Stride length and range of motion
Understanding the difference between stride length and range of motion continues to be an area of confusion that has been difficult for many of my students to overcome. All too often in my clinics, I find that I need to keep coming back to this point, to clarify the biomechanical and psychological differences between these two properties.
I can only imagine that this misunderstanding arises from our collective attachment to the existing paradigm of what running “looks” like, or the “exo-view” of running. This “exo-view” is so engrained in us, that I am often surprised to find that my students, despite having demonstrated a much deeper level of understanding of the elements of proper running technique, stare blank at me when I begin discussing with them that the real meaning of stride length has nothing to do with how wide you throw your legs to move forward.
The biomechanical and psychological difference between these two properties, is at the heart of understanding why reaching with the leg forward or extending your leg far backward has nothing to do with how far you travel as you change support from one leg to the other.
The biomechanical essence of stride length has to do with the traveling distance of the GCM from one support to the other, where the relationship between the point of support and the GCM is significant. The length of the running stride is defined as a distance between touching points of the same foot. Therefore the stride length is the distance between GCM on two sequent supports on the same foot. The artificial part, when the foot position happens to be ahead of the GCM point, is that it looks like it gives us a longer stride length, but in actuality this is the very action that causes us to brake or stop movement. The cost of “increasing the stride length” by letting the foot go ahead of the GCM is dramatic.
If we think of movement as a process of falling and using gravity as a propulsive force, any interruption of this will only be an interruption of the movement itself. So where is the sense in putting any effort into the legs leading beyond this point?
Range of Motion
“The Range of Motion”(ROM) should represent only one thing: the space covered by the extremities due to the necessity to change support. ROM is necessary only to change support. Within the time frame through which we are falling and traveling in the air to the next support, we only need a minimum amount of space and time to pull the foot up back to its position under the body.
With the increase of speed, pulling efforts also increase due to this speed requirement and the foot goes through a bigger range of motion up and down only because of the momentum that we create from this pull. So the range of motion from this point of view is the result of speed, its byproduct as opposed to an artificially created empty move that is actually braking forward movement, not responding to it.
So the greater “range of motion” is the result and function of speed and not the “creator” of speed.
We have to keep ROM within the space where we can maintain cadence. Any deviation of ROM from our ability to maintain cadence/ falling is unnecessary and only interrupts the cycle of movement and throws it off.
The psychological essence of stride length is that we should not have any images and commands, nor concerns with how to “develop” or keep it during the run, because it is a byproduct of speed. Speed, as you know, itself is a byproduct of degree of falling and cadence.