A Uthor Abstra Ct

A biomechanical analysis of the © by IAAF individual techniques of the ham- 17:2; 15–26, 2002 mer throw finalists in the Seville Athletics World Championship 1999. by M. Gutiérrez, V.M. Soto, F.J. Rojas The work presented consists of a biomechanical analysis of the individual techniques of the hammer throw finalists at the World Championships held in Seville, Spain in August 1999. Three- dimensional photogrammetric Victor Manuel Soto works at the techniques were used to enable Department of Physical Education the most significant variables determining the throw’s efficacy at the University of Grenada in to be analysed and, consequently, Spain. to establish the inter-relationships between them, so making it possible to deduce the thrower’s individual technique. The initial temporal study analyses two con- AUTHOR secutive phases, the penultimate turn and the last turn, as well as the double and single support hammer system moves lineally across the stages. Reference is then made to throwing circle. All this is complicated fur- certain variables relating to the ther by the change in spatial orientation of positions and movements of the the plane that defines the pathway of the thrower-hammer system that are hammer in each turn (Dapena, 1984, 1986). significant for the distance ABSTRACT This fact, together with the relatively long reached (azimuthal angles). Final- time required to achieve the final hammer ly, the values are given for the speed, makes it difficult to analyse the fac- most relevant variables affecting tors that influence the distance of the each turn plus the temporal fac- throw, so much so that various solutions are tors, such as the radius of the possible. turn, speed and the angular Taking into account the contributory fac- momentum of the hammer head. tors which determine the distance of the throw, the tangential velocity of the hammer Introduction head at the moment of release (VtF) will be he hammer throw is characterised by determined by the increase in speed of each T the complex spatial structure of the turn, a rate of increase that is individual for action, where to achieve the maximum each thrower (Bondarchuk, 1987). It should final velocity of the hammer it is necessary reach its maximum value at the instant that to make two or three preparatory swings of the thrower releases it, when the projection the hammer followed by three, four or five angle (0) will be determined by the inclina- New Studies in Athletics • no. 2/2002 turns, while simultaneously the thrower- tion plane of the hammer in each turn, the 15 A biomechanical analysis of the individual techniques of the hammer throw finalists in the Seville 1999. thrower’s final action (Dapena, 1984, 1986) the resultant angular momentum (HR) during and the height of release (h), which depends the throw itself must be equal to the result- on the thrower’s anthropometric dimensions ant momentum of force exercised by the and the position adopted at the end of the thrower operating against the system. In this throw. Bearing these factors in mind, an indi- sense, the greater the rate of change in the vidualised analysis will show the variability in angular momentum of the hammer about its hammer throw technique. axis of rotation, then the greater the momen- The positions adopted by the thrower in tum of force exercised by the thrower will be each turn can be divided into two clearly dif- and this also applies to the internal forces ferentiated phases: (a) double support, where that the thrower has to support. This increase both feet remain in contact with the ground, in the angular momentum of the hammer and (b) single support, where the thrower affects other factors such as the average tan- turns, keeping only one foot on the ground. gential velocity (vm) and the average radius of Historically, special attention has been paid the turn in each phase (rm), which gives the equation E-1 that determines the angular to these phases, based on the theory that the momentum of the hammer (Dapena, 1978; hammer can only be accelerated in the dou- Dapena and McDonald, 1989). ble support phase, as the thrower cannot actively influence hammer speed during the EQUATION E-1 single support phase. On the basis of this theory, coaches have HR = mm ( rm x vm ) sought to prolong the double support phase Where H is the resultant angular momen- and, more particularly so, after the technical R tum of the hammer about the rotation axis changes proposed by Bondarchuk (1979, of the system, m is the mass of the ham- 1987) which were largely responsible for the m mer, rm is the radius of the turn and vm is excellent results obtained by Soviet throwers tangential velocity. over the past two decades. Moreover, the theory was apparently proved by the marked fluctuations in hammer speed in each turn, Knowledge of the values of the change in accelerating only in the double support angular momentum of the hammer during phase and reducing perceptibly in the single the throw, as well as its tangential velocity about the rotation axis of the system and its support phase (Kuznetsov, 1985; Dapena, radius of turn provides extremely relevant 1984, 1989 and Bondarchuk, 1987). data when analysing throwing technique, This theory has been questioned by Dape- especially when related to temporal data na (1984, 1986, 1989), who showed that it describing the action of the hammer during was possible to increase implement velocity the phases of double and single support in during the single support phase. Our own each turn. Thus, different authors conclusions lead us to assert that, at the very (Kuznetsov, 1965; Rolf-Gunter, 1979; Dape- least, the thrower cannot influence hammer na, 1984 and Bondarchuk, 1987) have put speed negatively, even when the thrower special importance on the variation of ham- pulls the hammer towards the body, until it mer speed during these two phases, proving reaches the highest point of its trajectory, that in each turn velocity increases in the leading to a situation where the thrower double support phase and tends to decrease moves rapidly in advance of the hammer. in the single support phase. However, if the thrower gets too far in Another factor of efficacy discussed in the advance of the hammer head, an excessive literature is the hammer’s plane of inclination torque of the line of the shoulders in relation to the horizontal, especially in the context of to that of the hips can be produced, causing its effect on the angle of release (Dapena, a reduction in the radius of the turn. 1984). The progressive inclination of the In dealing with the circular movement of plane of motion causes the hammer to rotate the thrower-hammer system, the change in about the horizontal axis, coinciding with the 16 New Studies in Athletics • no. 2/2002 A biomechanical analysis of the individual techniques of the hammer throw finalists in the Seville 1999. bisection of the angle of the throwing area and the first seven (with the exception of and of the throw itself. Therefore, for a right- the fifth placed) finalists in the Women’s handed thrower, there is a counter-clockwise hammer event at the 1999 World Champi- rotation about the vertical axis and a second onships held in Seville. The four turns and rotation of the hammer about the horizontal the final phase of the throw were analysed axis, visible as counter-clockwise from the in each case, except for Piskunov. He made frontal plane. The magnitude of this second five turns, and only the last four were rotation about the horizontal axis is related filmed. Table 1 sets out the names, nation- to the plane of inclination of the hammer ality, position, best throw in the Champi- and is a consequence of the application of onship (Sev99-Result), year the distance momentum of force along this axis. achieved in the throw under analysis Turning next to the positions adopted by (Sev99-Analysis) and the best mark of the the thrower, some authors have paid much year (Season 98-99) achieved by each attention to the displacement of the throw- thrower. er’s centre of gravity (CG) across the throw- A three-dimensional photogrammetric ing circle to try to understand the dynamics technique was used, filming the action with of the thrower-hammer system (Dapena, two Panasonic MS-5 video cameras (operat- 1986). Certain goniometric variables can be ing at 50 Hz), with a cube as a reference considered significant for the dynamic inter- system for 20 points distributed in the relationships of the system, such as those of throwing circle. After calculating the bidi- the knee of the leg that remains in the sup- mensional coordinates of the 21 body land- port position throughout the throw (Pozzo, marks from the 14 segments of the body 1987), and the angles of torque of the shoul- and the centre of the hammer head and ders in relation to the hips. these coordinates at 100 Hz through quintic The aim of the study was to collect data spline functions, the cameras were auto- from the world’s best performers for analysis matically synchronised using algorithms in order to discover the factors or criteria of developed by Gutierrez and Martinez efficacy used to obtain the best results. (2000). The theoretical basis for this syn- chronisation lies in knowing the error pro- Materials and method duced in reconstructing the spatial coordi- One throw was analysed of each of the nates of a moving point through the DLT top six finalists in the Men’s hammer event algorithms (Abdel-Aziz and Karara, 1971), Table 1: Subjects analyzed in this study with the results obtained in Sevilla99 Cham- pionships (Sev99-Result), the event analysed (Sev99-Analysis) and their best performance during 98-99 season (Season 98-99).

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