In parts 1 and 2 we looked at a skating technique adjustment that led to more speed, a slightly shorter stride length, and a greater stride rate. While extolling the virtues of this adjustment we knocked stride length off of its metaphorical pedestal as the key metric in excellent skating technique.

While the rumors of stride length's demise may have been greatly exaggerated (as stride length is still a hugely important concept that skaters should value in many ways), dethroning it does leave room for the true king of hockey skating concepts. All hail Knee Bend! Long live the king.

Readers of parts 1 and 2 would remember discussion about how, in the forward stride, forward horizontal force production is what it all boils down to. 

Wouldn't that make that the king? It would... if we were looking to focus on the result that we are trying to produce. But, what we are talking about here is a question of how we can generate that result (how we can produce maximum forward horizontal force). 

Knee bend is the single most important variable that helps us achieve that goal.  And knee bend is so important, it makes the abbreviated recovery strategy from the previous two parts seem downright trivial.

Increased knee bend has an effect on two key stride metrics which lead to speed. This dual effect is what makes deep knee bend such an important component of the high-performance skating stride. 

In this part of the article, we will delve into “increased extension length”. 

In part 4, we will look at flatter extension force direction. Deeper knee bend creates the possibility for both.

To understand extension length, it helps to use the skater's body as a reference point from which to take our measurements.  

When we measure stride length, we are talking about the distance down the ice that a player moves during each stride. To take this measurement, it requires us to use the rink to establish a baseline from which we take our measurements. 

In other words we are measuring relative to the rink. But using this, it is hard to learn much about the effects of knee bend. For that we should use the skater's body as the central point that we measure from even though the skater would be moving around the rink.

Using this perspective which treats the body as stationary, we can talk about extension length in the simplest terms. Extension length is the distance across the ice that the player pushes the skate away from the spot on the ice under the center of the body. 

At the beginning of this extension, the skater's leg is at a maximally bent position and their skate is very nearly underneath the body. At the end of extension, the leg is (ideally) straight and the skate is out away from the body. 

In between, as the skate moves away from the body, the skater's muscles are applying the propulsive force that we so covet to push the body forward. 

Extension is the part of the stride where we push ourselves forward so it stands to reason that more extension length would lead to more force and more speed.

What does deeper knee bend mean for extension length? 

Imagine a person standing straight up with both knees locked straight. How far to the side along the ground can that person reach with one leg with all of their weight on the other leg and neither knee bent? If you don't allow the pointing of the toe, the answer is zero distance. 

The only place that foot can touch the ground would be right next to the other foot because with both legs straight, bringing one leg to the side means you can no longer touch the ground with that foot. This ultimately means that with zero knee bend you can achieve zero extension length.

Now, if we allow the knee of the support leg to bend and then reach out to the side with the other leg, how far out can we tap the ground with the leg that is reaching out? 

We assume that the leg that is reaching out is locked straight as this gives the maximum outward reach.  Now the answer is dependent on one key factor, the height of the hips.

The closer the hips are to the ground, the further out along the ground the foot on the extended leg reaches. This spot along the ground where the foot touches is the point of maximum extension and the bigger that maximum the greater extension length we can have. So one huge benefit of greater knee bend (and the lowering of the hip joints that it creates) is an increased extension length.