Tag: Peter Weyand

By Kelly Dickerson
Science.mic
Sprinter Usain Bolt of Jamaica just made history by winning his third straight gold medal in the men’s 100-meter dash — something no runner has done before.

How does Bolt keep doing it?

Bolt doesn’t win by moving his legs faster than everyone else. At the Olympic level, there are much more important factors that contribute to speed, and Bolt has figured out how to capitalize on them.

The key to sprinting isn’t a quicker stride, according to research by Peter Weyand, a professor of applied physiology and biomechanics at Southern Methodist University. It comes down to the amount of force a runner can apply to the ground, as well as how long they leave their feet on the ground per step.

Case in point: Studies have found the average runner applies about 500 to 600 pounds per step. An Olympic runner applies upward of 1,000 pounds. The average runner has their foot on the ground for 0.12 seconds per step, according to the Post Game. An Olympic runner has it there for less than a tenth of a second.

Bolt is really tall — he stands at 6 feet, 5 inches. Normally, that height would be a disadvantage, Weyand explained.

“Shorter individuals are advantaged coming out of the blocks and over the initial 5 to about 15 meters of the race,” Weyand said in an email. “Shorter runners have less mass to move, so the ground force needed to accelerate the body is not as great. So although Bolt is not the best starter in the world, he loses relatively little ground versus what science indicates he should.”

“Although Bolt is not the best starter in the world, he loses relatively little ground versus what science indicates he should.”

After the start of the race, Bolt’s height becomes a major advantage for two reasons, according to Weyand:

By Rachel Brady
The Globe and Mail
It’s hard to explain, but experts would love to try. Canadian sprinter Andre De Grasse, at 5-foot-9 and 154 pounds and with a running style that has his right arm flying behind him, doesn’t fit the conventional mold of a world class sprinter, reports Rachel Brady. So why’s he so fast?

Some experts in the biomechanics of sport have been watching Canada’s rising track star, Andre De Grasse, with fascination, dreaming of what it would be like to get the speedy phenom into their labs to find out how the first-time Olympian with the unconventional style runs so fast.

The 5-foot-9, 154-pound sprinter is shorter and less muscular than most of his opponents. He doesn’t start races out of the blocks particularly well, and as he flies down the track, his right arm swings backward in a quirky sort of way. To boot, the 21-year-old youngster took up sprinting less than four years ago. Yet De Grasse, who ran the 100-metre dash in 9.91 seconds to capture an Olympic bronze medal on Sunday, is defying many conventional beliefs about how a world-class sprinter should look and move.

The youngster from Markham, Ont., repeatedly pumps his outstretched right arm behind him when hitting his top speed during a race; meanwhile his left arm is bent and pumping in a more typical way.

The asymmetry is in sharp contrast to most of his opponents, who typically pump bent arms at both sides. De Grasse told a reporter from the International Association of Athletics Federations website last year that he attributes that extended right arm swing to an imbalance in his hips caused by a minor basketball injury in his childhood.

The experts say it’s no surprise that De Grasse is being left to run the way he’s most comfortable.

… One expert with experience testing world-class sprinters in a locomotor performance lab says arms have little effect on what is most important to elite sprinting – ground-reaction forces.

“His arm swing is not at all consequential to performance,” said Peter Weyand, professor of applied physiology and biomechanics at Southern Methodist University in Dallas, Texas. “The arms are light pendulums that allow runners to stay balanced as they execute strides. Differences in the arm’s motion and how it’s angled at the elbow really doesn’t matter to the sprinter’s velocity and the interaction between the feet and the ground. Some of the old guard still think arm motion really matters, but most today realize it’s not that consequential. The old guard might have tried to bend a sprinter’s elbow into place, but they wouldn’t have been able to offer much scientific data about why they were doing it.”

By Matt Porter
The Roar
We’ve just watched the incomparable Usain Bolt ensure his immortality as the greatest sprinter of all time with his third successive 100m Olympic Gold medal in Rio.

The world rejoiced and the embattled Rio Olympics organisers and IAAF breathed a sigh of relief as the Great Jamaican ran down twice convicted doping cheat Justin Gatlin to claim his rightful place in the Olympic pantheon.

The triumph came barely half an hour after South African Wayde van Niekerk smashed Michael Johnson’s 17-year-old 400m world record to beat home a star-studded field in the final of that event to scorch the lap in 43.03s, a whopping 0.15s faster than the old mark.

What an hour for the fastest humans on the planet. 

The 100m final is my favourite nine and a bit seconds of any Olympic Games. So primal. So raw. No other modes of transport involved. No distance to endure, water to splash through or bends in the track to negotiate. No racquets, bats, clubs or balls. Just the fastest of a land-based mammal species attempting to out-run one another from start to finish over a very short distance in a straight line.

…Peter Weyand, a biomechanics professor at Southern Methodist University in Dallas is a leading expert in human locomotion. He reckons the primary factor influencing speed is how much force sprinters hit the ground with their feet.

When athletes run at a constant speed they use their limbs like pogo sticks, Weyand says. Once a sprinter hits the ground, his limb compresses and gets him ready to rebound. When he’s in the air, the feet get ready to hit the ground again.

Every time a runner hits the ground, 90 per cent of the force goes vertically to push him or her up again, while only 5 per cent propels him or her horizontally. In that regard, sprinters behave a lot like one of those super bouncy balls you play with as a kid, Weyand says. “They bounce a lot.” 

Our body naturally adjusts to how fast we run by changing how hard we hit the ground. The harder we hit the ground, the faster we go.

So just how hard can humans hit the ground while they run?