The Science Behind the Slap Shot

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Science of Slap Shot
Brian Poulsen

Ever wonder exactly what goes into a slap shot?

 

 

The slap shot. It’s one of the deadliest shots in hockey, and can reach speeds of over 100 mph. The video below delves into the science behind the slap shot. You can clearly see how much of the body is involved in the shot, as well as the considerable amount of stick bending. It goes without saying that the slap shot is quite complicated in terms of biomechanics.

 

The 6 Phases of the Slap Shot

  1. Backswing: The wind up before a slap shot, with the hockey stick up in the air behind the player
  2. Downswing: The motion of swinging the hockey stick down towards the puck
  3. Preloading: The bending of the hockey stick before the hockey puck makes contact with the blade
  4. Loading: The bending of the hockey stick when it is in contact with the puck
  5. Release: When the puck is released from the blade of the stick
  6. Follow Through: The continuous motion of the hockey stick towards the target

Since we all know what a slap shot is, let’s dig deeper into the biomechanics of the slap shot. There are many factors that contribute to the velocity of the puck during a slap shot; we’ve listed a few here:

  1. Puck Impulse
  2. Initial and final stick velocity
  3. Stick stiffness (composition)
  4. Amount of stick bending
  5. Force exerted by the player

In addition, the Preloading, Loading, Release, and Follow Through phases in the slap shot also contribute to the stick velocity, which in turn results in a change in puck velocity.

The amount of stick bending is very noticeable for a slap shot, especially one from an elite hockey player. This occurs in the Loading phase of the slap shot, which is initiated by the ground reaction force and downward pressure of the lower hand on the shaft of the hockey stick. The greater the amount of flex in the hockey stick, the more potential energy is built up and transferred into kinetic energy that allows the puck to propel straight into the net. Another factor that contributes to puck velocity of the slap shot is Puck Impulse. Important factors to consider are:

  • The amount of time the stick is in contact with the puck will increase the final velocity
  • The contact time is increased by the amount stick bending and the final moment of inertia
  • The rotation of the torso, shoulders, biceps, and forearms in sequence helps transfer momentum from greater moments of inertia to lesser ones

There is evidence that elite hockey players can create much greater maximum puck velocity in their slap shot as compared to recreational players (no kidding!). One of the main reasons elite players are able to generate much faster slap shots is that they are able to flex their hockey stick much more during the slap shot, which in turn increases the puck- and stick-contact time duration. This allows the hockey stick to accumulate greater amounts of potential energy, and then release it like a whip which helps propel the puck straight into the net.Blade-Puck Contact Time

As you can see from the above graph, there are substantial differences in hockey-stick bending, in addition to the recoil percentage that occurs in the slap shot between elite players and recreational players. The graph shows that the recreational player is able to generate 18.2% of the blade-puck contact time in bending, and less than or equal to 35.4% of the blade-puck contact time in recoil. Whereas, the elite player is able to spend 28.8% of blade-puck contact time in stick bending and 59.8% in recoil in blade-puck contact time. In addition, the recreational player isn’t able to generate shaft deflection.

For an elite player, the average blade-puck contact time during a slap shot is 38ms, whereas the recreational player is only able to maintain a blade-puck contact time of just 27ms. It’s obvious the recreational player has a much slower final velocity compared to that of the elite player, as the blade-puck contact time is much shorter.

CCM Jetspeed Hockey Stick Launch

If all this has got you feeling a bit down, don’t despair—we’re rec hockey players, after all! The video below will help you perfect (or at least improve) your slap shot technique.

From BPK201, an In Depth Analysis of The Hockey Slap Shot. Study conducted by Alan Jin, Kim Hilton, and Nicole Thomas of Simon Fraser University, Burnaby, BC, Canada.

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