Development of a System to Measure Radius of Curvature and Speed of Hammer Head during Turns in Hammer Throw

Abstract

The aim of this study was to compare the radius of curvature and the estimated head speed as measured by sensors attached to a hammer with those calculated by video image analysis. The participant was the Japanese record holder(83m47). He threw a hammer with sensors which measured the force exerted along the length of the hammer cable using a tension meter made of a metal plate to which strain gauges were affixed, and the angular velocity perpendicular to the hammer cable using two IC accelerometers whose axes were aligned together with the hammer cable. The radius and speed obtained using the sensors were similar to those obtained from video analysis in values, but were slightly out of phase. This is because measuring the angular velocity by sensors eliminates translational motion and only produces results for rotational motion. The length of time required to obtain these results was shortened by the use of a hammer with sensors. Therefore, the system using sensors attached to a hammer will enable athletes and coaches to interpret the data about each throw while it is still fresh in their minds.

An analysis of the relationship between the linear hammer speed and the thrower applied forces during the hammer throw for male and female throwers

“…The general trends of the traces of hammer speed and cable force (Figures 2 and 3) are similar to those previously observed in the literature (Dapena, 1984;Bartonietz et al, 1988;Murofushi et al, 2005;Brice et al, 2008) with the males obtaining higher cable force magnitudes than the females. The trends of the traces of tangential force (Figure 4) are similar to the trend reported by Bartonietz (1994), with the polarity alternating between being positive and negative and there being a single fluctuation within each turn.…”

“…This type of feedback would allow the coach and athlete to formulate a basic assessment of an individual's performance characteristics. For example, previous studies in the literature have shown that generally each peak in hammer speed and cable force is clearly greater in magnitude than the previous peak (Dapena, 1984;Bartonietz et al, 1988;Murofushi et al, 2005;Brice et al, 2008). In this current study this type of behaviour was observed in all but one female (four turner) participant's data.…”

“…Methods have been developed that allow direct and accurate measurement of the magnitude of the cable force in the training environment and also cause minimal change to the weight of the hammer (the mass of a strain gauge is added to the system which is negligible compared with systems that added 1.3 kg (Hwang & Adrian, 1984) and 0.37 kg (Murofushi et al, 2005)) and allow immediate feedback on the trend of the cable force (Brice et al, 2008). This type of feedback would allow the coach and athlete to formulate a basic assessment of an individual's performance characteristics.…”

“…Recently there have been increasing amounts of research into the acceleration mechanism of the hammer (Maheras, 2009;Murofushi et al, 2005Murofushi et al, , 2007Ohata et al, 2010). Murofushi and colleagues (2005) developed an instrumented hammer that provided information on hammer speed and radius of curvature in a short amount of time.…”

Evaluation of Hammer Throw Technique for Faculty of Physical Education Students Using DartFish Technology

“…We would find that the half of the diameter increases in (SS), and decreases in the (DS) and has an effect on the velocity of the hammer. (18) The relationship between initial and final angular velocities is one of the important factors in the throw movement. Throw technique is effective when a player increases the acceleration from one phase to another to enhance the angular velocity, which transmits in turn to the hammer velocity.…”