Category: Health & Medicine

A Nov. 12 article on MSNBC cites the research of SMU physiologist and biomechanist Peter Weyand in which he and other scientists found that everyone uses about the same amount of energy when they walk, but short people use more energy over a given distance. The reason: people with shorter legs take more steps to cover the same distance as people with longer legs.

Weyand says the study has clinical applications and weight balance applications. In addition, the military is interested too because metabolic rates influence the physiological status of soldiers in the field, he said.

Read the full story.

Also covering the research is UPI, with the story Equation calculates energy cost of walking.

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.

Excerpt:

By Rachel Rettner
MSNBC
Scientists have come up with a new equation to determine how much energy people actually use while walking.

While previous work has conjured many ways to measure the energy cost of walking, the new equation is among the first to account for the impact of body size, taking into account individuals’ height and weight.

The equation has many possible applications. It could be used to design pedometers that, in addition to distance walked, provide an estimate of calories burned, taking into account a person’s body size. The military may also find the equation handy, possibly using it to calculate how much energy soldiers expend — and thus how many calories they will need — while carrying different loads, said study researcher Peter Weyand, of Southern Methodist University in Dallas.

The findings are published today (Nov. 12) in the Journal of Experimental Biology.
Why height and weight matter .

Scientists knew that shorter people, including children, use up more energy per pound of their body mass when walking than taller people, but they didn’t know why.

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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.

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.

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.

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.

Read the full story.

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.
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