Observing the Kinetic Chain
While most countries saw their sport-science research nearly dissapear after the cold war ended, a united Germany continued with the same determination ever since and have pushed out new studies with regularity. Just last month, an Egyptian doctoral student Marwa Sakr completed a doctoral dissertation at the Universität Konstanz in Southern Germany focusing solely on the biomechanics on the women’s hammer throw. After hearing about her initial plans two years ago, I was eagerly awaiting the results.
Sakr’s research in many ways was an extension of Koji Murofushi’s research from several years ago. She created a device similar to Koji’s to help measure the energy throughout the throw. But the focus of her work was not simply measuring the kinetic energy levels throughout the body and hammer during the throw, but also to look at how the energy moved sequentially through the human body by looking at correlations between the energy levels of different parts.
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This is kind of tough. Did she do one in German?
Never mind, much better translation in section 2.
Great stuff! I did have a question though, previous studies have indicated that women have a longer double support phase than men do, particularly through the entry due to the sheer weight of the implement and the need to counter. If this is in fact the case, wouldnt it conflict with the ability to match, apples to apples, a study on men and a study on women? I would hesitate to believe that though the low and high point may correlate, the same body position and catch degree could be achieved. I could be mistaken, I am basing this off a study from ’96, but I wonder how an earlier or later double support phase in either the entry or catch could potntially effect ones ability to accelerate the ball…and if consideration to gender could potentially change the research itself before blanketing people with the oh so dangerous “this is completely correct” conclusion.
Most of the analysis I have seen recently show that the double support phase is about the same length for men and women. The main difference is that the top men both lift off their right foot and land early. This may well have an impact on translating the results to a broader conclusion, as do other factors with impacting the difference between the men’s and women’s hammer throw. I would also like to see if a women like Lysenko might have different results. Heidler and Klaas both use the same technical model and Lysenko’s model is more like those used by the top men. In any event, the tools used to measure these throws could be used in the future for more studies on other throwers. Hopefully this is just the starting point.
Good Stuff! I think the studies reinforces two principals of throwing in general.
The first one is that throwing consist of building giving kinetic energy to a whole composed of two parts- thrower and implement- the thrower of greater mass suddenly decelerates thereby decreasing sharply his/ her kinetic energy that is transferred to the implement. this is true of all throws. Hammer throw is different in that it happens every turn.
The second one is the very true “move the hammer not your body”. increase in HHKE go in hand with decreases in BKE. Once the system is in movement decreasing BKE yield faster hammer head. Which goes to show that hammer throw is not about rotation, it is not about spinning!
It was nice to find some striking similarities with the Murofushi study. mainly the use of right foot/ left foot and the essential asynchronous rhythm of hammer and thrower center of mass.