Notice the differences in running (top) vs sprinting (bottom) activation patterns?

This picture (along with the MIchaud muscular firing pattern ones) are becoming some of my favorite ones to talk about. I just stare at them and look for differences and similarities. 

Check out that the abs do not seem to fire in running (in this study at least), but do in sprinting. Note also that most muscles fire longer (and we wil assume harder) during sprinting. Also check out the peroneals, which fire just as the foot touches down in sprinting, probably to make up for the instrinsics not firing, and assist in creating a rigid lever for push off. 

from: Mann et al 1986

Usain… Again!!! How good are your powers of observation?

Take a look at this video again. Yes, we have shown it many times before. It is from a 2001 race in Monaco.

These are all incredible athletes. What can we note about the fastest of the fast?

  • Most of them have excellent hip extension (ok, the gent immediately to Usain’s right does not appear to be optimal)
  • the fastest of the pack have a upright head posture with the neck neutral or in slight extension (gents in lanes 1, 3 and 6; notice the head forward posture of the others)
  • minimal heel rebound (see our last post on this here)
  • minimal torso motion (note the increased torso motion  with arm swing of the gents in lanes 1, 3, 4 and 5)
  • symmetrical hip flexion, with the thigh parallel or nearly parallel to the ground in float phase
  • what else?

Watch it a few more times. It took us a while too…

Really, go watch it again…

Did you see it?

Watch the vertical oscillation of the runners. At this level (or any level for that matter), outside of improving biomechanics and neuromechanics, there are really only a few things you can do to run faster. One is to have a faster cadence and another is to have a longer stride length. You can control both, but if not done concurrently, one gets better at the expense of the other.

If your cadence is slower and you try and increase stride length, you increase your vertical oscillation (ie: how much you bounce up and down). Note the handrail at the far side of the track. It makes a convenient marker for vertical oscillation. Watch this bar and watch the video again. Usain and the gent in lane 6 (Nesta Carter) have little vertical oscillation compared to the rest of the pack. Note also the close finish. difficult to say if Usain’s knee or Carters foot crossed 1st. Usiain’s time was 9.88 and Nesta’s 9.90.

Decreased cadence = Increased vertical oscillation = Less horizontal motion = Slower speeds

How about watching this video a few more times and telling us what else is up?

The Gait Guys. We are trying to help you improve your powers of observation while stretching your mind. Are we succeeding? We hope so!

Ivo and Shawn

Ankle Dorsiflexion: Even in sprinters who land on the forefoot often heel strike, a retrograde strike if you will.

Many people think of heel strike followed by midfoot/tripod contact phase followed by ankle dorsiflexion, aka ankle rocker.  Heel strike is normal in the walking gait cycle. In some runners, depending on foot type, strength, flexibilty and several other factors, heel strike may be considered normal and may be essential for normal injury free mechanics. However, in recent years we tend to see the media and research investigate a midfoot or forefoot strike pattern. If you have been here with us on TGG for a year or 2-3 you will know we are big advocates of a midfoot strike pattern for several reasons which we will not go into again in this article. (Feel free to SEARCH our blog for MIDFOOT strike articles).  

However, one rarely sees anyone or any source talking about the retrograde heel contact when forefoot strike patterns are used.  Here, in this video, you can see several of these top level athletes who are trying to go forward at top end speed, but who are tapping the heel down on many loading responses. This can be thought of as a retrograde movement and could in a biomechanical way of thinking be considered non-productive. In other words, they are trying to move forward and yet the heel is touching down which is a backwards movement. This point can be argued but that is not the point of this article. The point that we are trying to make is that in order to drop the heel down, and especially if the heel touches, that the runner had better have sufficient ankle rocker/dorsifleixon otherwise the arch may be asked to collapse via excessive pronation (to perform the heel tap) which will drive an internal spin movement when the leg is supposed to be externally rotating to a rigid supinated foot for propulsive toe off. This negative scenario is a huge power leak for a sprinter, or any runner for that matter when they are ramping up speed.  

So, why does this happen ?  Well, for some it can help to load the posterior mechanism, the gastrocsoleus-achilles complex for conservation and power conversion.  It also enables more hip extension and thus more gluteal function. Longer stride means more efficient and greater arm swing which is a huge accessory power source for a sprinter. This also lengthens the stride, they feed off of each other. There are many benefits, if you have sufficient ankle rocker range in the ankle to begin with.  In some runners who do not have the requisite ankle rocker range, you may often see the increased foot progression angle and external limb spin and/or the dreaded adductor twist of the heel (aka  abductory twist of the foot).  These are strategies to get more hip extension and more gluteal function without finding it via the ankle dorsiflexion, where you want to see it.  Remember, the body is a brilliant compensatory and substituter. If the body cannot find a range at one joint it will find it at the next proximal or distal joint. And when that loss is at the ankle, motor patterns options dictate you either find it at foot pronation or hip extension.

Maybe, just maybe we should have called this blog article “Can you hold the foot tripod all the way through the stance phase, even through retrograde heel touch down ? If you cannot, trouble could be on the horizon. ”  But that is a really dumb title.  

Shawn and Ivo

the gait guys

Some Biomechanical Facts on Oscar Pistorius: 400 m London Olympic Games

Following Saturday’s 400m men’s preliminary heats Jere Longman’s wrote an article in the NYTimes entitled “Pistorius Advances to Semifinals”. In it were some interesting facts. Here is the link to the article. 

Ever since Pistorius’s shut out from the Beijing Olympics scientific and legal debate has continued about whether his prosthetic legs gave him an unfair advantage over sprinters using their natural legs. However, as we all knew, this time around would different in London 2012. Competing on carbon-fiber prosthetics called Cheetahs, Pistorius was going to get his chance and in the process further the debate on what is considered able and disabled.

Prior to Beijing the I.A.A.F. said Pistorius’ carbon-fiber blades violated its ban against springs or wheels that gave an athlete a competitive edge over able bodied athletes. The prosthetic legs allowed him to run as fast as elite sprinters while consuming less energy, the governing body concluded. None the less, the debate has continued over the past few years since Beijing pertaining to where to draw the line between fair play and the right to compete. In 2009 in The Journal of Applied Physiology a study concluded that Pistorius could take his strides more rapidly and with more power than a sprinter on biological legs.

An acquantance of ours who we talk to from time to time, Professor Peter Weyand at SMU Locomotor Performance Laboratory in 2009 looked at Oscar Pistorius-type carbon fiber Cheetah blades a little more closely. In his study (referenced below), in the Journal of Applied Physiology, he conducted three tests of functional similarity between an amputee sprinter and competitive male runners with intact limbs: the metabolic cost of running, sprinting endurance, and running mechanics. What he found was:

  • the mean gross metabolic cost of transport of the amputee sprint subject was only 3.8% lower than mean values for intact-limb elite distance runners and 6.7% lower than for subelite distance runners but 17% lower than for intact-limb 400-m specialists
  • the speeds that the amputee sprinter maintained for six all-out, constant-speed trials to failure were within 2.2 (SD 0.6)% of those predicted for intact-limb sprinters.
  • at sprinting speeds of 8.0, 9.0, and 10.0 m/s, the amputee subject had longer foot-ground contact times ,shorter aerial and swing times and lower stance-averaged vertical forces than intact-limb sprinters [top speeds = 10.8 vs. 10.8 (SD 0.6) m/s].

Weyand concluded that running on modern, lower-limb sprinting prostheses appears to be physiologically similar but mechanically different from running with intact limbs.

Longman’s article listed some of the other facts that have come up in recent years, facts that led to the eventual acceptance of Pistorius in London 2012’s Olympic events.  We have not captured these references specifically (yet, but we will) but in the mean time to keep this blog article timely, lets look at some of the other facts that Longman mentioned in his NYTimes article:

  • While calf muscles generate about 250 percent energy return with each strike of the track, propelling a runner forward, Pistorius’s carbon-fiber blades generate only 80 percent return, Gailey said.
  • Given that Pistorius has no feet or calves, he must generate his power with his hips, working harder than able-bodied athletes who use their ankles, calves and hips, Gailey said.
  • And because the blades are narrow and Pistorius essentially runs on his tip toes, he pops straight up out of the blocks instead of driving forward in a low, aerodynamic position for the first 30 or 35 meters, making him more susceptible to wind resistance, Gailey said.
  • Compared with runners with biological feet, Pistorius also must work harder against centrifugal force in the curves, and his arms and legs tend to begin flailing more in the homestretch, costing him valuable time, Gailey said. His stride is not longer than other runners, as many presume, Gailey said. “It’s not like he’s bouncing high with a giant spring,” Gailey said.
  • The blades “basically allow him to roll over the foot and get a little bounce,” Gailey said, adding: “The human foot operates like a spring, and his feet operate like a spring. But the human foot produces more power than the blades do.”

There is an abundance of interesting information here. We will likely return to some of these topics and facts in the future, but in the meantime we say that everyone has their own demons and deficits. We all have injuries and limitations we have to cope with, in life and in sport. So where the line gets drawn will always be a blurred. This debate on this specific case with Pistorius could go on for years and never reach an agreeable conclusion as to a fair playing field. So, let the games begin and may the best man or woman win, with his or her demons and deficits in tow.  Good work Oscar. Thanks for the inspiration.

Shawn and Ivo, The Gait Guys

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We found 3 other journal articles on Pubmed on Oscar.

  1. Enhancing disabilities: transhumanism under the veil of inclusion? Van Hilvoorde I, Landeweerd L.   Disabil Rehabil. 2010;32(26):2222-7.

  2. Oscar Pistorius, enhancement and post-humans. Camporesi S. J Med Ethics. 2008 Sep;34(9):639.

  3. By designing ‘blades’ for Oscar Pistorius are prosthetists creating an unfair advantage for Pistorius and an uneven playing field? Chockalingam N, Thomas NB, Smith A, Dunning D. Prosthet Orthot Int. 2011 Dec;35(4):482-3.

  4. J Appl Physiol. 2009 Sep;107(3):903-11. Epub 2009 Jun 18.

    The fastest runner on artificial legs: different limbs, similar function?