More than 40 sensors placed on 19 major joints of the body (and the ball) recorded the movements of the kickers as they stood behind the ball, took two steps, and kicked either to the left or of the right side of a goal. Diaz recorded 126 kicks, half to the left and half to the right.
Then he tested the data he collected against the suite of 27 potential indicators.
Twelve of the indicators such as the angles of the kicking foot, kicking upper-leg, and kicking shank were movements of a specific, or "local," area of the body highlighted by coaches and sports psychologists. Among them he found that two - the angle at which the non-kicking foot is planted on the ground, and the angle of the hips as the kicking foot swings forward are reliable indicators of kick direction.
The 15 indicators identified in a computer analysis of the kicks were so-called "distributed movements" patterns of coordinated movement throughout the body. Three of the "distributed" movements proved to be reliable early indicators, none of which appears to have drawn previous attention in sports literature.
Emerging evidence in the study of motor control has pointed to a significant role for distributed movements, Diaz said. He described distributed movement as a combination of movements developed over many repeated attempts to perform a task, in this case kicking in a particular direction.
"When, for example, you shift the angle of your planted foot, perhaps in an attempt to hide the direction of the kick, you're changing your base of support. In order to maintain stability, maybe you have to do something else like move your arm. And it just happens naturally," Diaz said. "If this happens over and over again, over time your motor system may learn to move the arm at the same time as the foot. In this way the movement becomes one single distributed movement, rather than
|Contact: Mary Martialay|
Rensselaer Polytechnic Institute