancing movement determines the low values of the change in the C.G.'s height. Referring to the technique pattern of the take-off, the movement analysis of the kinematic chain of the lower extremities shows that, generally, in both long and high jump performances the take-off pattern is similar. Moreover, it is important to note that, for the support phase of the takeoff a vertical acceleration of C. G. was found to occur during the amortisation as well as during the extension of the take-off leg.
Coaching and Sports Activities
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