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A Nov. 11 article in Scientific American cites the expert analysis of SMU physiologist and biomechanist Peter Weyand as part of an effort to explore the physics of speed and acceleration.
In a special partnership with NBC Learn, the science magazine set up an imaginary 40-yard dash to present additional information for the video series, “The Science of NFL Football.”
Weyand was posed the question: Imagine a 40-yard dash that races a wide receiver, a safety, an ostrich, an elephant and a pig — who would win?
See the excerpt below for Weyand’s answer.
Read the full story and see the video.
Weyand is an SMU associate professor of applied physiology and biomechanics in the Annette Caldwell Simmons School of Education & Human Development. He lead a team of experts in biomechanics and physiology that conducted experiments on Oscar Pistorius, a South African bilateral amputee track athlete. Pistorius has made headlines trying to qualify for races against runners with intact limbs, including the Olympics.
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Excerpt:
Scientific American
If you want to be a professional football player, you’d better start practicing your 40-yard dash. It’s the gold standard for assessing a player’s speed and ability to accelerate, as NBC Learn’s segment on kinematics, motion, speed and acceleration shows.Human beings need about 10 yards to reach maximum velocity, so the 40 is really a test of both acceleration and speed — unlike a longer sprint, such as the 100, which is more about a runner’s ability to maintain maximum speed. Acceleration depends on how much force runners can put into the ground (and thus receive back) relative to their mass. For this reason, the smaller you are the easier it is to accelerate rapidly. That’s why gymnasts, for example, are generally small — they must be able to generate a large amount of force relative to mass to accelerate enough to run and perform multiple flips in a row. Imagine an offensive lineman trying to do that! Wide receivers, running backs and defensive backs are not as massive as linemen, and therefore are very good accelerators, which is one reason they can handily outrun the latter in a 40-yard dash.
At present, no standard method or variable exists to quantify a human or animal’s top acceleration. One reason: the variable changes with every step until top speed is reached, making a tangible value a moving target. As a result, comparing the top accelerations of humans and other animals is difficult. Nevertheless, it’s true that smaller animals are better at accelerating — think of how quickly a squirrel can dart up a tree trunk, for example.
Speaking of squirrels, imagine a 40-yard dash that races a wide receiver, a safety, an ostrich, an elephant and a pig — who would win? “The ostrich wins pretty easily,” says Peter Weyand, a professor of applied physiology and biomechanics at Southern Methodist University. “And then would probably come the wide receiver, the safety, squirrel, the pig and, finally, the elephant.”
The ostrich, although bigger than a human, is built for speed. “The easiest way to explain why the ostrich is fast is that it has long legs,” Weyand says. It also runs on its toes, and what looks like a backward knee is actually its ankle. Most of the bird’s leg muscles reside on short thighbones, so the task of accelerating and maintaining speed is left to long, light limbs.
Read the full story and see the video.
Weyand is an expert in the locomotion of humans and other terrestrial animals with broad research interests that focus on the relationships between muscle function, metabolic energy expenditure, whole body mechanics and performance.
An expert in the scientific basis of gait and movement, his global interests in muscles and movement have made energy and performance central themes throughout his research career. Weyand’s research and expertise on the limits of human and animal performance have led to featured appearances on CNN, NHK Television in Japan, the Canadian Broadcasting Corporation, the History Channel, City TV of Toronto, CBS Boston and others.
Book a live interview
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To book a live or taped interview with Peter Weyand in the SMU News Broadcast Studio call SMU News at 214-768-7650 or email news@smu.edu. |
An article looking at the abilities of humans and animals to run long distances tapped into the research of SMU physiologist and biomechanist Peter Weyand.
Journalist Brian Resnick in Popular Mechanics cites Weyand’s knowledge to explain the differences at work between humans and animals in “The Animal Kingdom’s Top Marathoners.”
Weyand is an SMU associate professor of applied physiology and biomechanics in the Annette Caldwell Simmons School of Education & Human Development. His experience includes leading a team of experts in biomechanics and physiology that conducted experiments on Oscar Pistorius, a South African bilateral amputee track athlete. Pistorius has made world headlines trying to qualify for races against runners with intact limbs, including the Olympics.
Weyand is an expert in the locomotion of humans and other terrestrial animals with broad research interests that focus on the relationships between muscle function, metabolic energy expenditure, whole body mechanics and performance.
Related links
- Peter Weyand
- Journal of Applied Physiology: “The biological limits to running speed are imposed from the ground up”
- Annette Caldwell Simmons School of Education & Human Development
More SMU Research news
An expert in the scientific basis of gait and movement, his global interests in muscles and movement have made energy and performance central themes throughout his research career. Weyand’s research and expertise on the limits of human and animal performance have led to featured appearances on CNN, NHK Television in Japan, the Canadian Broadcasting Corporation, the History Channel, City TV of Toronto, CBS Boston and others.
Excerpt:
By Brian Resnick
Popular Mechanics
Compared to other land mammals, humans are remarkably good at running long distances. Our upright posture and ability to shed heat — through sweating — are what allow people to run more than 20 miles during a race. Very few other animals can sustain such distances, especially at the speeds that top human athletes perform. But there is plenty of competition out there — nature is full of species adapted for running distance. Here’s a look at six of the best marathoners in the animal kingdom, from slowest to fastest.Through years of selective breeding, racehorses have gained a built-in biological mechanism for efficient blood — the kind that certain human athletes can only achieve by doping.
“When they start to exercise, their spleen will kick out a whole bunch of red bloods cells into their system, into their cardiovascular system to make the oxygen carrying capacity of their blood go up,” says Peter Weyand, professor of physiology and biomechanics at Southern Methodist University. Human blood dopers transfuse blood before a race to achieve an increased aerobic capacity. However, the horse naturally release blood cells moments after starting to a gallop.
For the last 30 years, the Welsh town of Llanwrtyd Wells has hoted a 22-mile, man-versus-horse race. Humans have only won the race twice, but top runners usually only finish 10 minutes after the animals. Where horses exceed in oxygen efficiency, humans make up for in temperature regulation. In the beginning of the race the horses tend to have a 30 minute lead, but toward the end, that advantaged is cut to a couple of minutes. Over the course of the race, humans are more efficient at expelling heat — not to mention they aren’t running with a rider on their back. On a hot day, humans can win much more easily.
Are humans born to run? Some experts think that humans have, indeed, evolved to be distance runners — the better to track prey, evade predators and migrate. While there is some debate on running and human evolution, there is no question that we are up there in the animal kingdom for speeds at marathon distances. There is no one reason, but the efficiency of our cooling systems — our ability to sweat — and having an upright posture, to minimize our sun exposure and maximize our lung capacity, are some of the primary reasons we are skilled distance runners.
One major difference between humans and animals is that we don’t have in-born endurance; we have to train.
Peter Weyand says that compared to other animals, humans have a high energy cost of running — we spend more energy in each stride relative to our size. But unlike wild animals, we can motivate ourselves to run, and through training we can increase our aerobic scope — the amount of aerobic activity one can achieve. “Even though
[humans] are good at regulating heat, they have more heat to dump because their economy is poor,” he says. Strict training regimens and the ability to sweat can make up for that lack.
Read the full story.
Book a live interview
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To book a live or taped interview with Peter Weyand in the SMU News Broadcast Studio call SMU News at 214-768-7650 or email news@smu.edu. |
Related links
- Peter Weyand
- Journal of Applied Physiology: “The biological limits to running speed are imposed from the ground up”
- Annette Caldwell Simmons School of Education & Human Development
More SMU Research news
Jamaican sprinter Usain Bolt‘s record-setting performances have unleashed a wave of interest in the ultimate limits to human running speed. A new study published Jan. 21 in the Journal of Applied Physiology offers intriguing insights into the biology and perhaps even the future of human running speed.
The newly published evidence identifies the critical variable imposing the biological limit to running speed, and offers an enticing view of how the biological limits might be pushed back beyond the nearly 28 miles per hour speeds achieved by Bolt to speeds of perhaps 35 or even 40 miles per hour.
The new paper, “The biological limits to running speed are imposed from the ground up,” was authored by Peter Weyand of Southern Methodist University; Rosalind Sandell and Danille Prime, both formerly of Rice University; and Matthew Bundle of the University of Wyoming.
“The prevailing view that speed is limited by the force with which the limbs can strike the running surface is an eminently reasonable one,” said Weyand, associate professor of applied physiology and biomechanics at SMU in Dallas.
“If one considers that elite sprinters can apply peak forces of 800 to 1,000 pounds with a single limb during each sprinting step, it’s easy to believe that runners are probably operating at or near the force limits of their muscles and limbs,” he said. “However, our new data clearly show that this is not the case. Despite how large the running forces can be, we found that the limbs are capable of applying much greater ground forces than those present during top-speed forward running.”
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| SMU sprinter Ebony Cuington. Photo: SMU Athletics |
In contrast to a force limit, what the researchers found was that the critical biological limit is imposed by time — specifically, the very brief periods of time available to apply force to the ground while sprinting.
In elite sprinters, foot-ground contact times are less than one-tenth of one second, and peak ground forces occur within less than one-twentieth of one second of the first instant of foot-ground contact.
The researchers took advantage of several experimental tools to arrive at the new conclusions. They used a high-speed treadmill capable of attaining speeds greater than 40 miles per hour and of acquiring precise measurements of the forces applied to the surface with each footfall. They also had subjects’ perform at high speeds in different gaits. In addition to completing traditional top-speed forward running tests, subjects hopped on one leg and ran backward to their fastest possible speeds on the treadmill.
The unconventional tests were strategically selected to test the prevailing beliefs about mechanical factors that limit human running speeds — specifically, the idea that the speed limit is imposed by how forcefully a runner’s limbs can strike the ground.
However, the researchers found that the ground forces applied while hopping on one leg at top speed exceeded those applied during top-speed forward running by 30 percent or more, and that the forces generated by the active muscles within the limb were roughly 1.5 to 2 times greater in the one-legged hopping gait.
The time limit conclusion was supported by the agreement of the minimum foot-ground contact times observed during top-speed backward and forward running. Although top backward vs. forward speeds were substantially slower, as expected, the minimum periods of foot-ground contact at top backward and forward speeds were essentially identical.
According to Matthew Bundle, an assistant professor of biomechanics at the University of Wyoming, “The very close agreement in the briefest periods of foot-ground contact at top speed in these two very different gaits points to a biological limit on how quickly the active muscle fibers can generate the forces necessary to get the runner back up off the ground during each step.”
The researchers said the new work shows that running speed limits are set by the contractile speed limits of the muscle fibers themselves, with fiber contractile speeds setting the limit on how quickly the runner’s limb can apply force to the running surface.
The established relationship between ground forces and speed allowed the researchers to calculate how much additional speed the hopping forces would provide if they were utilized during running.
“Our simple projections indicate that muscle contractile speeds that would allow for maximal or near-maximal forces would permit running speeds of 35 to 40 miles per hour and conceivably faster,” Bundle said.
The artificial lower limbs of double-amputee Olympic hopeful Oscar Pistorius give him a clear and major advantage over his competition, taking 10 seconds or more off what his 400-meter race time would be if his prosthesis behaved like intact limbs.
That’s the conclusion — released to the public for the first time — of human performance experts Peter Weyand of Southern Methodist University and Matthew Bundle of the University of Wyoming.
The Weyand-Bundle conclusion is part of a written Point-Counterpoint style debate published Nov. 19 online in the “Journal of Applied Physiology.” Weyand and Bundle were the first two authors of the study publishing the test results acquired as part of the legal appeal process undertaken after the governing body of Track and Field — the International Association of Athletics Federations (IAAF) — banned Pistorius from able-bodied track competitions, including the Olympics.
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| SMU’s Peter Weyand and Oscar Pistorius during testing. Marquee photo and inside photos: By Jeff Fitlow/Rice University |
In banning Pistorius, the IAAF had concluded on the basis of other data that Pistorius’ J-shaped, artificial lower limbs, called “Cheetahs” by the manufacturer, gave him a competitive advantage over able-bodied competitors. But the ban subsequently was overturned on appeal to the Court of Arbitration for Sport (CAS) in Lausanne, Switzerland.
The case has been considered groundbreaking for the eligibility of disabled athletes and the regulation of prosthetic technology in sport. Pistorius hopes to qualify for the 2012 Olympics.
The newly released conclusion from Weyand and Bundle analyzes the scientific evidence and quantifies the competitive advantage provided by Pistorius’ “Cheetah” limbs.
Weyand says: “Pistorius’ sprinting mechanics are anomalous, advantageous and directly attributable to how much lighter and springier his artificial limbs are. The blades enhance sprint running speeds by 15-30 percent.”
Below the knee, Pistorius’ limbs weigh less than half as much as the limbs of an able-bodied male sprinter.
Bundle notes that most of the 15-30 percent speed advantage enjoyed by Pistorius is explained by how quickly the lightweight blades allow him to reposition his limbs: “Even in comparison to those male sprinters with the most extreme adaptations for speed in recorded human history, Oscar Pistorius has limb repositioning times that are literally off the charts. Usain Bolt is considered somewhat freakish because he outruns his opponents by 2-4 percent. At top speed, Oscar Pistorius repositions his limbs 15 percent more rapidly than six of the most recent world record holders in the 100 meter dash, including Usain Bolt.”
Pistorius’ case was successfully presented by the law firm Dewey & LeBoeuf of New York.
“We are pleased to finally be able to go public with conclusions that the publishing process has required us to keep confidential until now. We recognized that the blades provide a major advantage as soon as we analyzed the critical data more than a year and a half ago,” said Weyand and Bundle in a statement.
Speaking for both investigators, Weyand said: “We admire the unique athletic achievements of Oscar Pistorius and are grateful for his willingness to share these important results for the general benefit of athletes and athletics.”
A different interpretation of the Pistorius data appeared as part of the written Point-Counterpoint style debate in the “Journal of Applied Physiology.”
Weyand and Bundle based their conclusions on data indicating:
Pistorius’ lightweight blades allow him to reposition his limbs 15.7 percent more rapidly than five of the most recent former world-record holders in the 100-meter dash.
The springy, lightweight blades allow Pistorius to attain the same sprinting speeds while applying 20 percent less ground force than intact-limb runners.
The springy blades reduce the muscle forces Pistorius requires for sprinting to less than half of intact-limb levels.
Peter Weyand is an associate professor of applied physiology and biomechanics in SMU’s Annette Caldwell Simmons School of Education & Human Development.
Matthew Bundle is an assistant professor of biomechanics in the College of Health Sciences at the University of Wyoming.
Read news coverage of this story.
Related links:
JAP: Point-Counterpoint “Artificial limbs do/do not make artificial running speeds possible” target=blank
JAP Study: The fastest runner on artificial legs: Different limbs, similar function?
Science Daily: Oscar Pistorius, amputee sprinter runs differently
New York Times: An amputee advantage?
Times: Oscar Pistorius to make run at London 2012
Study revives Olympic prospects for amputee sprinter
T.O. Sports: Blade runner beats the ban and his ‘Cheetahs’ are no longer ‘cheating’
AFP: ‘Bladerunner’ Pistorius wins appeal against Olympic ban
IAAF: Pistorius is eligible for IAAF competition
New York Times: Amputee ineligible for Olympic events
TIME Magazine: How Fast Can Humans Go?
The Christian Science Monitor asked human locomotion expert Peter Weyand to weigh in on the subject of how fast human beings might ultimately be able to run. Weyand’s analysis was published as an opinion essay in the newspaper’s Sept. 4 online version.
Earlier Weyand was interviewed by the online magazine Matador Sports for the piece “Calculating the Human Speed Limit,” which published Aug. 21, 2009; and by Britain’s Daily Express, which published “How Fast Can a Bolt of Lightning Travel?” in its July 26, 2009 edition. Weyand was also quoted by the blog SBS.com.au in a story July 22, 2009.
Weyand, a physiologist and biomechanist, is an SMU associate professor of applied physiology and biomechanics in the Annette Caldwell Simmons School of Education & Human Development. He recently lead a team of experts in biomechanics and physiology that conducted experiments on Oscar Pistorius. The South African bilateral amputee track athlete, Pistorius has made world headlines trying to qualify for races against runners with intact limbs, including the Olympics.
Excerpt:
By Peter Weyand
For The Christian Science Monitor
DALLAS — How fast might human beings ultimately run?Usain Bolt’s recent assault on the track and field record book — running 9.58 in the 100m and reaching a top speed of nearly 28 mph — has raised this question at a crucial crossroads for organized athletics. While specific predictions by modern science are not precise, the general influence of scientific advancement is poised to overwhelm human performance and organized athletics as we have known them.
Although we can readily quantify the forces acting on the body and predict the motion they produce using classical Newtonian mechanics, we still have an incomplete understanding of the process of force production within the body, and how the body’s internal forces eventually translate into motion.
Conceivably, the secret to blazing running speeds might be explained by either of two abilities: repositioning the limbs quickly through the air, or hitting the ground forcefully with each step. Contrary to intuition, fast runners achieve their greater speeds, not by repositioning their legs any more rapidly, but rather by hitting the ground with greater force and quickness than slower runners do.
How hard and how quickly do elite sprinters hit the ground? Once up to speed, an athlete like Usain Bolt will hit the ground with a force equivalent to roughly 1,000 pounds, and do so within five 100ths of a second of the first instant of foot-ground contact.
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Peter Weyand
Annette Caldwell Simmons School of Education & Human Development