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Back in high school, on the soccer field, poised to take a crucial penalty kick, “I always had a lot of thoughts going on in my head; I think most people do” says sports psychologist Antonis Hatzigeorgiadis. “I was setting the ball and planning my shot; I was the captain and never missed those types of shots; then I had that thought striking me that it was not going to be good. I knew I was going to miss,” he recalls, “and I did miss.” Even then, he could see that his mind had a big effect on his body.
From these unhappy experiences evolved Hatzigeorgiadis’ interest in the psychology of sport – the link between one’s thoughts and performance, and specifically in “self-talk”— the mental strategy that aims to improve performance through the use of self-addressed cues (words or small phrases), which trigger appropriate responses and action, mostly by focusing attention and psyching-up.
“We know this strategy works, and it works in sports,” says Hatzigeorgiadis. But what makes it work better, and in what situations? To find out, Hatzigeorgiadis and his colleagues at the Department of Physical Education and Sport Sciences at the University of Thessaly, Nikos Zourbanos, Evangelos Galanis, and Yiannis Theodorakis conducted a meta-analysis of 32 sport psychological studies on the subject with a total of 62 measured effects. Their findings will be published in an upcoming issue of Perspectives on Psychological Science, a journal of the Association for Psychological Science.
As expected, the analysis revealed that self-talk improves sport performance.
But the researchers teased out more – different self-talk cues work differently in different situations. For tasks requiring fine skills or for improving technique “instructional self-talk”, such as a technical instruction (“elbow-up” which Hatzigeorgiadis coaches beginner freestyle swimmers to say) is more effective than ‘motivational self-talk’ (e.g., “give it all”), which seems to be more effective in tasks requiring strength or endurance, boosting confidence and psyching-up for competition. Thus, we should carefully design the self-talk athletes use according to needs.
Some other findings are that self-talk has a greater effect on tasks involving fine skills (such as sinking a golf ball) rather than gross skills (e.g., cycling); probably because self-talk is a technique which mostly improves concentration. Self-talk is more effective for novel tasks rather than well-learned tasks; because it is easier to improve at the early steps of learning. Nevertheless, both beginners and experienced athletes can benefit, especially when they practice the self-talk technique.
Most important, says Hatzigeorgiadis, is that athletes train to self-talk—they prepare their scripts and use them consistently in training under varying conditions to better prepare themselves for competition.
The main goals behind self-talk—like other techniques such as visualization to “rehearse” a performance or meditation to improve focus and relaxation—are twofold, says Hatzigeorgiadis: “to enhance your potential; and to perform during competition in terms of your ability and not less.”
The meta-analysis can help sports psychologists and athletes refine their training. But the strategy has implications beyond the playing field. “The mind guides action. If we succeed in regulating our thoughts, then this will help our behavior,” says Hatzigeorgiadis.
“The goal of being prepared is to do the best you can do.”
Thursday, May 26, 2011
Friday, March 11, 2011
Off the Backboard Shots Better Bet
The Physics of Bank Shots
Released: 3/10/2011 3:45 PM EST
Source: North Carolina State University
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New research by engineers at North Carolina State University show that you had a better chance of scoring that particular game-winning bucket with a bank shot than with a direct shot.
After simulating one million shots with a computer, the NC State researchers show that the bank shot can be 20 percent more effective when shooting at many angles up to a distance of about 12 feet from the basket. Bank shots are also more effective from the “wing” areas between the three-point line and the free-throw lane. However, straight-on shots – those corresponding to the area around the free-throw line – from further than 12 feet are not as well suited for bank shots.
The researchers also found the optimal points where the simulated made baskets were aimed. The results show the optimal aim points make a “V” shape near the top center of the backboard’s “square,” which is actually a 24-inch by 18-inch rectangle which surrounds the rim. Away from the free-throw lane, these aim points were higher on the backboard and thus further from the rim. From closer to the free-throw lane, the aim points were lower on the backboard and closer to the rim.
The researchers also discovered that if you imagine a vertical line 3.327 inches behind the backboard and found where it crossed the aim point on the “V” shape on the backboard, you’d find the optimal spot to bank the basketball to score a basket.
“Basketball players can’t take a slide rule out on the court, but our study suggests that a few intuitive assumptions about bank shots are true,” says Dr. Larry Silverberg, professor of mechanical and aerospace engineering at NC State and the lead author of a paper describing the research. “They can be more effective than direct shots, especially from certain areas of the court – and we show which areas on the court and where the ball needs to hit the backboard.”
The researchers made a few assumptions while conducting the study. They used a men’s basketball, which is slightly bigger and heavier than a women’s basketball; launched the simulated shots from 6, 7, and 8 feet above the ground; and imparted 3 hertz of backspin – which means three revolutions per second – on the shots. The latter variable was shown in previous research to be optimal for successfully converting a free throw.
Released: 3/10/2011 3:45 PM EST
Source: North Carolina State University
Ω
New research by engineers at North Carolina State University show that you had a better chance of scoring that particular game-winning bucket with a bank shot than with a direct shot.
After simulating one million shots with a computer, the NC State researchers show that the bank shot can be 20 percent more effective when shooting at many angles up to a distance of about 12 feet from the basket. Bank shots are also more effective from the “wing” areas between the three-point line and the free-throw lane. However, straight-on shots – those corresponding to the area around the free-throw line – from further than 12 feet are not as well suited for bank shots.
The researchers also found the optimal points where the simulated made baskets were aimed. The results show the optimal aim points make a “V” shape near the top center of the backboard’s “square,” which is actually a 24-inch by 18-inch rectangle which surrounds the rim. Away from the free-throw lane, these aim points were higher on the backboard and thus further from the rim. From closer to the free-throw lane, the aim points were lower on the backboard and closer to the rim.
The researchers also discovered that if you imagine a vertical line 3.327 inches behind the backboard and found where it crossed the aim point on the “V” shape on the backboard, you’d find the optimal spot to bank the basketball to score a basket.
“Basketball players can’t take a slide rule out on the court, but our study suggests that a few intuitive assumptions about bank shots are true,” says Dr. Larry Silverberg, professor of mechanical and aerospace engineering at NC State and the lead author of a paper describing the research. “They can be more effective than direct shots, especially from certain areas of the court – and we show which areas on the court and where the ball needs to hit the backboard.”
The researchers made a few assumptions while conducting the study. They used a men’s basketball, which is slightly bigger and heavier than a women’s basketball; launched the simulated shots from 6, 7, and 8 feet above the ground; and imparted 3 hertz of backspin – which means three revolutions per second – on the shots. The latter variable was shown in previous research to be optimal for successfully converting a free throw.
Tuesday, March 1, 2011
For Hitters on Deck, Warm-Up Devices Don't Increase Bat Speed
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Player Preference Should Determine Warm-Up Routine, Reports The Journal of Strength and Conditioning Research
Donuts, bat wraps, weighted gloves…a wide array of devices are available to help baseball players warm up while waiting to go to bat. But a new study finds that none of ten commonly used warm-up devices has a significant effect on bat speed, reports the February issue of The Journal of Strength and Conditioning Research, official research journal of the National Strength and Conditioning Association.
"Furthermore, heavier warm-up devices did not provide greater bat velocity than the 'standard' bat or lighter devices," according to the new study, led by David J. Szymanski, PhD, CSCS*D, RSCC*D, of Louisiana Tech University, Ruston. They believe their results, combined with previous studies, have implications for recommended warm-up routines for batters in the on-deck circle.
Ten Different Warm-Up Devices Show No Difference in Bat Speed
In the study, 22 Division I college baseball players were tested using various devices designed for use in warming-up before batting. The devices ranged from a simple "donut ring," to weighted bat wraps and gloves, to special warm-up bats. The weight of the warm-up devices ranged from 22 to 96 ounces.
At each testing session, the players took three practice swings, as hard as possible, using one of the ten devices. Then, using a standard game bat (33 inches, 30 ounces), they hit a baseball off a tee, attempting to generate maximum bat velocity. A special device was used to measure the velocity of the bat head to see if any of the different warm-ups led to a significant change in bat speed.
Bat speed is thought to be an important component of hitting performance. "The idea is that swinging a heavy warm-up device in the on-deck circle will increase players’ bat velocity with their game bat when attempting to hit the baseball during an at-bat," Dr. Szymanski and co-authors explain. "If bat velocity is increased, this will allow the exit velocity of the batted ball to be greater, resulting in the baseball being hit farther."
In the study, however, none of the ten warm-up devices led to a significant increase (or decrease) in average bat velocity. Bat speed was no different when the players warmed up using heavier versus lighter devices, or with their usual game bat alone.
From Little League to the Big Leagues, batters in the on-deck circle use a variety of weighted devices to warm up for their turn at bat. Some previous studies have suggested that warming up with a heavier bat may lead to perceptual distortion, or a "kinesthetic aftereffect." Warming up with a weighted bat may make the standard bat feel lighter, providing the player with a psychological advantage.
However, the new report finds no evidence that any type of warm-up device affects objectively-measured bat velocity. "This study suggests that Division I intercollegiate players interested in having the highest bat velocity during a game at-bat can use any of the ten implements tested," Dr. Szymanski and co-authors write.
They note that their result differs from some previous baseball research—including a study by DeRenne and colleagues, which found that warming up with a weighted bat of plus or minus twelve percent (4 ounces) of game bat weight produced the greatest bat velocity (in high school players). Other studies have suggested that using a device that adds weight to the top of the bat, such as a donut or wrap, may actually slow bat speed. Dr. Szymanski comments, "Thus we'd suggest that, if players use a warm-up device, they should follow the recommendations of DeRenne and colleagues and use a weight within twelve percent of their standard game bat, and that the weight should be evenly distributed."
Player Preference Should Determine Warm-Up Routine, Reports The Journal of Strength and Conditioning Research
Donuts, bat wraps, weighted gloves…a wide array of devices are available to help baseball players warm up while waiting to go to bat. But a new study finds that none of ten commonly used warm-up devices has a significant effect on bat speed, reports the February issue of The Journal of Strength and Conditioning Research, official research journal of the National Strength and Conditioning Association.
"Furthermore, heavier warm-up devices did not provide greater bat velocity than the 'standard' bat or lighter devices," according to the new study, led by David J. Szymanski, PhD, CSCS*D, RSCC*D, of Louisiana Tech University, Ruston. They believe their results, combined with previous studies, have implications for recommended warm-up routines for batters in the on-deck circle.
Ten Different Warm-Up Devices Show No Difference in Bat Speed
In the study, 22 Division I college baseball players were tested using various devices designed for use in warming-up before batting. The devices ranged from a simple "donut ring," to weighted bat wraps and gloves, to special warm-up bats. The weight of the warm-up devices ranged from 22 to 96 ounces.
At each testing session, the players took three practice swings, as hard as possible, using one of the ten devices. Then, using a standard game bat (33 inches, 30 ounces), they hit a baseball off a tee, attempting to generate maximum bat velocity. A special device was used to measure the velocity of the bat head to see if any of the different warm-ups led to a significant change in bat speed.
Bat speed is thought to be an important component of hitting performance. "The idea is that swinging a heavy warm-up device in the on-deck circle will increase players’ bat velocity with their game bat when attempting to hit the baseball during an at-bat," Dr. Szymanski and co-authors explain. "If bat velocity is increased, this will allow the exit velocity of the batted ball to be greater, resulting in the baseball being hit farther."
In the study, however, none of the ten warm-up devices led to a significant increase (or decrease) in average bat velocity. Bat speed was no different when the players warmed up using heavier versus lighter devices, or with their usual game bat alone.
From Little League to the Big Leagues, batters in the on-deck circle use a variety of weighted devices to warm up for their turn at bat. Some previous studies have suggested that warming up with a heavier bat may lead to perceptual distortion, or a "kinesthetic aftereffect." Warming up with a weighted bat may make the standard bat feel lighter, providing the player with a psychological advantage.
However, the new report finds no evidence that any type of warm-up device affects objectively-measured bat velocity. "This study suggests that Division I intercollegiate players interested in having the highest bat velocity during a game at-bat can use any of the ten implements tested," Dr. Szymanski and co-authors write.
They note that their result differs from some previous baseball research—including a study by DeRenne and colleagues, which found that warming up with a weighted bat of plus or minus twelve percent (4 ounces) of game bat weight produced the greatest bat velocity (in high school players). Other studies have suggested that using a device that adds weight to the top of the bat, such as a donut or wrap, may actually slow bat speed. Dr. Szymanski comments, "Thus we'd suggest that, if players use a warm-up device, they should follow the recommendations of DeRenne and colleagues and use a weight within twelve percent of their standard game bat, and that the weight should be evenly distributed."
Friday, February 18, 2011
Stretching before a run does not prevent injury
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However, runners who typically stretch should continue, or risk injury
Stretching before a run neither prevents nor causes injury, according to a study presented today at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS).
More than 70 million people worldwide run recreationally or competitively, and recently there has been controversy regarding whether runners should stretch before running, or not at all. This study included 2,729 runners who run 10 or more miles per week. Of these runners, 1,366 were randomized to a stretch group, and 1,363 were randomized to a non-stretch group before running. Runners in the stretch group stretched their quadriceps, hamstrings, and gastrocnemius/soleus muscle groups. The entire routine took 3 to 5 minutes and was performed immediately before running.
The study found that stretching before running neither prevents nor causes injury. In fact, the most significant risk factors for injury included the following:
history of chronic injury or injury in the past four months;
higher body mass index (BMI); and
switching pre-run stretching routines (runners who normally stretch stopping and those who did stretch starting to stretch before running).
"But, the more mileage run or the heavier and older the runner was, the more likely he or she was likely to get injured,"
"As a runner myself, I thought stretching before a run would help to prevent injury," said Daniel Pereles, MD, study author and orthopaedic surgeon from Montgomery Orthopedics outside Washington, DC. "However, we found that the risk for injury was the same for men and women, whether or not they were high or low mileage runners, and across all age groups. But, the more mileage run or the heavier and older the runner was, the more likely he or she was likely to get injured, and previous injury within four months predisposed to even further injury," he added.
Runners who typically stretch as part of their pre-run routine and were randomized not to stretch during the study period were far more likely to have an injury. "Although all runners switching routines were more likely to experience an injury than those who did not switch, the group that stopped stretching had more reported injuries, implying that an immediate shift in a regimen may be more important than the regimen itself," he added.
The most common injuries sustained were groin pulls, foot/ankle injuries, and knee injuries. There was no significant difference in injury rates between the runners who stretched and the runners who didn't for any specific injury location or diagnosis.
However, runners who typically stretch should continue, or risk injury
Stretching before a run neither prevents nor causes injury, according to a study presented today at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS).
More than 70 million people worldwide run recreationally or competitively, and recently there has been controversy regarding whether runners should stretch before running, or not at all. This study included 2,729 runners who run 10 or more miles per week. Of these runners, 1,366 were randomized to a stretch group, and 1,363 were randomized to a non-stretch group before running. Runners in the stretch group stretched their quadriceps, hamstrings, and gastrocnemius/soleus muscle groups. The entire routine took 3 to 5 minutes and was performed immediately before running.
The study found that stretching before running neither prevents nor causes injury. In fact, the most significant risk factors for injury included the following:
history of chronic injury or injury in the past four months;
higher body mass index (BMI); and
switching pre-run stretching routines (runners who normally stretch stopping and those who did stretch starting to stretch before running).
"But, the more mileage run or the heavier and older the runner was, the more likely he or she was likely to get injured,"
"As a runner myself, I thought stretching before a run would help to prevent injury," said Daniel Pereles, MD, study author and orthopaedic surgeon from Montgomery Orthopedics outside Washington, DC. "However, we found that the risk for injury was the same for men and women, whether or not they were high or low mileage runners, and across all age groups. But, the more mileage run or the heavier and older the runner was, the more likely he or she was likely to get injured, and previous injury within four months predisposed to even further injury," he added.
Runners who typically stretch as part of their pre-run routine and were randomized not to stretch during the study period were far more likely to have an injury. "Although all runners switching routines were more likely to experience an injury than those who did not switch, the group that stopped stretching had more reported injuries, implying that an immediate shift in a regimen may be more important than the regimen itself," he added.
The most common injuries sustained were groin pulls, foot/ankle injuries, and knee injuries. There was no significant difference in injury rates between the runners who stretched and the runners who didn't for any specific injury location or diagnosis.
Tuesday, February 1, 2011
New 10-Year Study Confirms Too Many Pitches Strike Out Youth Athletes Early
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For years, sports medicine professionals have talked about youth pitching injuries and the stress the motion causes on developing bones and muscles. In a new, 10-year study published in the February issue of the American Journal of Sports Medicine, researchers showed that participants who pitched more than 100 innings in a year were 3.5 times more likely to be injured.
“The study proved a direct link between innings pitched in youth and adolescent baseball and serious pitching injuries. It highlights the need for parents and coaches to monitor the amount of pitching for the long-term success and health of these young athletes. We need to all work together to end the epidemic of youth sports injuries, and education through campaigns like STOP Sports Injuries is in excellent first step,” said lead researcher, Glenn S. Fleisig, PhD, of the American Sports Medicine Institute in Birmingham, Alabama.
The study followed 481 pitchers for 10-years (1999-2008). All were healthy, active youth (aged 9 to 14 years) baseball pitchers at the beginning of the study. Every year each participant was asked whether he played baseball in the previous 12 months and if so what positions, how many innings pitched, what types of pitches he threw, for what teams (spring, summer, fall, winter), and if he participated in baseball showcases. Each player was also asked every year if he had an elbow or shoulder injury that led to surgery or retirement from baseball.
During the 10-year span, five percent of the pitchers suffered a serious injury resulting in surgery or retirement. Two of the boys in the study had surgery before their 13th birthday. Only 2.2 percent were still pitching by the 10th year of the study.
“It is a tough balancing act for adults to give their young athletes as much opportunity as possible to develop skills and strength without exposing them to increased risk of overuse injury. Based on this study, we recommend that pitchers in high school and younger pitch no more than 100 innings in competition in any calendar year. Some pitchers need to be limited even more, as no pitcher should continue to pitch when fatigued,” said Fleisig.
The study also looked at the trend of playing pitcher and catcher in the same game, which did appear to double or triple a player’s risk of injury but the trend was not statistically significant. The study also could not determine if starting curveballs before age 13 increases the risk of injury.
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For years, sports medicine professionals have talked about youth pitching injuries and the stress the motion causes on developing bones and muscles. In a new, 10-year study published in the February issue of the American Journal of Sports Medicine, researchers showed that participants who pitched more than 100 innings in a year were 3.5 times more likely to be injured.
“The study proved a direct link between innings pitched in youth and adolescent baseball and serious pitching injuries. It highlights the need for parents and coaches to monitor the amount of pitching for the long-term success and health of these young athletes. We need to all work together to end the epidemic of youth sports injuries, and education through campaigns like STOP Sports Injuries is in excellent first step,” said lead researcher, Glenn S. Fleisig, PhD, of the American Sports Medicine Institute in Birmingham, Alabama.
The study followed 481 pitchers for 10-years (1999-2008). All were healthy, active youth (aged 9 to 14 years) baseball pitchers at the beginning of the study. Every year each participant was asked whether he played baseball in the previous 12 months and if so what positions, how many innings pitched, what types of pitches he threw, for what teams (spring, summer, fall, winter), and if he participated in baseball showcases. Each player was also asked every year if he had an elbow or shoulder injury that led to surgery or retirement from baseball.
During the 10-year span, five percent of the pitchers suffered a serious injury resulting in surgery or retirement. Two of the boys in the study had surgery before their 13th birthday. Only 2.2 percent were still pitching by the 10th year of the study.
“It is a tough balancing act for adults to give their young athletes as much opportunity as possible to develop skills and strength without exposing them to increased risk of overuse injury. Based on this study, we recommend that pitchers in high school and younger pitch no more than 100 innings in competition in any calendar year. Some pitchers need to be limited even more, as no pitcher should continue to pitch when fatigued,” said Fleisig.
The study also looked at the trend of playing pitcher and catcher in the same game, which did appear to double or triple a player’s risk of injury but the trend was not statistically significant. The study also could not determine if starting curveballs before age 13 increases the risk of injury.
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Thursday, September 2, 2010
Carlos '97 free kick no fluke, say French physicists
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Roberto Carlos' free kick goal against France in 1997's Tournoi de France is thought by many to have been the most skilful free kick goal - from 35m with a powerful curling banana trajectory - ever scored; but by others to have been an incredible fluke.
Taken in 1997, a year before the French won the World Cup, Brazilian Carlos's goal held France to a frustrating draw but, now, a group of French physicists – perhaps with a nostalgic eye to a happier time for French football – have computed the trajectory and shown that Carlos' goal was no fluke.
The research published today, Thursday 2 September, in New Journal of Physics (co-owned by the Institute of Physics and German Physical Society), explains why French goalkeeper Fabien Barthez made no move for the ball (but why a ball-boy ten metres from the goal did duck to safety) as the ball made a last moment sweep left and landed in the back of the net.
Using tiny plastic (polypropylene and polyacetal) balls and a slingshot, the French research team from the École Polytechnique in Palaiseau varied the velocity and spin of balls travelling through water to trace different trajectories.
While their research quickly confirmed the long-known Magnus effect, which gives a spinning ball a curved trajectory, their research revealed fresh insight for spinning balls that are shot over a distance equivalent to Roberto Carlos' free kick.
The friction exerted on a ball by its surrounding atmosphere slows it down enough for the spin to take on a greater role in directing the ball's trajectory, thereby allowing the last moment change in direction, which in the case of Carlos' kick left Barthez defenceless.
The researchers refer to their discovery as the 'spinning ball spiral', comparing the spiraling effects of Roberto Carlos's kick with the shorter-distance (20-25m) 'circular' free kicks shot by the likes of Beckham and Platini.
As Christophe Clanet and David Quéré, researchers from École Polytechnique, write, "When shot from a large enough distance, and with enough power to keep an appreciable velocity as approaching the goal, the ball can have an unexpected trajectory. Carlos' kick started with a classical circular trajectory but suddenly bent in a spectacular way and came back to the goal, although it looked out of the target a small moment earlier.
"People often noticed that Carlos' free kick had been shot from a remarkably long distance; we show in our paper that this is not a coincidence, but a necessary condition for generating a spiral trajectory."
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Roberto Carlos' free kick goal against France in 1997's Tournoi de France is thought by many to have been the most skilful free kick goal - from 35m with a powerful curling banana trajectory - ever scored; but by others to have been an incredible fluke.
Taken in 1997, a year before the French won the World Cup, Brazilian Carlos's goal held France to a frustrating draw but, now, a group of French physicists – perhaps with a nostalgic eye to a happier time for French football – have computed the trajectory and shown that Carlos' goal was no fluke.
The research published today, Thursday 2 September, in New Journal of Physics (co-owned by the Institute of Physics and German Physical Society), explains why French goalkeeper Fabien Barthez made no move for the ball (but why a ball-boy ten metres from the goal did duck to safety) as the ball made a last moment sweep left and landed in the back of the net.
Using tiny plastic (polypropylene and polyacetal) balls and a slingshot, the French research team from the École Polytechnique in Palaiseau varied the velocity and spin of balls travelling through water to trace different trajectories.
While their research quickly confirmed the long-known Magnus effect, which gives a spinning ball a curved trajectory, their research revealed fresh insight for spinning balls that are shot over a distance equivalent to Roberto Carlos' free kick.
The friction exerted on a ball by its surrounding atmosphere slows it down enough for the spin to take on a greater role in directing the ball's trajectory, thereby allowing the last moment change in direction, which in the case of Carlos' kick left Barthez defenceless.
The researchers refer to their discovery as the 'spinning ball spiral', comparing the spiraling effects of Roberto Carlos's kick with the shorter-distance (20-25m) 'circular' free kicks shot by the likes of Beckham and Platini.
As Christophe Clanet and David Quéré, researchers from École Polytechnique, write, "When shot from a large enough distance, and with enough power to keep an appreciable velocity as approaching the goal, the ball can have an unexpected trajectory. Carlos' kick started with a classical circular trajectory but suddenly bent in a spectacular way and came back to the goal, although it looked out of the target a small moment earlier.
"People often noticed that Carlos' free kick had been shot from a remarkably long distance; we show in our paper that this is not a coincidence, but a necessary condition for generating a spiral trajectory."
Ω
Wednesday, September 1, 2010
Men and women use different leg and hip muscles during soccer kick
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Significant differences in knee alignment and muscle activation exist between men and women while kicking a soccer ball, according to a study published this month in the Journal of Bone and Joint Surgery. Data reveals that males activate certain hip and leg muscles more than females during the motion of the instep and side-foot kicks – the most common soccer kicks – which may help explain why female players are more than twice as likely as males to sustain an Anterior Cruciate Ligament (ACL) injury.
Soccer is one of the fastest-growing sports in the United States with approximately 20 million registered players and an annual participation increase of more than 20 percent , according to statistics from the National Collegiate Athletic Association (NCAA) . Women also are playing this sport on more competitive levels. Prior research shows that females are more prone to non-contact ACL injuries than males and though many theories exist, a direct cause for the disparity is unknown.
"By analyzing the detailed motion of a soccer kick in progress, our goal was to home in on some of the differences between the sexes and how they may relate to injury risk," said orthopaedic surgeon Robert H. Brophy, MD, study author and assistant professor of orthopedics, Washington University School of Medicine in St. Louis. "This study offers more information to help us better understand the differences between male and female athletes, particularly soccer players."
Dr. Brophy and his colleagues from the Motion Analysis Laboratory and Sports Medicine Service at the Hospital for Special Surgery in New York used 3-D video-based motion analysis and electromyography to examine the differences between 13 male and 12 female college soccer players during the action of kicking a soccer ball.
Using eight to 10 video cameras, 21 retroreflective markers and 16 electrodes simultaneously, researchers measured the activation of seven muscles (iliacus, gluteus maximus, gluteus medius, vastus lateralis, vastus medialis, hamstrings and gastrocnemius) in both the kicking and supporting legs; as well as two additional muscles (hip adductors and tibialis anterior) in the kicking leg only. Five instep and five side-foot kicks were recorded for each player. Muscle activation was recorded as a percentage of maximum voluntary isometric contraction.
They found that male players activate the hip flexors (inside of the hip) in their kicking leg and the hip abductors (outside of the hip) in their supporting leg more than females.
In the kicking leg, men generated almost four times as much hip flexor activation as females (123 percent in males compared to 34 percent in females).
In the supporting leg, males generated more than twice as much gluteus medius activation (124 percent in males compared with 55 percent in females) and vastus medialis activation (139 percent in males compared with 69 percent in females).
"Activation of the hip abductors may help protect players against ACL injury," said Dr. Brophy, a former collegiate and professional soccer player and past head team physician for the former St. Louis Athletica professional women's soccer club. "Since females have less activation of the hip abductors, their hips tend to collapse into adduction during the kick, which can increase the load on the knee joint in the supporting leg, and potentially put it at greater risk for injury."
Brophy said that although the study does not establish a direct cause-and-effect relationship between muscle activation and knee alignment and ACL injuries, the data "moves us toward better understanding of what may contribute to differences in injury risk between the sexes and what steps we might take to offset this increased risk in females."
The current research in the area of ACL injury prevention has shown some promise. For example, in 2008, the Centers for Disease Control and Prevention published a study that found a new training program called the Prevent Injury and Enhance Performance (PEP) program, was effective in reducing ACL injuries in female soccer players. Developed by the Santa Monica Orthopedic and Sports Medicine Research Foundation and supported by the American Academy of Orthopaedic Surgeons (AAOS) among other medical and athletic associations, PEP is an alternative warm-up regimen that focuses on stretching, strengthening and improving balance and movements and can be conducted during regular practice time and without special equipment.
"Programs focusing on strengthening and recruiting muscles around the hip may be an important part of programs designed to reduce a female athletes' risk of ACL injury," said Dr. Brophy. "Coaches and trainers at all levels, from grade school through professional, should consider using strategies that demonstrate potential to prevent these injuries."
He said that additional research is warranted to investigate how the differences in hip muscle activation and alignment between the sexes may relate to differences in the risk of lower extremity injury among athletes in soccer and other sports.
Significant differences in knee alignment and muscle activation exist between men and women while kicking a soccer ball, according to a study published this month in the Journal of Bone and Joint Surgery. Data reveals that males activate certain hip and leg muscles more than females during the motion of the instep and side-foot kicks – the most common soccer kicks – which may help explain why female players are more than twice as likely as males to sustain an Anterior Cruciate Ligament (ACL) injury.
Soccer is one of the fastest-growing sports in the United States with approximately 20 million registered players and an annual participation increase of more than 20 percent , according to statistics from the National Collegiate Athletic Association (NCAA) . Women also are playing this sport on more competitive levels. Prior research shows that females are more prone to non-contact ACL injuries than males and though many theories exist, a direct cause for the disparity is unknown.
"By analyzing the detailed motion of a soccer kick in progress, our goal was to home in on some of the differences between the sexes and how they may relate to injury risk," said orthopaedic surgeon Robert H. Brophy, MD, study author and assistant professor of orthopedics, Washington University School of Medicine in St. Louis. "This study offers more information to help us better understand the differences between male and female athletes, particularly soccer players."
Dr. Brophy and his colleagues from the Motion Analysis Laboratory and Sports Medicine Service at the Hospital for Special Surgery in New York used 3-D video-based motion analysis and electromyography to examine the differences between 13 male and 12 female college soccer players during the action of kicking a soccer ball.
Using eight to 10 video cameras, 21 retroreflective markers and 16 electrodes simultaneously, researchers measured the activation of seven muscles (iliacus, gluteus maximus, gluteus medius, vastus lateralis, vastus medialis, hamstrings and gastrocnemius) in both the kicking and supporting legs; as well as two additional muscles (hip adductors and tibialis anterior) in the kicking leg only. Five instep and five side-foot kicks were recorded for each player. Muscle activation was recorded as a percentage of maximum voluntary isometric contraction.
They found that male players activate the hip flexors (inside of the hip) in their kicking leg and the hip abductors (outside of the hip) in their supporting leg more than females.
In the kicking leg, men generated almost four times as much hip flexor activation as females (123 percent in males compared to 34 percent in females).
In the supporting leg, males generated more than twice as much gluteus medius activation (124 percent in males compared with 55 percent in females) and vastus medialis activation (139 percent in males compared with 69 percent in females).
"Activation of the hip abductors may help protect players against ACL injury," said Dr. Brophy, a former collegiate and professional soccer player and past head team physician for the former St. Louis Athletica professional women's soccer club. "Since females have less activation of the hip abductors, their hips tend to collapse into adduction during the kick, which can increase the load on the knee joint in the supporting leg, and potentially put it at greater risk for injury."
Brophy said that although the study does not establish a direct cause-and-effect relationship between muscle activation and knee alignment and ACL injuries, the data "moves us toward better understanding of what may contribute to differences in injury risk between the sexes and what steps we might take to offset this increased risk in females."
The current research in the area of ACL injury prevention has shown some promise. For example, in 2008, the Centers for Disease Control and Prevention published a study that found a new training program called the Prevent Injury and Enhance Performance (PEP) program, was effective in reducing ACL injuries in female soccer players. Developed by the Santa Monica Orthopedic and Sports Medicine Research Foundation and supported by the American Academy of Orthopaedic Surgeons (AAOS) among other medical and athletic associations, PEP is an alternative warm-up regimen that focuses on stretching, strengthening and improving balance and movements and can be conducted during regular practice time and without special equipment.
"Programs focusing on strengthening and recruiting muscles around the hip may be an important part of programs designed to reduce a female athletes' risk of ACL injury," said Dr. Brophy. "Coaches and trainers at all levels, from grade school through professional, should consider using strategies that demonstrate potential to prevent these injuries."
He said that additional research is warranted to investigate how the differences in hip muscle activation and alignment between the sexes may relate to differences in the risk of lower extremity injury among athletes in soccer and other sports.
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