When physicists take an interest in sports it is common for them to analyze the actions on the field, court, or rink from a physics perspective. 

I am certainly a hockey nut, and while I would not say I am a physicist, I have some college level physics under my belt.  Despite this, analyzing hockey skating from a physics perspective hadn't crossed my mind until approximately twelve years ago. 

This is the story of the event that led me to do just that specific to hockey skating technique and to realize that hockey skating is missing an overall framework of understanding.  

During that spring of 2005, I had the opportunity to observe the front lines of a discussion among the world's hockey skating experts about the optimal technique for the forward stride. 

It took place in a banquet hall at a Sheraton Hotel in Novi, Michigan during the International Hockey Skating Symposium. It was a two-and-a-half day event featuring numerous strength coaches, skating instructors, and researchers.

For the bulk of the event, skating instructors preached the tenets of stride length plus a recovery (return of the foot underneath the body after a stride push) to the outside edge directly underneath the center of gravity of the skater.  

Then, in the final presentation of the event, Dr. Michael Bracko (Dr. Bracko's Website) presented evidence that the fastest skaters among us actually have a slightly shorter stride length than those just slower than them.  

His evidence also showed that these fastest skaters recover not to the outside edge underneath the skater's center of gravity but to the flat of the blade under the hip of the recovering leg. 

Before I get into what makes this interesting, I should mention that these instructors who were preaching stride length were doing what they should be doing. This is because the technique adjustment described above is a tiny detail that an instructor may bring to bear with a student who already has tons of very good things going for them with their stride. 

Plus, preaching stride length is a great way to help players understand many of the things that will improve their stride.

Instead, they were talking about it as the key concept in the stride they have their students ultimately work toward. The experts were consistent with this message throughout the event until that last presenter showed evidence that provided strong resistance to that idea. 

In other words, many of the luminaries of the hockey skating instruction world spent the event consistently stating something that appeared to be wrong according to the evidence provided in the final presentation.  

Let’s look at the evidence that was presented. It was the top two or three percentile of skaters who stood out. 

For almost all of the other skaters, stride length was in direct correlation with speed (meaning that more speed was accompanied by a longer stride in most all cases other than at the very top few percent) and this matches common sense as more distance down the ice per second (speed) would logically lead to more distance down the ice per stride (stride length). 

Why is it that it is only with the very fastest skaters where increased speed and increased stride length didn't show a strong correlation in the data? 

Among the fastest skaters something different is happening. 

A simple equation will help us understand this phenomenon.

Stride Length x Stride Rate = Speed

The truth is, we cannot go faster without producing more force, so this equation can be deceptive if used incorrectly.  With that said, it tells us that, if we want to increase speed based on this equation, we have a few options; increase stride length or increase stride rate, or both. One question that could come to mind is, which technique is preferred?  Traditional hockey skating instruction will tell you stride length is the answer.

Compared to Stride Length, Stride Rate is under-appreciated 

If you see a skater accelerate from a medium speed up to a high speed, what happens to their stride rate in order to create that acceleration? It almost always increases.  When we need to accelerate, we increase our stride rate, an interesting development.  

That is what these fastest couple of percentage points of skaters were doing as compared to the other skaters. Those top-end skaters have a slightly shorter stride length than the skaters just slower than them, but they had a greater stride rate. 

They were executing more stride thrusts in any given amount of time, and this led to greater overall forward horizontal force produced on average over time. You do that and you will be faster. Forward horizontal force production is the key to forward speed (and forward acceleration).

But, let’s understand that one can’t get an increased stride rate for free. If one is going all out, the only way to increase the stride rate is make the mechanics involved more compact. One can’t just move faster by trying harder in this case because the idea is that they were going at full effort in the first place. 

In the next part we will look at the mechanism that these athletes were using to push their stride rate to a higher level than their slightly slower peers.