Let's do a little thought experiment first:
So you're cooking pasta after a long day at work. Your mind is still buzzing from all that happened during the day. You are not paying much attention to what you are doing and you accidentally place your hand on the stove that you didn't think was already hot. What would you do?
We can pretty much agree that you want to get the hand off from the stove as quick as possible for it to not get burnt. And I'm guessing you would not first press the hand hard against the stove to only then take it off? So let's just agree that you would, as a reflex, PULL the hand off from the stove as quick as possible, because the longer the hand is on the stove the more likely it is to getting burned, right? You pull the hand off because that's the quickest way of getting it off.
That leads us to the subject of......
Ground contact time and its correlation to running efficiency and speed
There may be a lot of things under discussion and a lot of misunderstandings happening amongst the running community, but one thing that we can all agree on and that's been proven to be correct through numerous studies is that great runners spend less time on the ground and more time in flight. So in other words, their ground contact time (GCT) is shorter that the times of some not-so-great runners.
Researchers from Ryukoku University in Japan examined the running gait of elite half-marathon race athletes and videotaped 415 runners as they passed the 15km mark. As they studied the tape to gather measurements of ground contact time for each runner, they observed a strong negative correlation between ground contact time and speed. The feet of the fastest athletes, spent the least amount of time on the ground.
What is your goal as a runner?
As a runner, you most probably want to move forwards? That's your ultimate goal right? So why should you be concerned about your Ground contact time?
Here I'll explain you that as simply as possible.
Firstly - When your foot is in contact with the ground during running, you are not moving forward. You are only moving forward during the flight phase of the running gait. So the more time you spend in the air and the less time you spend on the ground, the faster and more efficiently you run.
" Ground contact times were ~10.0% shorter (very large effect) than in previously published literature in elite runners at similar speeds, alongside an 8.9% lower oxygen cost (very large effect). These results provide evidence to hypothesise that the short ground contact times may contribute to the exceptional running economy of Kenyan runners."
- A Study concluded by a group based in the University of Cape Town, published in The Journal of Sports Sciences: https://www.ncbi.nlm.nih.gov/pubmed/27157507
Secondly - the longer your leg is loaded with the weight of your body, so the longer it stays in contact with the ground, the more increased is your risk for potential injuries. You will not get injured in the air right?
" We conclude that subtle increases in step rate can substantially reduce the loading to the hip and knee joints during running and may prove beneficial in the prevention and treatment of common running-related injuries.
Effects of Step Rate Manipulation on Joint Mechanics during.... Available from: https://www.researchgate.net/publication/44803486_Effects_of_Step_Rate_Manipulation_on_Joint_Mechanics_during_Running[accessed Apr 20 2018]. "
Pulling Vs. Pushing
So let's go back to our little thought experiment at the beginning of this text.
We agreed that you would pull the hand off from the stove to get it off the heat as quick as possible, right? You would do that without thinking, as a reflex to the heat that you would feel in your hand.
Almost the same applies to running. We could simplify the running movement to as simple as:
" Pulling the leg up from the ground as a reflective response to the foot contact to the ground "
Try moving forward by fully extending your leg and pushing off and then try moving forward by removing your foot off support by pulling it up. Which one is easier and faster?
We've only scraped the surface here to what it comes to running technique, but we need to understand the "why's" and "what's in it for me's" for to really be ready to make a change.
Now we understand that the fastest and most efficient runners in the world have the shortest ground contact times and that the fastest way for us to get the feet up from the ground is by pulling can we start our journey towards becoming, not just better, but healthier runners.
You may have the hips of steel and buns perfectly shaped like little peaches, but it all doesn't really matter if you don't improve your movement efficiency first. Trying to push off instead of focusing on simply pulling the foot from the ground and your simply just wasting your energy and strength in stopping yourself. Think how fast you would be if you used that energy towards moving forwards?
These box drills may also be helpfull with starting to feel the difference between pulling vs. pushing. Try first to push yourself off from the box and move forwards. Try to then fall of from the box and pull your leg up from the ground as you feel the foot touching the ground. Did you feel any different?
PS. I've just opened up my newest online program of 12 weeks that is focused on improving running speed and efficiency. Let me know if you are interested :) https://skillbasedrunningcoaching.trainerize.com/contact.aspx