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Daily Mail: Researchers reveal the mechanics of running is simpler than thought – and it could revolutionise shoe design

New study: Pattern of force on the ground is due to the motion of two parts of the body

Reporter Stacy Liberatore with London’s Daily Mail newspaper covered the research of Peter Weyand and the SMU Locomotor Laboratory. Weyand, who is Glenn Simmons Professor of Applied Physiology and professor of biomechanics in the Department of Applied Physiology and Wellness in SMU’s Annette Caldwell Simmons School of Education and Human Development, is the director of the Locomotor Lab.

Other authors on the study were Laurence Ryan, a physicist and research engineer in the lab, and
Kenneth Clark , previously with the lab and now an assistant professor in the Department of Kinesiology at West Chester University in West Chester, Penn.

The three have developed a concise approach to understanding the mechanics of human running. The research has immediate application for running performance, injury prevention, rehab and the individualized design of running shoes, orthotics and prostheses. The work integrates classic physics and human anatomy to link the motion of individual runners to their patterns of force application on the ground — during jogging, sprinting and at all speeds in between.

The Daily Mail article, “Researchers reveal the mechanics of running is simpler than thought – and it could revolutionise shoe design,” published Jan. 31, 2017.

Read the full story.

EXCERPT:

By Stacy Liberatore
Daily Mail

A study has found a new explanation for the basic mechanics of human running.

While observing Olympic-caliber sprinters, researchers discovered that a runner’s pattern of force application on the ground is due to the motion of just two parts of the body: the contacting leg and the rest of the body.

The new approach could help create new patterns to optimize the design of running shoes, orthoses and prosthetics, as experts are able to see exactly how a person runs.

The Southern Methodist University (SMU) researchers explained that the basic concept of their ‘two-mass model’ is relatively simple — a runner’s pattern of force application on the ground is due to the motion of two parts of the body: the lower portion of the leg that is contacting the ground, and the sum total of the rest of the body.

The force contributions of the two body parts are each predicted from their largely independent motions when they have foot-ground contact.

And then combined to predict the overall pattern.

The final prediction relies only upon classical physics and a characteristic link between the force and motion for the two body parts.

‘Our model inputs are limited to contact time on the ground, time in the air, and the motion of the ankle or lower limb.

‘From three basic stride variables we are able to predict the full pattern of ground-force application,’ said Laurence Ryan, who is a physicist and research engineer at SMU’s Locomotor Performance Laboratory.

‘The approach opens up inexpensive ways to predict the ground reaction forces and tissue loading rates.’

Read the full story.

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New study connects running motion to ground force, provides patterns for any runner

New approach simplifies the physics of running, enabling scientists to predict ground force patterns; applies to rehab, shoe design and athletic performance.

Researchers at Southern Methodist University, Dallas, have developed a concise approach to understanding the mechanics of human running. The research has immediate application for running performance, injury prevention, rehab and the individualized design of running shoes, orthotics and prostheses. The work integrates classic physics and human anatomy to link the motion of individual runners to their patterns of force application on the ground – during jogging, sprinting and at all speeds in between.

Researchers at Southern Methodist University in Dallas have developed a concise new explanation for the basic mechanics involved in human running.

The approach offers direct insight into the determinants of running performance and injuries, and could enable the use of individualized gait patterns to optimize the design of shoes, orthoses and prostheses according to biomechanics experts Kenneth Clark , Laurence Ryan and Peter Weyand, who authored the new study.

The ground force-time patterns determine the body’s motion coming out of each step and therefore directly determine running performance. The impact portion of the pattern is also believed to be a critical factor for running injuries.

“The human body is mechanically complex, but our new study indicates that the pattern of force on the ground can be accurately understood from the motion of just two body parts,” said Clark, first author on the study and currently an assistant professor in the Department of Kinesiology at West Chester University in West Chester, Pennsylvania.

“The foot and the lower leg stop abruptly upon impact, and the rest of the body above the knee moves in a characteristic way,” Clark said. “This new simplified approach makes it possible to predict the entire pattern of force on the ground — from impact to toe-off — with very basic motion data.”

This new “two-mass model” from the SMU investigators substantially reduces the complexity of existing scientific explanations of the physics of running.

Existing explanations have generally relied upon relatively elaborate “multi-mass spring models” to explain the physics of running, but this approach is known to have significant limitations. These complex models were developed to evaluate rear-foot impacts at jogging speeds and only predict the early portion of the force pattern. In addition, they are less clearly linked to the human body itself. They typically divide the body into four or more masses and include numerous other variables that are hard to link to the actual parts of a human body.

The SMU model offers new insight by providing concise, accurate predictions of the ground force vs. time patterns throughout each instant of the contact period. It does so regardless of limb mechanics, foot-strike type and running speed.

“Our model inputs are limited to contact time on the ground, time in the air, and the motion of the ankle or lower limb. From three basic stride variables we are able to predict the full pattern of ground-force application,” said Ryan, who is a physicist and research engineer at SMU’s Locomotor Performance Laboratory.

“The approach opens up inexpensive ways to predict the ground reaction forces and tissue loading rates. Runners and other athletes can know the answer to the critical functional question of how they are contacting and applying force to the ground.” added Ryan.

Current methods for assessing patterns of ground force application require expensive in-ground force platforms or force treadmills. Additionally, the links between the motions of an athlete’s body parts and ground forces have previously been difficult to reduce to basic and accurate explanations.

The researchers describe their new two-mass model of the physics of running in the article, “A general relationship links gait mechanics and running ground reaction forces,” published in the Journal of Experimental Biology.

“From both a running performance and injury risk standpoint, many investigations over the last 15 years have focused on the link between limb motion and force application,” said Weyand, who is the director of SMU’s Locomotor Performance Laboratory. “We’re excited that this research can shed light on this basic relationship.”

Overall force-time pattern is the sum of two parts
Traditional scientific explanations of foot-ground forces have utilized different types of spring and mass models ranging from complex to very simple. However, the existing models have not been able to fully account for all of the variation present in the force-time patterns of different runners — particularly at speeds faster than jogging. Consequently, a comprehensive basis for assessing performance differences, injury risks and general running mechanics has not been previously available.

The SMU researchers explain that the basic concept of the new approach is relatively simple — a runner’s pattern of force application on the ground is due to the motion of two parts of the body: the lower portion of the leg that is contacting the ground, and the sum total of the rest of the body.

The force contributions of the two body parts are each predicted from their largely independent, respective motions during the foot-ground contact period. The two force contributions are then combined to predict the overall pattern. The final prediction relies only upon classical physics and a characteristic link between the force and motion for the two body parts.

New approach can be applied accurately and inexpensively
The application of the two-mass approach is direct and immediate.

“Scientists, clinicians and performance specialists can directly apply the new information using the predictive approach provided in the manuscript,” Clark said. “The new science is well-suited to assessing patterns of ground-force application by athletes on running tracks and in performance training centers.”

These capabilities have not been possible previously, much less in the inexpensive and accurate manner that the new approach allows for with existing technology.

“The only requirement is a quality high-speed camera or decent motion sensor and our force-motion algorithms,” Clark said. “It’s conceivable that even shoe stores would benefit by implementing basic treadmill assessments to guide footwear selection from customer’s gait mechanics using the approach.”

A critical breakthrough for the SMU researchers was recognition that the mass contribution of the lower leg did not vary for heel vs. forefoot strikes and was directly quantifiable. Their efforts lead them to recognize the initial force contribution results from the quick stopping of the lower part of the leg — the shin, ankle and foot — which all come down and stop together when the foot hits the ground.

Olympic sprinters were a clue to discovery
The SMU team discovered a general way to quantify the impact forces from the large impacts observed from Olympic-caliber sprinters. Like heel strikers, the patterns of Olympic sprinters exhibit a sharp rising edge peak that results from an abrupt deceleration of the foot and lower leg. However, sprinters accomplish this with forefoot impacts rather than the heel-first landing that most joggers use.

“The world-class sprinters gave us a big signal to figure out the critical determinants of the shape of the waveform,” said Weyand. “Without their big impact forces, we would probably have not been able to recognize that the ground-force patterns of all runners, regardless of their foot-strike mechanics and running speed, have two basic parts.”

When the researchers first began to analyze the seemingly complicated force waveform signals, they found that they were actually composed of two very simple overlapping waveforms, Ryan said.

“Our computer generated the best pattern predictions when the timing of the first waveform coincided with the high-speed video of the ankle stopping on impact. This was true to within a millisecond, every single time. And we did it hundreds of times,” he said. “So we knew we had a direct physical relationship between force and motion that provided a critical insight.”

New approach has potential to diagnose injury, rehab
The SMU team’s new concise waveforms potentially have diagnostic possibilities, Weyand said.

For example, a runner’s pre-injury waveforms could be compared to their post-injury and post-rehab waveforms.

“You could potentially identify the asymmetries of runners with tibial stress fractures, Achilles tendonitis or other injuries by comparing the force patterns of their injured and healthy legs,” he said.

And while medical images could suggest the injury has healed, their waveforms might tell a different story.

“The waveform patterns might show the athlete continues to run with less force on the injured limb. So it may offer an inexpensive diagnostic tool that was not previously available,” Weyand said.

Weyand is Glenn Simmons Professor of Applied Physiology and professor of biomechanics in the Department of Applied Physiology and Wellness in SMU’s Annette Caldwell Simmons School of Education and Human Development.

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ESPN: SMU Locomotor Performance Lab spotlighted during SMU-Texas A&M football game

Weyand’s research on the limits of human and animal performance has led to featured appearances on the BBC, the Canadian Broadcasting Corporation, CNN, the Discovery Channel, the History Channel, NHK Television Japan, NPR and others.

The SMU Locomotor Performance Laboratory saw a few minutes of play during the SMU-Texas A&M football game Saturday, Sept. 20, 2014.

ESPN’s broadcast team stopped by to see the reigning U.S. national 400-meter champion Gil Roberts on the lab’s high-tech treadmill.

SMU physiologist and biomechanics expert Peter Weyand and his team at the lab study human performance and the boundaries of human speed.

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Weyand, recognized worldwide as an expert in human running performance, worked with Roberts on the lab’s specially equipped treadmill — it can go up to 90 miles an hour — which can measure how forcefully an athlete’s feet hit the ground.

As an athlete runs, the lab’s ultra high-speed video system (normally used in the entertainment-animation-video game design industry) can capture 1,000 frames a second, delivering accurate and detailed data about a runner’s biomechanics.

In the lab’s most recent published study, “Key to speed? Elite sprinters are unlike other athletes — deliver forceful punch to ground,” the scientists found that the key to speed is how forcefully athletes hit the ground — not how quickly they reposition their legs. They found that at top speed the world’s fastest runners take just as long to reposition their legs as an average Joe.

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.

His research draws on the largely distinct traditions of human exercise physiology and comparative biomechanics to consider basic functional issues.

Weyand’s research on the limits of human and animal performance has led to featured appearances on the British Broadcasting Corporation, the Canadian Broadcasting Corporation, CNN, the Discovery Channel, the History Channel, NHK Television Japan, National Public Radio and others.

The lab is part of the Annette Caldwell Simmons School of Education & Human Development.

Follow SMUResearch.com on twitter at @smuresearch.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.

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Key to speed? Elite sprinters are unlike other athletes — deliver forceful punch to ground

New research finds that world-class sprinters attack the ground to maximize impact forces and speed

The world’s fastest sprinters have unique gait features that account for their ability to achieve fast speeds, according to two new studies from Southern Methodist University, Dallas.

The new findings indicate that the secret to elite sprinting speeds lies in the distinct limb dynamics sprinters use to elevate ground forces upon foot-ground impact.

“Our new studies show that these elite sprinters don’t use their legs to just bounce off the ground as most other runners do,” said human biomechanics expert and lead author on the studies Ken Clark, a researcher in the SMU Locomotor Performance Laboratory. “The top sprinters have developed a wind-up and delivery mechanism to augment impact forces. Other runners do not do so.”

The new findings address a major performance question that has remained unanswered for more than a decade.

Previous studies had established that faster runners attain faster speeds by hitting the ground more forcefully than other runners do in relation to their body weight. However, how faster runners are able to do this was fully unknown. That sparked considerable debate and uncertainty about the best strategies for athletes to enhance ground-force application and speed.

“Elite speed athletes have a running pattern that is distinct,” Clark said. “Our data indicate the fastest sprinters each have identified the same solution for maximizing speed, which strongly implies that when you put the physics and the biology together, there’s only one way to sprint really fast.”

The critical and distinctive gait features identified by the study’s authors occur as the lower limb approaches and impacts the ground, said study co-author and running mechanics expert Peter Weyand, director of the SMU Locomotor Performance Lab.

“We found that the fastest athletes all do the same thing to apply the greater forces needed to attain faster speeds,” Weyand said. “They cock the knee high before driving the foot into the ground, while maintaining a stiff ankle. These actions elevate ground forces by stopping the lower leg abruptly upon impact.”

The new research indicates that the fastest runners decelerate their foot and ankle in just over two-hundredths of a second after initial contact with the ground.

The researchers reported their findings with co-author and physicist Laurence J. Ryan, research engineer for the SMU Locomotor Performance Laboratory in the Annette Caldwell Simmons School of Education & Human Development.

The finding that elite sprinters apply greater ground forces with a distinctive impact pattern is reported in the Journal of Applied Physiology in the article, “Are running speeds maximized with simple-spring stance mechanics?” It appears online at http://bit.ly/1Be92Mk in advance of appearing in the print journal.

The finding that faster athletes deliver a firm, rapid punch to the ground upon contact is reported in The Journal of Experimental Biology, in the article “Foot speed, foot-strike and footwear: linking gait mechanics and running ground reaction forces.” It appears online at http://bit.ly/1uskM9v.

Studies compared data from competitive sprinters to other athletes
The tests conducted at SMU’s Locomotor Performance Lab compared competitive sprinters to other fast-running athletes.

The competitive sprinting group included track athletes who specialized in the 100- and 200-meter events. More than half had international experience and had participated in the Olympics and Track and Field World Championships.

They were compared to a group of athletes that included competitive soccer, lacrosse and football players.

All the athletes in both groups had mid- and fore-foot strike patterns. Their running mechanics were tested on a custom, high-speed force treadmill that allowed the researchers to capture and analyze hundreds of footfalls at precisely controlled speeds. Video captured for the studies is posted to the SMU Locomotor Performance Lab Youtube channel. Images on flickr are at http://bit.ly/YKwAtB.

The researchers measured ground-force patterns over a full range of running speeds for each athlete from a jog to top sprinting speed.

“We looked at running speeds ranging from 3 to 11 meters per second,” Clark said. “Earlier studies in the field of biomechanics have examined ground reaction force patterns, but focused primarily on jogging speeds between 3 and 5 meters per second. The differences we found became identifiable largely because of the broad range of speeds we examined and the caliber of the sprinters who participated in the study.”

Classic spring model of running does not explain the unique gait features of top sprinters
The contemporary view of running mechanics has been heavily influenced by the simple spring-mass model, a theory first formulated in the late 1980s. The spring-mass model assumes the legs work essentially like the compression spring of a pogo stick when in contact with the ground.

In this theory, during running at a constant speed on level ground, the body falls down out of the air. Upon landing, the support leg acts like a pogo stick to catch the body and pop it back up in the air for the next step.

It’s been generally assumed that this classic spring model applies to faster running speeds and faster athletes as well as to slower ones.

Elite sprinters do not conform to widely accepted theories of running mechanics
Clark, Ryan and Weyand questioned whether such a passive catch-and-rebound explanation could account for the greater ground forces widely understood as the reason why sprinters achieve faster speeds.

After the researchers gathered ground reaction force waveform data, they found that sprinters differed from other athletes. From there they compared the waveforms to those predicted by the simple spring in the classic model.

“The elite sprinters did not conform to the spring-model predictions,” said Clark. “They deviated a lot, specifically during the first half of the ground-contact phase. Our athlete non-sprinters, on the other hand, conformed fairly closely to the spring-model predictions, even at their top speeds.”

Weyand said the new findings indicate that the classic spring model is not sufficient for understanding the mechanical basis of sprint running performance.

“We found all the fastest athletes applied greater ground forces with a common and apparently characteristic pattern that resulted from the same basic gait features,” he said. “What these sprinters do differently is in their wind up and delivery mechanics. The motion of their limbs in the air is distinct; so even though the duration of their limb-swing phase at top speed does not differ from other runners, the force delivery mechanism differs markedly.”

Sprinters have a common mechanical solution for speed — one that athletes who aren’t as fast do not execute.

“This provides scientific information so coaches and athletes can fully identify what to train,” Clark said. “It is our hope that our results can translate into advances in evidence-based approaches to training speed.”

The research was funded by the U.S. Army Medical Research and Materiel Command and SMU’s Simmons School of Education and Human Development. — Margaret Allen

Follow SMUResearch.com on twitter at @smuresearch.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.

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Lexington Herald-Leader: Cuban asks scientist to study physics of flopping

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Kentucky’s Lexington Herald-Leader covered the research of SMU biomechanics expert Peter G. Weyand, who is teaming with Dallas Mavericks owner Mark Cuban to investigate the forces involved in basketball collisions and the possibility of estimating “flopping” forces from video data.

Herald-Leader Journalist Jerry Tipton quoted Weyand in his June 15 UK basketball column on the flopping research, “Cuban asks scientist to study physics of flopping.

Flopping is a player’s deliberate act of falling, or recoiling unnecessarily from a nearby opponent, to deceive game officials. Athletes engage in dramatic flopping to create the illusion of illegal contact, hoping to bait officials into calling undeserved fouls on opponents.

The phenomenon is considered a widespread problem in professional basketball and soccer. To discourage the practice, the National Basketball Association in 2012 began a system of escalating fines against NBA players suspected of flopping, including during the playoffs, “NBA announces anti-flopping rules for playoffs.”

The Cuban-owned company Radical Hoops Ltd. awarded a grant of more than $100,000 to fund the 18-month research study at SMU.

Read the full story.

EXCERPT:
By Jerry Tipton
Herald-Leader

The defender might be a foot taller and 75 pounds heavier. Yet, contact with the smaller player sends him flying backward. When the referee calls charging, even a casual basketball fan senses injustice.

The illogic of these kiddie car-demolishes-pickup truck collisions moved Dallas Mavericks owner Mark Cuban to take action. He commissioned a scientific study of basketball’s all-too-common lapse into kabuki theatre: the offensive foul. Cuban, an unabashed critic of NBA officiating, had his company, Radical Hoops Ltd, donate $100,000 to Southern Methodist University to study the physics involved in these collisions, it was announced last week.

Peter Weyand, an associate professor of applied physiology and biomechanics at SMU, will lead what’s being billed as an 18-month investigation into mass, force and acceleration in baggy shorts. Sir Isaac Newton meets C.M. Newton.

Weyand and his team will try to determine how much force is required to “legitimately” knock a defender off his feet. They also hope to develop a metric to determine if such a force existed in any particular block/charge incident. In theory, a video review using this metric would lead to punishment for flopping.

Meanwhile, referees roll their eyes.

“Basketball officiating is an art,” said John Hampton, Kentucky native and Southeastern Conference official. “It is not a science. I am extremely skeptical of the whole project.”

Read the full story.

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For more information, www.smuresearch.com.

SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.

SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.