May 26, 2018

The Physics of Downhill Skating

The term downhill skating comes from the idea that it is easier to bike, rollerblade, or skateboard down a hill than up a hill. This is a feature of our physical world.

Most skating instructors focus on getting your balance first. Then pushing second.

Almost all power skating instruction centers around the idea of pushing. Even the name implies pushing: Power.

Power equals work over time. Implied in that is a measurable linear force. The foot pushing the ice away from you.

Downhill skating is a very different approach. I hypothesize that skaters like McDavid, Barzal, and Mackinnon have structural features that predispose them to learn these techniques. I don’t discount the fact that they also have the psychological characteristics to put in hours of practice.

Downhill skating uses shifts in body weight that leverages the rocker of the blade to create movement.

When a skater has forward momentum, and they tilt their skate, the rocker of the blade creates an arc that the skate follows. If a skater maintains their original body weight position (center of mass), the player will fall over because the forces acting on the player are not in balance.

If the skate tilts to the right, and body weight shifts to the right at the same time, the player’s forward momentum turns into centrifugal force. If the player maintains their skate position and body weight, the player will glide on an edge and remain in balance.

An added feature of this movement is that the player will accelerate in the direction of their weight shift. When I use the term acceleration I use it to describe a change in velocity. Velocity is different than speed because it indicates a direction. Speed does not. So the player’s “speed” may not increase, but the player’s acceleration changes. And you’ve always heard that hockey is a game of acceleration.

You might pause here and consider that power skating usually involves inside edge and outside edge holds. Instructors have different terms for these. For our purposes, we’ll call them inside and outside edge c-cuts. They do a good job teaching alignment of body and control over edges. Power skating instructors will use different footwork and edging patterns to increase the challenge. I think these are all good things.

These drills teach players to align their bodies to maintain balance while on an edge. But the only problem is that they generally don’t teach players how to do this in dynamic game situations. Nor do they encourage a translation from training to gameplay. I think that some players naturally get that translation due to structural features of their hips – and I think this explains the varied success of power skating instructors.

The footwork for a typical rush in the NHL looks something like this:

  • Crossover
  • 10&2
  • Crossover
  • Shuffle Step
  • Stride
  • Shuffle Step
  • Corkscrew
  • Anchor
  • Soft Hip
  • Hip Scissor
  • Corkscrew

Each movement uses the principle of body weight shifts and using the rocker of the blade. But each movement is incredibly dynamic. At any moment, that movement might need to morph into 4 other movements depending on where the defenders move. So each movement in this chain needs to provide options.

Few players know these positions. Even less can transition between them smoothly.

A factor in transition is muscular tension.

When you are slightly out of balance or out of alignment, your body contracts muscles to bring it back into alignment. A good way to test this is to stand up and relax all your muscles. You’ll notice that your skeleton naturally aligns. If you move out of balance, your muscles need to contract (generate tension) to move back into alignment. If you hold an out of alignment position, your body must maintain tension to hold yourself there. Think of a plank.

Helping players find alignment in these positions and movements is critical to reducing tension.

Reducing tension in your movements provides more optionality and quicker reaction times.

When you contract your muscles, it is a graduated response. To contract a muscle, your brain talks to motor neurons. Some motor neurons attach to a small number of muscles and have fine control. Other motor neurons attach to larger numbers of muscles and generate more force – but give up fine control.

Larger motor neurons generate more force, but they also take longer to generate that force – and to turn off the force.

If you are in a position that is out of balance and you need need to generate tension in your muscles to maintain it, you reduce your ability to be reactive. More tension means that you’re recruiting more motor neurons that keep you in your movement track. If you have more tension in your muscles, it takes more time to relax your larger motor neurons and then fire new ones. These milliseconds are critical in high-pressure situations.

The most common “Tension Blocks” I see with players are:

  • They don’t use their outside edge properly
  • They hold their ankles stiff
  • Their hips don’t move to allow body weight alignment
  • They externally rotate their femurs

The idea of the Downhill Skating System is to teach players the postures and movements that reduce tension in their skating. This leads players to be able to smoothly shift weight over their edges to accelerate. I’ve included a list of other articles on the Downhill Skating System for your reference here.

If you want to learn how to apply the Downhill Skating System Principles to forward striding, you can read this article.

If you want to skate more smoothly, you can read this article.

If you want to improve your edges, you can read this article.

If you want to skate faster in a game, you can read this article.

If you want to know how McDavid could skate faster, you can read this article.

The intention of this article is to help you understand how the best skaters in the NHL move. If you’d like help implementing this knowledge, I created a video course called the Downhill Skating System. You might want to take the Downhill Skating Style Quiz that we created to see your biggest opportunity to learn Downhill Skating.

Thanks for reading today!

-Jason

 

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