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How to read goalkeepers with science

2013/06/18

Prof. T. Asai of Faculty of Health and Sport Sciences, and his research group have found a scientific explanation to how soccer goalkeepers manage to stop an opponent from scoring a goal.

To date, research into soccer player mechanisms have focused on factors such as kicking or dribbling.  This study has aimed to look at the mechanism behind the goalkeeper, specifically when goalkeepers make a dive to save an incoming ball.

A team of researchers at the University of Tsukuba, lead by Assistant Professor Keita Matsukura and Professor Takeshi Asai, had studied how 11 university soccer club goalkeepers (average height of 178.4cm and an average weight of 71.2kg) move their bodies when they went in for a dive to save an opponent’s attempt at goal, and recorded their actions using a 3-dimensional automatic analysis device called the VICON.

They found the leg furthest from the ball provided most of the power, but more importantly the leg closes to the incoming ball would control the direction that the goalkeeper would jump.  How a player balances these two factors might have significant effects on the game.

Leg mechanisms also changed depending on the height of the shot.

A high shot saw the goalkeepers use the leg behind their center of gravity as their power source, and their other leg as the controller, but this changed later on when the front leg would also turn into a power source.  To put it into perspective, if a goalkeeper were a car, it would start off as a front engine car, and then change into a 4WD car.

If the goalkeeper could not jump, such as when the shot is low, the back let would remain as the power source, but the whole body would twist onto its side.

The results from this study have shown how much the legs are responsible for the resulting dive, and can be applied when training goalkeepers, and might be a new way to enjoy watching soccer.

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Goal keepers’ diving motions and the ground reaction force.

Original Paper

Keita Matsukura and Takeshi Asai, Characteristics of force exerted by soccer goalkeepers during diving
motion. Japan J. Phys. Educ. Hlth. Sport Sci., 58, 277-296, June, 2013.

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Prof. T. Asai

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