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Faster, higher, no longer

Discussion in 'Biomechanics, Sports and Foot orthoses' started by wdd, Sep 14, 2012.

  1. wdd

    wdd Well-Known Member

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    I have just read an article in 'The Economist', (August 4th-10th 2012), entitled Faster, higher, longer, which suggests that sprint and athletic performance generally can be improved by up to 30% if the foot remains on the ground 0.05s longer, during the stance phase, to give the relevant muscles time to contract maximally.

    How would running have to change to allow the foot to remain on the ground for an extra 0.05s per step while reducing the time per step by 30%?

    Could it be accomodated within a conventional running style or would it need an innovation, in running style, equivalent to the Fosbury flop?

    Keeping within the current rules for running, how would you attempt to modify running training, style, equipment, to make use of this extra 0.05s, potentially available each step for muscle contraction, to improve athletic performance?

  2. Bill:

    I wouldn't trust an article on running biomechanics that was published in "The Economist".
  3. Sicknote

    Sicknote Active Member


    The strongest predictor of top sprinting speed is ability to get off stance rapidly. In one of Weyand’s past studies, the slowest sprinters spent 0.135 sec on stance while the fastest spent about 0.09 sec on stance.

    Shorter time on stance is associated with stronger push against the ground, the decrease in time on stance is a stronger predictor of peak speed than the magnitude of the push.
  4. In addition, another study demonstrated that the best predictor of running speed was the ability of the athlete to apply more force to the ground during stance phase, not the length of time fhe foot was on the ground.
  5. Admin2

    Admin2 Administrator Staff Member

  6. wdd

    wdd Well-Known Member

  7. SeasonsChange

    SeasonsChange Member

    Which study was that?
  8. Weyand PG, Sternlight DB et al: Faster top running speeds are achieved with greater ground forces not more rapid leg movements. J Appl Physiol, 89:1991-1999, 2000.
  9. wdd

    wdd Well-Known Member

    I don't think that the above necessarily contradicts the article? The above research seems to be related to a broad range of sprinting abilities and suggests that the stance phase period tends to a minimum, which is where the article in the 'Economist' comes in. The article was talking about top sprinters and was suggesting that that during the contact phase there was insufficient time to allow maximal muscle contraction. The implication being that, in this group, generation of greater ground force could only occur if the foot remained on the ground longer or if the muscles could be induced to contract more rapidly/efficiently? The other possibility, I added, was that of an innovative change of running style, ie the equivalent of what the Fosbury flop did to the long jump? The first idea that comes to mind is a hundred metres sprint where rather than run over the finishing line the sprinter long jumps the final few metres? The second idea that comes to mind is training sprinters to massively overstride or to bound all or some of the race.

    For me, it raises some interesting questions. When a top sprinter long jumps, for example 8m, is the final pre-jump contact period longer than the previous step contact period? How does the ground force generated compare on each of these contact periods? Following on from that, how fast does he cover the 8 m jump?

    For any runner, as they increase velocity, does the ground force vector increase proportionately, ie do the horizontal and vertical components increase proportionately or does the angle of the vector change with respect to the ground?

  10. David Smith

    David Smith Well-Known Member

    Basic physics says this is true (kind of) since the longer a constant force is applied the greater the terminal velocity for a constant mass.

    So it only requires a constant acceleration of 1.83m/s^2 to achieve displacement of 100meters in 10 seconds. For an 80kg (frictionless) mass this would only require a constant force applied of 146.4 Newtons. The peak force applied to the ground by the foot during sprinting is more like 2000N (mainly in the wrong direction :eek:) which equates to accelerations of 25m/s^2, however this is minus gravity at 10m/s^2 and friction and only applied for a few milliseconds so the actual velocity is relatively low. If a 80kg sprinter, with a stride cadence of 2 Hz, could apply 2000N for 1 second each step in the direction of progression without any resisting friction or gravity then he'd soon be several miles away. In fact in 10 seconds he would go 1375metres, but then without gravity and friction he could'nt actually go anywhere.

    Blimey I hope my maths are right :eek:

    Regards Dave
  11. Sicknote

    Sicknote Active Member

    "Forcing the Issue": http://speed-development.com/Rice-Speed-SymposiumTalk-pdf-version-for-Casey.pdf

    Peter Weyand fails to understand that only 2 muscles are active during the push-off phase.

    It's the tendons that provide the real pop, not active contractions of the muscles. Jonathan Edwards was a genius that knew this. He covered the ground at 11.9m/s during his WR jump of 18.29m in Gothenburg (faster (m/s) than Carl Lewis running his personal best of 9.86secs over 100m).

    It's the same with animals. Very little muscularity.
  12. wdd

    wdd Well-Known Member

    It's the tendons that provide the real pop, not active contractions of the muscles. Jonathan Edwards was a genius that knew this. He covered the ground at 11.9m/s during his WR jump of 18.29m in Gothenburg (faster (m/s) than Carl Lewis running his personal best of 9.86secs over 100m).

    It's the same with animals. Very little muscularity.[/QUOTE]

    But is it not the contraction of muscles that is ultimately responsible for the energy stored in the tendons, ie no matter how good the tendons are at storing and restuting the stored energy it is muscular contraction that is responsible for putting the energy there in the first place?

    Was Jonathan Edwards a genius because of his athletic performance? Does genius in one area transfer to other areas, ie he was a great athlete therefore he is a great scientist?

  13. wdd

    wdd Well-Known Member

    Right or wrong, I like your maths.

    If we can just turn your conclusions into a placebo it will be worth at least a second, possibly a minute, off the world 100m record probably including, new and simultaneous long jump, high jump and poless vault records. In fact it might even be possible for man to launch himself into orbit.

    More power to your elbow.

    Best wishes,

  14. Sicknote

    Sicknote Active Member

  15. Sicknote:

    First of all, if you provided us your real name, then myself, and many others here on Podiatry Arena, would be more inclined to respond to your postings.

    Please give us references for your following claims:

    1. Only 2 muscles are active during the push-off phase.

    2. It's the tendons that provide the real pop, not active contractions of the muscles.

    3. How an athlete becomes a "genius" by running faster.

    4. That animals do not need "muscularity" in order to run faster.

    It will be interesting to see if you have some research to back up your claims. I doubt you will find any.

    Making claims that are later proved to be false will do nothing to improve the strength of any of your subsequent claims in future posts here on Podiatry Arena. This is something you may want to strongly consider in future postings here.
  16. wdd

    wdd Well-Known Member

    Dear Sicknote,

    When these boys (Simon and Kevin) get you in their sights the chances are you will never stand again, corrected or otherwise, unless you have some sort of survival tactic. I recommend the 'Yes but no but' approach which could win the day for you and would at least confuse the opposition long enough to give you some thinking time.


    Now come on, get up, stop grovelling and remember that being wrong is not a good enough reason for not insisting that you are right. Kick, scratch, punch low, gouge, headbut and if they fight back run.

  17. Doubtful. I was trying to be nice.

    P.S. don't feed the trolls, Bill.
  18. I like the butterfly diagrams for the individual muscles. Nice visual.

    I'd like to have a play with their simulation and model which they link to in the paper. Unfortunately the software required doesn't seem to be available for a mac OS. Dave Smith, you might be able to do something clever with that model- like changing the leg stiffness on one side and see what this does to the COM pathway? Maybe model some flat-lined COM paths?
  19. David Smith

    David Smith Well-Known Member

    Oh Thanks! Can't I have an easy job like sweep the floor and make tea and some colouring in with crayons?:wacko:

  20. You love it. Numbers and stuff, oooooh. :drinks
  21. Sicknote:

    Your silence is deafening since you don't seem to be able to back up your statements with references from any source. Maybe next time, before you throw around claims so confidently on this forum for medical professionals, you make sure that your claims are backed up by more than just your personal opinion.
  22. And maybe, that you are a medical professional?
  23. Simon:

    Just spoke to Cary...he said you were his first interview this AM...busy boy you are!:drinks
  24. Yeah, not a huge fan of doing telephone interviews as I tend to ramble when I'm talking to a telephone for 40 minutes and then I think of what I should have said after the event. I much prefer to write the answers to questions myself, gives me more time to reflect and construct the answer. This one is obviously scheduled for publication soon: http://www.ncbi.nlm.nih.gov/pubmed/22965220
  25. wdd

    wdd Well-Known Member

    A long time ago the high jump meant the straddle technique and then along came Dick Fosbury and the high jump was re-invented.

    Undoubtedly something similar happened with walking to explain the difference between ordinary fast walking and race walking.

    In each of the above cases an innovative and dramatic change in technique transformed the event.

    With running, until now, it's just seems more of the same, ie there has been no dramatic change in running technique. Is this because current running technique can not be bettered or because no one has attempted to imagine or develop a new style?

    I thought that Podiatry Arena might be able to start to answer the question but so far it's been the modern day, scientific, equivalent of swopping playing cards, ie research papers.

    Is sprinting awaiting a technical innovation similar to the Fosbury flop or is the current technique the best there is?

    Best wishes,

  26. David Smith

    David Smith Well-Known Member

    Run like an exaggerated version of Groucho Marks' walk. As kid's we loved to watch old Marks Brothers films and we would have races or chases running like this, actually its more of a fast walk but it is a very fast walk and it can become a run. The thing is the legs are more compliant so the feet stay on the ground for longer relative to the flight stage. I've never formally studied the GRF integrals for this type of gait but I would imagine that the force time curve has a longer frequency but a lower amplitude. This flexible leg style allows longer concentric muscle contraction thru the stance phase but reduces the elastic energy storage potential of the stiffer tissues i.e tendons.

    Maybe this is the kind of thing you were thinking of?

    Regards Dave
  27. Groucho running has been studied. At the risk of boring bill with another paper, I'll find the references later when I have more time.
  28. Sicknote

    Sicknote Active Member

  29. The thing with Groucho running is that it lowers reaction forces, increases duration of contact and costs (a lot) more energy.

    If we think in terms of impulse, there may be no net gain since despite the increased duration of contact, the reaction forces are lower: impulse = force x time, so low force for longer time might not give any advantage over large force for shorter time.

    Increased energy cost means that Groucho is probably not good for breaking distance running records, but in short course sprinting the energy cost really doesn't matter too much.

    So who might Groucho suit? Well, if we look to the animal kingdom, elephants use this style of running gait... Thus, for the fatties taking up running to try to loose weight, it might be the way forward... Lower reaction forces + increased energy cost = weight loss, however, I'd watch out for patella tendonitis/ cardiac arrest.
  30. BTW, when I wrote: / I literally did mean stroke.;)

    Here's weird: on numerous occasions I've driven past over-weight runners and shouted out of the car window something along the lines of "I'd pack it in if I where you, love". To which my passenger has said something like: "what do you mean?" And I've said: "they're not even running, they haven't got a "float phase"". Actually in hindsight they were Groucho running. In other words their self selected running style was attempting to reduce GRF by increasing the contact time... what a wonderful thing the unconscious mind is. And how embarrassed am I?

    From now on I'll shout: "get on, fatty Groucho. Do you want a cigar?" which I think will be far more acceptable. Don't you?
  31. Simon:

    Even the trolls like you....how do you do it?! Maybe even Blaise likes you too?
  32. Skill, maturity, judgement... doubtful.
  33. For all of you who are interested in foot orthosis therapy, Dr. Spooner's comments in this soon-to-be-published roundtable discussion are some of the finest comments ever written on this subject. In fact, I consider this article to be Dr. Spooner's best thoughts ever on foot orthosis therapy. It is both a state-of-the-art and excellent commentary on the subject. I think you will all enjoy it.:drinks
  34. Dr. Steven King

    Dr. Steven King Well-Known Member

    Aloha Bill,

    We believe that the technical innovation has arrived with the invention of the Spring Orthotic Device. By using advanced composites with a lever-spring system we can achieve greater GRF's and impulse with gait.

    This system is currently being tested for the US Department of Defense and the US Army's Medical Research and Material Command under the grant SBIR A11-109 "Advanced Composite Insoles for the Reduction of Stress Fractures."

    I will humbly admit that i have failed badly triing to help our fellow Podiatry Arena members and the head teachers and researchers of biomechanics at our podiatry colleges to under the basic physics and biomechanics of the technology.

    A Hui Hou,

    Kingetics- Enlightening Your Loads...TM
  35. wdd

    wdd Well-Known Member

    Sorry. I should have said an innovation in running technique as technical innovations, like the backbound jet rocket, could put the one stride or even one step four minute marathon within striking distance.

    A little aside. A question. Are the 50m, 100m, 200m, etc races (under whatever athletic association rules) running races or horizontal displacement races? In other words must the distance be covered using a technique falling within the definition of running or is it freestyle, ie could the distance be covered by cartwheeling for example and still be within the rules?

    In a walking race participants who runs are disqualified. In a running race is someone who walks disqualified or someone who falls, rolls over, gets up and starts running again? My own experience is that they are not disqualified. Does that mean that running races are mixed technique races, eg walking falling over and rolling are included within the definition of running?

    If that is the case then Groucho walk/run, bounds, long jump, cartwheels, backflips, etc could be included.

    Even if the techniques suggested above are slower than running they would add to the spectacle. I for one, OK 0.95, would love to see the Olympic 100m horizontal displacement race including say, ten Groucho steps, five backflips, ten bounds, three forward rolls and finishing with a long jump. Yes?


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