The key to an athlete's speed may be the body's center of gravity

What makes an athlete fast may have more to do with body type than training. Researchers from Duke University and Howard University think the secret may lie in the body's center of gravity.

Their study, released online in the International Journal of Design and Nature and Ecodynamics, may explain why the fastest sprinters are usually black, while the fastest swimmers are usually white, a difference that goes back decades. Though on the face of it this may seem like the differences are racial, the researchers believe they're really biological.

Blacks, they note, tend to have a slightly higher center of gravity than whites, due to having longer limbs with smaller circumferences. Because Asians and whites tend to have longer torsos, their centers of gravity are lower.

Those differences may translate into faster times in specific sports. Looking at other studies on the human body, the researchers deemed that, on average, blacks have about a 3% higher center of gravity than whites. That may make black sprinters 1.5% faster than white sprinters. Using that formula, whites may have a similar advantage over blacks in swimming. Asians may have an even greater advantage than whites in terms of center of gravity, they add, but that benefit is canceled out by the fact that they’re usually not as tall as white swimmers.

"Locomotion is essentially a continual process of falling forward," study co-author Adrian Bejan, in a news release. "Mass that falls from a higher altitude falls faster. In running, the altitude is set by the location of the center of gravity. For the fastest swimmers, longer torsos allow the body to fall forward farther, riding the larger and faster wave." Bejan is a professor of engineering at Duke's Pratt School of Engineering.

But the authors don't ignore the role that environment, as well as biology, may play in what athletes excel at.

"When I grew up in South Carolina, we were discouraged from swimming," Edward Jones, a co-author, said in a news release. Jones, who teaches at Howard University and is black, added, "There wasn't nearly as much encouragement for us as young people to swim as there was for playing football or basketball. With the right encouragement, this doesn't always have to be the case -- just look at the Williams sisters in tennis or Tiger Woods in golf."

-- Jeannine Stein

Photo: Jamaican sprinter Usain Bolt, left, is an Olympic medalist and world record holder. Photo credit: Fabrice Coffrini / AFP/Getty Images

Breast elevation could be the key to building a better sports bra

Large-breasted women often have trouble finding a sports bra that fits, is comfortable and keeps their breasts from jostling too much, causing pain. If you're one of those women, fear not. Scientists are trying to build you a better bra. They even produced a study about it.

Researchers at the University of Wollongong in New South Wales, Australia, tested three bra types on 20 women, average bra cup size DD, while they ran on a treadmill. One was an experimental bra designed to both compress and elevate the breasts, another was a commercial encapsulation sports bra and the third was a placebo bra. We're not really sure what a placebo bra is, but we're guessing Victoria's Secret won't have a version anytime soon.

Sports bras are typically designed to encapsulate or compress the breasts. Encapsulation bras give support to each breast via separate cups usually made of rigid material.They also frequently have a bra band made of sturdy elastic, and wide, padded straps.

Compression bras are made of elastic and push both breasts together against the chest wall. According to the study, encapsulation bras typically do a better job than compression bras of keeping breasts from moving too much, but they also tend to be uncomfortable. Hence the need for a better sports bra.

The study's experimental bra had the same basic structure of the commercial and placebo bras, but the stiff material in the cups was replaced with elastic rubber material that had greater stretch resistance and was designed to compress the breasts. High-density foam pads placed in the cups also elevated the breasts.

Breast movement relative to trunk movement was measured via markers placed near the neck and on the left heel. Movement was also measured with infrared light-emitting diodes placed on both nipples under each bra using double-sided surgical tape. It hurts just to write that.

Researchers measured vertical breast displacement relative to the torso, vertical breast velocity and breast compression and elevation. Participants were asked to rate bra fit comfort, breast discomfort and how much they thought their breasts moved.

All bras measured about the same for vertical breast displacement and breast velocity. However, breast elevation in the experimental bra was significantly better than the commercial and placebo bras. The runners reported less breast and bra discomfort while wearing the experimental bra compared with the other two bras.

Researchers believe that having the breasts more elevated might be the key to greater comfort, because elevation lessened the tension and loading on supportive breast tissues, not allowing them to stretch as much.

The study authors believe the findings may prove useful in developing new sports bras that are both functional and comfortable.

The study appears in the July issue of the journal Medicine & Science in Sports & Exercise.

-- Jeannine Stein

Photo: Finding a comfortable, supportive sports bra can be difficult for some women.

Body checks in youth ice hockey may put players at more risk of injury, study finds

Body checking in youth ice hockey is allowed in some American leagues, but the practice is controversial. A new study in the Journal of the American Medical Assn. finds that Canadian youth hockey leagues that allow body checking have a threefold increase of all game-related injuries compared to those that don't allow the practice.

The study, released today, compared 74 Canadian Pee-Wee teams of 11- and 12-year-olds (1,108 players) from Alberta to 76 Pee-Wee teams from Quebec (1,046). Alberta allows body checking for that age group, while Quebec does not. Body checking is a common hockey move in which the body is used to knock or slam an opponent against the ice or the rink boards. The move is not supposed to be done irresponsibly.

After examining the players' injuries for one season, they found that the Alberta players had 241 injuries, including 78 concussions. The Quebec teams had 91 injuries, including 23 concussions. There were no differences between the teams when it came to injuries suffered during practice.

Risk factors for injury and concussion included having suffered previous injuries and concussions, being smaller, and higher levels of play. Breaking down the injuries to body parts affected, Alberta players had more injuries to the head or face, followed by knee and shoulder or clavicle. Quebec players also had injuries most frequently to the head, face and knee, followed by the hip or thigh.

Body checking in youth hockey is introduced in U.S. leagues for 11- and 12-year-olds, but some leagues do not permit body checking. The American Academy of Pediatrics issued a policy statement in 2007 (that was reaffirmed in 2010) on safety in youth hockey that included this recommendation: "Body checking should not be allowed in youth hockey for children age 15 years or younger."

And while other studies have shown body checking to produce substantial injuries, a study in 2005 in the journal Medicine & Science in Sports & Exercise found that for youth hockey players, accidental collisions and falling into the boards produced more injuries than body checking.

-- Jeannine Stein

Photo: Body checking in ice hockey may lead to serious injuries. Credit: Robert Lachman / Los Angeles Times

Studies put the squeeze on athletic compression garments

Compression garments are popular with some athletes, such as runners and basketball players, who think the tight-fitting clothing lends a competitive edge. But that may not be the case, according to two new studies presented Thursday at the annual meeting of the American College of Sports Medicine being held in Baltimore.

One study looked at the effect on oxygen consumption among 16 trained male distance runners who wore lower leg compression sleeves. The sleeves, socks that run from just above the ankle to just below the knee, were worn by the runners during a 12-minute running test. The athletes also did the test without the sleeves.

Oxygen consumption did not change significantly in either test. However, small variations were noted--four runners had greater than 1% average increase in oxygen consumption, which means they ran less efficiently. Four runners also had a greater than 1% average decrease in oxygen consumption. There was no change in running mechanics.

Abigail Laymon, the study's lead author and a researcher in the department of kinesiology at Indiana University, also gave the athletes a questionnaire asking their feelings about the compression sleeves. Those who had better outcomes with were more likely to have a favorable attitude about the garments and thought their racing would improve while wearing them.

"Overall, with these compressive sleeves and the level of compression that they exert, they don't seem to really do much," Laymon said in a news release. "However, there may be a psychological component to compression’s effects. Maybe if you have this positive feeling about it and you like them then it may work for you. It is a very individual response."

The other study focused on upper thigh compression garments. Researcher and lead author Nathan Eckert, a human performance doctoral student in the department of kinesiology at Indiana University, tested three types of compression garments on 25 men who did vertical jumps. Each test subject did the jumps while wearing a waist-to-knee garment that fit exactly, one that was a size smaller, and one that was a size larger.

No differences were noted in jump height. "We looked at various different angles to see if the variability changed and nothing significant happened," Eckert said in a news release. "This basically states that at all three different levels of compression did absolutely nothing for them."

-Jeannine Stein

Compression garments, such as this one worn by basketball player Monique Currie, are popular with some athletes. Photo credit: Jon Gardiner / Duke Photography

Disadvantaged children may fall short in basic motor skills

Disadvantaged kids may struggle more in the classroom, but they also might face hurdles on the playground as well.

A new study finds that the vast majority of underprivileged preschoolers who were tested scored below the 30th percentile of children across the U.S. That ranking is considered developmentally disabled.

Researchers studied 469 preschoolers who were enrolled in urban, state-funded programs that assist disadvantaged kids. Of that group, 275 were mostly African American and from a city in the Midwest, and 194 were mostly Hispanic and from a southwestern city.

The boys and girls were given standardized motor skill tests, both for locomotor ability (running, jumping, skipping, leaping) and object control skills (throwing, kicking, rolling, catching).

Average scores for both skill tests showed 86% of the children had developmental delays at or below the 30th percentile. When the data was broken down by gender, boys routinely scored higher than girls. Although there was no control group to which the researchers compared scores, they believe the results are dramatic enough to warrant interventions, as well as more understanding of gender disparities.

"These fundamental motor skills -- running and catching and throwing and kicking -- are the movement ABCs," said Jackie Goodway, the study's lead author, in a news release. Goodway, associate professor of physical activity and educational services at Ohio State University, added, "If children don't learn the ABCs, they can't read. And if they don't learn basic motor skills they won't participate in sports or exercise. That's the problem we may be facing with the children in this study."

Goodway added that while most people may believe that children naturally develop motor skills, she believes that's not always the case. "Like any skill," she said, "there needs to be instruction, there needs to be practice, there needs to be feedback. That's how children master these motor skills."

The study appears in the March issue of the journal Research Quarterly for Exercise and Sport.

-- Jeannine Stein

Photo: Mark Boster / Los Angeles Times

Technology may help injured marathoners

Marathons and ultra races have been steadily growing in popularity in recent years. But added participants could mean more injuries and serious incidents such as heart attacks. During the Los Angeles Marathon last month, 21-year-old Jay Yim suffered a heart attack at mile 18, but quick action by a police officer, a doctor and others no doubt saved his life.

That and other marathon catastrophes have gotten people thinking about how to better care for runners. At last year's Detroit Free Press Marathon a new system of electronic medical records made its debut. The volunteer medical staff kept track of data on runners and spectators who needed medical assistance during the race, and military grade laptops were stationed at every remote first aid station as well as the central medical location. The mobile medical coordination center had an electronic event board that could be seen by the medical command staff.

Dr. Christopher Guyer, an athletic medicine physician at Henry Ford Hospital in Detroit, was the lead researcher on a study testing the new system. Data on the runners were secure, and they were identified by bib numbers or other anonymous tags to protect their identity.

At the marathon, 216 runners and spectators were treated. The average age was 37.6, and four people were brought to area hospitals. Treatment was concentrated at the start or finish line, the mile 11 station, and the mile 15 station. Three runners collapsed and died during the race.

It's too soon to tell what precise effects the new program had, says Guyer--that may come later when they can analyze a few years' worth of data.

"What we can say right now," he said, "is that there were several examples where we were aided in communication—we were able to tell people where they could find family members who were racers, if they had been transported to a hospital. It made it easier for people to figure out what was going on." More efficient interaction is a big plus, he added, especially at events like these that draw tens of thousands of runners and observers.

After collecting data from a few races, however, Guyer hopes race providers will be better prepared to handle serious problems such as heart attacks by placing doctors, physical therapists and other medical staff, plus defibrillators, at key points along the route.

Guyer presented his findings at the recent annual meeting of the American Medical Society for Sports Medicine in Cancun, Mexico.

-- Jeannine Stein

Photo credit: Luis Sinco / Los Angeles Times

Sports stars' drinking habits don't influence others

Sports stars are greatly admired in the United States and many other countries, which raises the question of whether fans may try to emulate their behavior. That could be a problem when you think about the high-profile sports figures whose behavior is abominable. On Wednesday, the National Football League commissioner suspended Pittsburgh Steelers quarterback Ben Roethlisberger for violating the league's personal conduct policy (a result of a recent allegation of sexual assault in a bar).
 
A new study, however, concludes that sports stars' behavior has no effect on the drinking habits of young people. Researchers in the United Kingdom and Australia polled more than 1,000 young people on how they perceive the drinking behavior of sports stars compared with their friends'. They were also asked to report their own drinking patterns. The poll included both athletes and people uninterested in sports.
 
Researchers found that both the sporting and non-sporting people both thought their friends probably drank significantly more than themselves and that sports stars probably drank significantly less. Overestimating the amount another person, such as a peer or role model, drinks has been shown to influence heavier drinking. Thus, in this study, young people appeared to be more influenced by their perceptions of how much their friends drink.
 
"Sports administrators, like the Football Association, are very quick to condemn and punish individual sport stars for acting as poor role models when they are caught displaying drunken and loutish behavior," the lead author of the study, Dr. Kerry O'Brien of the University of Manchester, said in a news release. "But there is much stronger evidence for a relationship between alcohol-industry sponsorship, advertising and marketing within sport and hazardous drinking among young people than there is for the influence of sports stars drinking."
 
Sports stars shouldn't be encouraged to behave like drunken fools, but neither should they be blamed for setting a bad example, O'Brien said. Instead, he said, it's the marketing of alcohol surrounding sports events that should be addressed. The study was published online Wednesday in the journal Drug and Alcohol Review.
 
-- Shari Roan
 
Photo: A fan wearing a Pittsburgh Steelers quarterback Ben Roethlisberger jersey holds up a sign while attending the baseball game between the Milwaukee Brewers and the Pittsburgh Pirates in Pittsburgh on Wednesday. The NFL announced the decision to suspend Roethlisberger for six games in the 2010 season for violating the NFL personal-conduct policy. Credit: Keith Srakocic  /  Associated Press

The Extremity Games: For disabled athletes, it's all about the competition

No doubt you know about the X Games, but you've probably never heard of the Extremity Games. Like the X Games, events include extreme sports such as motocross and skateboarding. But this extreme competition is only for disabled athletes who have lost a limb or have limb differences.

The Extremity Games started in 2006, and in addition to motocross and skateboarding, sports include wakeboarding, rock climbing, kayaking, mountain biking and martial arts. In May there's a motocross elite competition in Michigan; the main event is in June in Texas; and in September the wakeboarding elite competition takes place in Florida. The games are organized by the Athletes With Disabilities Network, which is a subsidiary of Easter Seals-Michigan.

Chris Ridgway is a motocross racer from Apple Valley who competes in both the Extremity Games as well as in adaptive events for disabled athletes in the X Games. Ridgway, who was profiled on the Outposts blog in 2009, elected to have his left leg amputated below the knee in 2002 after suffering substantial injuries while doing motocross (he's been competing since the early 1990s). Before the amputation he used a wheelchair and endured tremendous pain. Although he says he's not in this to be an inspiration to others, he is by default. "This is the hand I was dealt," he says, "and I've just got to deal with it. I'm pretty sure the other athletes feel the same way."

Of his fellow Extremity Gamers, Ridgway says: "They have the most amazing stories that would literally make you cringe, but at the same time they're not saying, 'Woe is me, I'm down in the dumps.' They work hard and they still go through a lot of pain, but they're doing what they want to do. It's the whole atmosphere around the games that I really love."

He treats the Extremity Games no differently from any other competition. For his first event in 2007 he quit his job and trained intensely for seven months so he could come away with the gold medal. And he did. He now has three golds.

"I'm not special," he says. "Anybody can do this."

Ridgway, who wears a prosthetic leg while racing, recommends that those attending the upcoming Extremity Games talk to the competitors: "It's a story about never giving up," he says. "I can't stand people in my life who are quitters, and that's why I like the athletes in the Extremity Games. They just keep trying."

-- Jeannine Stein

Photo: Chris Ridgway on his motorbike during a practice. Credit: Steve Cox

A happy ending to a marathon nightmare [updated]

Running the recent Los Angeles Marathon was a triumph for thousands of people who made it through 26.2 miles of city streets. But for one runner, Jay Yim, the day didn't exactly go as planned.

Yim, 21, suffered a heart attack around mile 18 and was rushed to the Ronald Reagan UCLA Medical Center via ambulance in what appears to be the worst casualty of the race (it was reported that about 30 other runners were hospitalized). Yim is listed in good condition and is expected to make a full recovery.

Here's how things went down: After Yim collapsed in West L.A., LAPD motorcycle officer Joshua Sewell, who cut his vacation short to volunteer at the race, was one of the first people to come to Yim's aid. Yim was about the fourth person he'd seen hit the pavement that day, he said, from exhaustion or dehydration. But when he tried to revive Yim he got no response and found no pulse. Sewell yelled for someone to call an ambulance and recruited an LAPD bicycle officer to help administer CPR. "I did CPR in the [police] academy 15 years ago but not since then," he said. The lapse didn't seem to matter -- the routine kicked in and chest compressions and mouth-to-mouth resuscitation were done with precise timing.

Also on the scene was Dr. Charles Chandler, chief of surgery at Santa Monica-UCLA Medical Center, who was watching the marathon from near his home and saw Sewell running by. "When I got there Jay was in the middle of the street -- completely still, and his pupils were dilated and he wasn't moving any air." Chandler helped out with CPR, eventually getting a pulse, and called UCLA's emergency room to tell the staff the ambulance was on its way.

After undergoing tests, it was discovered that Yim had suffered some seizures as well, possibly caused by the cardiac arrest, said Dr. Paul Vespa, director of Neurocritical Care at UCLA, who treated Yim. An MRI showed some brain swelling, and fearing brain injuries hypothermia was induced. In that process, the body is cooled to 32 degrees Celsius [Update: An earlier version said Fahrenheit. The 32 degrees Celsius equals 89.6 degrees Fahrenheit] (the procedure is also used for some cardiac arrest cases) and is in a coma. The process, still somewhat controversial, basically brings on hibernation, Vespa said, causing a metabolism shutdown. "When you have a brain injury," he said, "a whole number of bad pathways get activated, and that can lead to cell death and damage. Hypothermia blocks those pathways." He added that hypothermia can also put the body at higher risk for infection, since the immune system is suppressed.

Yim's body was warmed after about 48 to 72 hours, and he is now awake and talking. He's undergoing physical therapy, and while Vespa said it's too soon to tell if Kim will ever do another marathon, his overall prognosis is excellent. What caused his cardiac arrest still isn't known, and although it's unusual for someone his age and good health to suffer a heart attack, dehydration or inadequate nutrition during a marathon or other physical activity can trigger such catastrophic events.

But Yim, a USC pre-med student originally from Phoenix, has some incentive to run again. Sewell, who ran the marathon in 2006, said he promised he'll finish the last 8.2 miles with Yim when he's able. "I told him that, and he got a big old smile on his face," Sewell said, adding that he’s been spending a lot of time with Yim and his family. "I got a little emotionally attached to this one."

"Everything was in Jay's favor," said Yim's older brother Roy, a law student from Florida. "It's weird how it all turned out."

-- Jeannine Stein

Photo credit: Spencer Weiner / Associated Press

Cooling jackets - the best way for athletes to feel the chill?

Cooling jackets are often used by athletes to chill their core body temperature before, during or after exercise. The jackets' cooling properties take the edge off extreme heat, possibly avoiding hyperthermia. While in theory they sound like a good idea, do they work?

A group of researchers from the University of Western Australia and the Western Australian Institute of Sport decided to find out, testing 12 active young men in three different conditions. The men exercised for a half-hour at 75% of their maximum ability in a controlled environment where the temperature was about 95 degrees with 52% relative humidity. Afterward they spend 30 minutes in cooler temperatures.

During that cooling period the participants were randomly assigned to wear a gel-based cooling jacket, a jacket made with phase change material, which absorbs the body's excess heat, or no jacket at all (this served as a control).

Skin temperatures and core temperatures at the beginning of the exercise period and during it didn't vary much among the participants. More important, there was very little variation in skin or core temperature cooling among the three conditions.

The researchers noted that while there were virtually no differences between the jackets in terms of cooling, the jacket with the phase change material may warrant more study, since it can stay colder at higher temperatures than some other materials and can sustain a steady temperature during use.

The study appears in the April issue of the Journal of Athletic Training.

-- Jeannine Stein

Photo credit: Reed Saxon / Associated Press