the situation at throwing
In the last ten years, the hammer throwing had seen a fast increase. The meaning of each rotation of the topthrowers was differently interprated and from this, the final peak acceleration of the hammer before the throw was executed with individuell solutions. My job as coach is - in the technical domain - to recognize the structure of the movement- and forcesystem of the hammer throw and to promote the fundamental qualities of the athletes with regard to the individuell peculiarities. I try to show - for example the throw of Juri Sedych1 - with which means of movement (rotation,translation,lift) he tries influence the forces- and moments of inertia.
2. methods
guided by the world record2 - throw of Sedych, I discuss the above mentioned influences and their effects.
1 J. Sedych USSR, born on 11.6.55, height 1.85m, weight 110 kg, a.o.t. two times olympic-winner
2 In the pictures: the winning-throw about 86.74m at the EM 1986 in Stuttgart/BRD
the interesting pictures 1-6 magnified
1. just before the termination of the third one-legrotationphase
2. tread by the right foot and the beginning of the two-leg-supportphase
3. set up the rotationaxis and the beginning of the maximum final acceleration
4. shifting the rotationaxis to the left and starting the throw by optimal final acceleration by lift
5. the hammer has the highest acceleration absolutly strechted against the hammer, just before releasing the tension
6. letting go of the hammer
3. insights and discussion
The keeping of the hammer in orbit (produce the centripetalforce) and the increase of the angular velocity happens mainly by aimed and dynamic force-commitment (push the right side hip in a turning direction at a high level) of the right leg while keeping the body axis on the left. Trying simultaneously to raise the orbital velocity by the maximum of the rotation radius.
As we see in picture 2,3,4, the `system` between the athlete & the hammer is not symmetrical.
'Because of the wire take no direct tangentail effect for the equipment, so the tractive power has to form an angle with the momentary curvature radius.'1
In general, between orbital velocity and centrifugalforce the following physical laws are in valid:
| v=wr | orbital velocity of the hammer |
| r=v2/ar | curvature radius of the orbit |
| ar=(Fzp+FHP)/m | centripetal acceleration of the hammer |
| m | mass of the hammer |
| Fz | pullingforce at the wire of the hammer |
| Fzp | centripetalforce (the vice versa force is called the centrifugalforce) |
| Fzt | tangentialforce, equaling a higher velocity |
| Fzn | normalforce, it`s orthogonal to Fzp and Fzt |
| FH | weightforce of the hammer |
| FHp,FHt,FHn | compounds of FH, equaling direction like compounds of Fz |
| equaling: | ar=v2 / r and Fzp=(mv2/r) - Fhp |
1 comment, pictures and legend from Renzo Pozzo `Leistungssport 3/87`
Too fixed views - and that`s the question here, because the system `thrower-equipment` moves with ist complex structure in the space - are in my opinion not ideal for learning to understand the individuell aspired solution.
Let us follow the pictures 1 to 6 like a film and complete our view with the messurements, done in Stuttgart:
- the height of the hipcentre was in pic. 1 68 cm, in pic. 6: 94 cm; equaling a hight difference of 26 cm
- the accelerationway in pic. 2 to 6 was 6.64 m, Sedych needed 0.26 sec for it
- Sedych set up his right foot as the hammer was at 224.9o The throw took place at an azimuth of the hammer at 97.3o. As we see in pic. 3, the body-twisting was at a maximum of +43o and in minimum of -14o (pic. 6); equaling a difference of 59o. The throwing angle was 41.1o
As a result of the extremely, early setting of the right foot, Sedych is able to give the hammer an enourmous lon acceleration - by pushing the right leg; that`s for set up the systemaxis against the fulcrum (left heel) - by maintenance of the system-effect (possibly small deflexions between hip- and shoulderaxis, ergo big radius of systemaxis and equipment - and further to initiate an angular moment, which accelerates the equipment about 28.7 m/s, by an incredible lift. The throwing angular about 41.1o seems insufficient, but if you watch at the maximum lift or counter to the hammer in picture 6, that does not break off the final acceleration too early, so we can suppose, there is more impotance in lifting `over left/against left`, than in a higher throwing angular. Sedych tries to exert influence on the inertia of the hammer until the last moment (compared to the position of the left shoulder in pic. 6) and to optimize the centripetal- and the tangentialforce by his optimal bearing to the equipment.
4. conclusions for the practice
It`s necessary to accelerate the hammer as steadily as possible during the rotation. Sedych succeeds in it and so you can realize, that the system `thrower and equipment` can accelerate by the legs. That implies a stable turningaxis and provides that the moment of inertia does not enlarge in spite of the higher tangential velocity.
The optimal hammer(throw)velocity comes about, if
- the one-leg turningphase `on the left,over left but against the left` can happen temporaly as well as being spatially harmonious and relatively quick
- the setting after it happens actively on the right, and the rotationaxis can be set up soft but with a high pressure over left
- the throwing happens not too fast but if the hammer can lift up over the left heel to 90o and after it be released (by the shoulders)