I've worked on my running form for some time now with the goal of improving my running economy, and speed, and I've been working on building up my mileage, so I can maintain better form over long runs and perform better in distance races. The video below shows my running form, and I've added in some freeze frames and captioning to highlight some key aspects of my form that I have focused my efforts on.
More and more, experts agree that running better includes avoidance of "over-striding." Over-striding occurs when we reach well forward with our leading leg on each stride in an attempt to lengthen the stride and run faster. The problem with reaching forward is that we tend to straighten our legs out in front of us, so that our entire leg is pointed forward when our foot strikes the ground well out in front of our center of gravity, usually heel first (thus the dreaded "heel strike" which has gotten so much press lately).
Other issues related to stress and impact notwithstanding, landing with our entire leg pointed forward at foot strike results in our legs then absorbing some of our forward momentum as it flexes and we transition though to the next stride. The effects is a slight braking force that we then have to overcome on each stride.
No matter what our stride and foot strike look like, we all experience some amount of braking force, but if we avoid over-striding and our foot strikes the ground as we started it's rearward motion, we may be able to avoid some of the braking force, and run more efficiently--goes the theory. It's actually a pretty good theory, based on 1st Principles, so there is probably some truth to it.
So, here's the question: If I already run 180-184 strides/min, much like so many elite runners, and my speed is still somewhat lower than the elite runners, what can I do to improve my speed? Logically, my best option is probably to increase my stride length. But how so? I've already talked about why over-striding is undesirable, so it's probably not a good idea just to go out and try consciously to take bigger steps, right? Right.
The real solution isn't in trying harder to take bigger strides, but in developing the strength in my quads, hip extensors, and calves, and learn to take better advantage of the elastic recoil of my running muscles to absorb and return energy by contributing some additional "spring" to each step. In other words, my best bet is to increase my "air time."
So, I should go out and consciously try to bound upward a little on each stride? Well, no. The trick is to develop and use my strength to push off (with hip extention and elastic recoil coming into play) at just the right angle to optimize both the proportions of upward spring and forward thrust. If I do a good job of this, my form will look virtually the same as before, but the distance between my foot strikes will increase while I maintain the same 180-184 cadence I desire. So, I can increase my speed without over-striding, and with any luck, I can do so while making something close to optimal use of elastic recoil, to make more efficient collective use of my running muscles.
Making video recordings of myself running periodically can help with all of this. It's often difficult to sense exactly what is going on with our running form, and video can allow us to somewhat more objectively observe our own running, and provide the kind of feedback we need to make sensible adjustments to our running form.