MEASUREMENT OF AMORTISATION AND TAKE OFF FORCE IMPULSE DURING THE JUMP WITH BOTH LEGS
AbstractThe various of jumps belong to currently used training methods. They are used to test and determine the state of training level. It is also convenient for training process management. Squat jumps and coutermovement jumps allowed to find out the parameters of slow muscle work (stretch-shortening cycle) a drop jump can help as to find out the parameters of fast stretch-shortening cycle. There exists an optimal height of drop jump in which can be reached an optimal using of amortisation impulse. All types of jumps have force impulse compound from the amortisation impulse (Ia) and takeoff impulse (It). The squat t jump is an exception. Duration, sue and shape of impulse are suitable parameters for quantifying and management of training The dynamometric board KISTLER shows the course of total force impulse and the duration of flying phase t, of the jump The total force impulse applies m Is= Ia + It (1) The height of the jump can be calculated from the -off impulse in formula h = I;/(2mZg) (2) Applied formula for height of the jump calculated from the flying phase h = 1/8(gt,2) (3) After calculation of the formula (3) we are able to substitute the height of the Jump into the formula (2) and we gain relation for the takeoff Impulse It is I, = l/2(gtfm) (4) Using substitution for relation (4) to (1) we calculate the sue of the amortization impulse. The term height of the jump is understood as the difference between the highest point of trajectory of gravity centre and gravity centre m standing (both are measured at the vertical axis). The part of the jump is also a lifting of the body on the tiptoes just before finishing the takeoff phase of the jump. The lifting has the influence for the force impulse size I,. The first contact with the ground is through tiptoes. These facts have been taken into the consideration in calculating the height of the jump from flying phase by the formula (3) and in calculating the amortization impulse Ia
Coaching and Sports Activities
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