The science behind kicking a field goal gives soccer style an advantage

Paradigm shifts in sports fascinate me, in part because they’re virtually always unscientific. Everyone is doing things one way, then a pioneer realizes that another technique simply feels better. While athletes can immediately choose between the old and the new, scientists spend years deciding whether the new technique is truly an advancement.

Consider the Fosbury flop. Prior to the 1968 Olympics, almost all high jumpers went straight at the bar, throwing one leg and their head over at the same time. When Dick Fosbury came along with his backward, head-first, facing-the-sky technique, Time magazine referred to it as “preposterous.” Even Fosbury’s own coach told the magazine, “I wouldn’t advise anybody else to try it.” That was right before Fosbury won gold and set an Olympic record. Four years later, most of the competitors used the Fosbury flop. It took researchers years to figure out the physics of why the flop worked so well.

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Now that football is in full swing, I’ve been thinking about the scientific explanation for another paradigm shift. Beginning in the 1960s, the “soccer style” of placekicking began to take over professional football. Younger sports fans might not remember the old straight-on style. The kicker stood directly behind the ball, creating a straight line connecting him, the football and the uprights. The holder placed the ball straight up, perpendicular to the ground. The kicker took a short step, then a full step as he swung his kicking leg straight back, then snapped it forward. His ankle locked, keeping his foot in an extreme flexed position as he walloped the ball with his toes.

Virtually everything about this technique is different from that employed by today’s soccer-style kickers. They approach the ball from the side, the holder tilts the football, and they strike the ball with the instep rather than the toes.

While the two styles of kicking coexisted for the better part of two decades, the soccer-style kickers won out.

Let’s take a look at the biomechanics of kicking, to see how and why the soccer style has taken over and whether the straight-on style has anything to say for itself.

First off, it’s not surprising that straight-on kickers could match, and sometimes exceed, their soccer-style colleagues.

“In a foot/ball collision, the ball goes off at about 20 percent faster than the foot is traveling,” according to Adrian Lees, a professor of biomechanics at Liverpool John Moores University in the United Kingdom. “However, this percentage can be increased or reduced depending on how rigid or flexible the foot is.”

Straight-on kickers lock their ankles, with the foot approximately perpendicular to the leg, which enables them to transfer the kinetic energy of the swinging leg to the ball very efficiently. Soccer-style kickers hold their foot at a more obtuse angle at the moment of impact, which means some of the leg’s energy is absorbed by the flexing ankle joint. Soccer-style kickers use a couple of tactics to overcome this disadvantage.