HOCKEY SKATE SMACK-DOWN


In the summer of 2012, I was asked if I could retrofit my technology to hockey skates for a research study. The philosophy behind the design of conventional hockey skates is closely aligned with that of ski boots; envelope the foot with 2 quarters that wrap the sole over and about the foot and support the foot and ankle. Some skate technologies allow portions of the skate quarters to be custom-moulded to the shape of the user’s foot and/or ankle.

One cannot go into a skate shop today without encountering the ubiquitous custom insole device and with it a sales pitch that claims that buying a new skate without a custom insole is a waste of money. Consumers are typically told that without a custom insole a skate lacks the foundation the foot needs for optimum performance and precise control. The generic insole that comes with a skate is simply inadequate.

The ‘foundation’ sales pitch infers that, like a building, the foot needs an orthotic or custom insole to provide a foundation. But it conveniently omits the fact that a foundation requires good ground (reaction force). Before I retired, I was a manager of building inspections, having been a building inspector for 25 years. The primary element in a good foundation is adequate ‘soil-bearing pressure’. This is another way of saying adequate ground reaction force; adequate being equal to or greater than the load imposed on it. You cannot support a building on quicksand, no matter how solid the foundation. And you cannot support the foot without a solid base of reaction force under its load-bearing points. This can only exist when the vector of the resultant force acting on the COM of a skier is aligned as described in PLATFORM.

Each sport has its own cultural preferences. In skiing, the default preference is the buckle boot. In skating, especially hockey, the default preference is laces. In consideration of an established bias towards laces I elected to design a simple, low-cost system that could be easily retrofit to a conventional skate and tensioned with laces. In about 15 minutes I designed a system  that attaches to a conventional skate in the front two (toe) eyelets and is tensioned using the existing laces. The system was simple in design and economical to produce. The sketch below is my original design that I used to make a crude mock-up from.

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The photo below shows the carrier frame formed from a piece of aluminum tubing.

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Here is the system. The Velcro on the front end (under my fingers) is to attach the shin tongue to.

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This is the shin tongue. The format is based on the same one I use for my ski boots.

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Here is the skate with my technology retrofit to it.

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All I had to do to install my system was to remove the existing tongue and insert 2 screws into the system through the eyelets. This was the easy part. The hard part was correcting what I consider to be impediments to foot function in the design of conventional skates. I call these impediments ‘footwear noise’ because the random manner in which they affect foot function makes it impossible to predictably influence performance of the foot-lower limb system. Modifications included expanding the width of the forefoot, cutting away and removing portions of the liner that were impeding joint movement and, most important, making the sole of the skate that the foot sits on dead flat while maintaining the stock ramp angle. The lower limbs have 3 degrees of freedom for a reason. Interfering with the dynamics of the arch of the foot and the multi-axial joint system of the ankle complex runs the risk of confounding neural data and the simultaneous joint actions needed to coordinate muscle activity for balance synergies.

As a reference, in a side-to side comparison of a conventional skates where one skate has incremental improvements and the other skate is its predecessor, the normal improvement seen in a series of metrics is typically <1%. An improvement of several percent would be exceptional.

I shipped the skates I had retrofit to the University of Ottawa. Five competitive hockey players were used for the study. The subjects own skates (OS) were compared to the skates using my technology (NS). As far as I know, no modifications of any kind were made to the new technology skates. The study was done by Marshall Kendall (Tekscan Canada), Katrina Zanetti and Blaine Hoshizaki (head of the Neurotrauma Laboratory at the University of Ottawa). It was presented at the 18th annual Congress of the European College of Sport Science in Barcelona, Spain: 26th – 29th June 2013, . A link to a PDF of the poster presentation appears below.

Final version -Barcelona skate poster

The graphs show OS (skate) and NS (new skate). The insole pressure maps were not labelled. The left pressure map is OS, the right map is NS. The OS map suggests that the arch is supported.

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For some reason the colours of OS and NS bars exchanged from Graphs 1&2 to Graph 3. In order to accentuate the degree of improvement of new skate over old skate I have extended the OS bars in the graph below  to show that improvements in some subjects >200% and was not less than 150%. This is particularly significant because the new skate is compared to the skaters own skates which they have adapted to.

Skate Forces