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.
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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?
Bill
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I wouldn't trust an article on running biomechanics that was published in "The Economist". -
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. -
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.
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Built for speed: musculoskeletal structure and sprinting ability
Other threads tagged with sprinting -
I am attaching the address for the above article. The reference to the application of force to the ground is in the last paragraph.
http://www.economist.com/node/21559903
Bill -
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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?
Bill -
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 -
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. -
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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?
Bill -
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,
Bill -
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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. -
http://www.youtube.com/watch?v=aX9InPSPM6U
The muscle is most "active" when red; "quietest" when blue. -
As far as I ken, genius is a measure of mental ability, not physical capability. (I wish I could be deep as well as just macho- right?).
This paper seems to be cited quite frequently in regard to muscle activation during running:
http://www.me.utexas.edu/~neptune/Papers/job39(11).pdf -
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.
http://www.youtube.com/watch?v=zExc6SK4kpA
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.
Bill -
P.S. don't feed the trolls, Bill. -
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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? -
Dave -
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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. -
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Just spoke to Cary...he said you were his first interview this AM...busy boy you are!:drinks -
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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,
Bill -
Maybe this is the kind of thing you were thinking of?
Regards Dave -
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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. -
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? -
Even the trolls like you....how do you do it?! Maybe even Blaise likes you too? -
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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,
Steve
Kingetics- Enlightening Your Loads...TM -
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?
Bill
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