Monday, July 03, 2006

The Six Stages of the Slapshot

Preperation: The player positions the puck in front of the skate closest to the target: on average, this location optimizes the amount of energy that will be transferred to the puck on the stick's impact. It might be advantageously altered, though, according to the niceties of a player's technique or his intentions on a given shot. Shifting the puck forward, for instance, might decrease energy transfer but will make the shot go higher. (Height is also a function of the angle of the blade relative to the ice as it strikes the puck; a player varies this by rotating the shaft.) Body stance also helps set a shot's direction and height. The leading shoulder is pointed in the intended direction of the shot. For a right-handed shot, turning the stance so that the lead shoulder points more to the left of the net will make the puck go higher and to the left; shoulder to the right aims the shot lower and to the right.

The Windup: The player draws his stick back by raising his posterior arm (the one furthest from the target) and rotates both his trunk and hips to raise the blade of his stick as far behind and above him as possible. The more the trunk, hip and shoulder muscles are stretched, the greater the force generated when they are contracted. The further the stick is drawn back, the greater the velocity of the shot -- giving players with longer arms and sticks an advantage. Nonetheless, a maximum windup may not be the best idea in many game situations. "The success of a shot is not only reaching peak velocity," says Hoshizaki. "There's a trade-off: the more time you spend winding up, the more time the goalie has to prepare. People like Brett Hull score a lot of goals because they have such a quick release."

The Downswing: The shooter rotates his hips, trunk and shoulders, causing the stick to accelerate forward and downward until the blade comes in contact with the ice approximately four inches (10 centimetres) behind the puck. Hoshizaki is still studying why four inches is the optimal distance, but believes that any less reduces the amount the stick can be loaded and any more risks breaking the shaft.

Loading the Stick: At this point, the shooter continues to apply pressure on the stick by pushing the lower hand against the shaft and holding the upper end of the stick close to the body. This causes the shaft to bow and thereby store energy. (A top player can make the shaft bow four to five centimetres.) The height of the lower hand on the shaft is critical. If it is too high, the shooter will not be able to bend the shaft enough to maximize energy load: if it is too low, not as much energy will be transferred to the puck. The best compromise position is set by a variety of other factors. "The right height depends on the strength, height and skill of the player," says Hoshizaki. This is the most important stage of the slapshot because so much of the velocity is generated here.

Impact: As the movement continues, the blade catches the puck, releases energy and accelerates the puck as it clears the ice. Ideally, the puck is struck by the heel of the blade, which is the "sweet spot" of a hockey stick: because it is closer to and in line with the shaft it offers more effective energy transfer. The further out on the blade, the more torque, or twisting force, there is. That's why players can take flick shots off the tip of the blade that rise quickly but lack the speed of shots taken at the heel. During this stage of the slapshot, the shooter rotates the shaft forward so that the blade turns over until it faces down toward the ice. This motion increases the acceleration of the puck by maintaining the force on it instead of letting it roll off an open-face blade.

The Follow-through: The player continues to allow the body to rotate and move forward so the stick moves forward and upward in front of the body. Not all the energy built up in the earlier phases can be transferred to the puck, so the player has to continue to move forward and absorb the rest to maintain his balance. If he didn't follow through fully, he would fall over or risk doing damage to his muscles. As in a golf swing or tennis shot, the follow-through helps shape the action phase (that is, the downswing, loading and impact stages) and is also a valuable teaching cue. If the follow-through is good, it usually means the action phase was completed properly.

From "How Hockey Works." Published in Equinox: January/February, 1994.