Archive for the ‘Soccer’ Category

WESTCHESTER, Ill. – Athletes who get an extra amount of sleep are more likely to improve their performance in a game, according to a research abstract presented at the 21st Annual Meeting of the Associated Professional Sleep Societies (APSS).

The study, authored by Cheri Mah of Stanford University, was conducted on six healthy students on the Stanford men’s basketball team, who maintained their typical sleep-wake patterns for a two-week baseline followed by an extended sleep period in which they obtained as much extra sleep as possible. To assess improvements in athletic performance, the students were judged based on their sprint time and shooting percentages.

Significant improvements in athletic performance were observed, including faster sprint time and increased free-throws. Athletes also reported increased energy and improved mood during practices and games, as well as a decreased level of fatigue.

“Although much research has established the detrimental effects of sleep deprivation on cognitive function, mood and performance, relatively little research has investigated the effects of extra sleep over multiple nights on these variables, and even less on the specific relationship between extra sleep and athletic performance. This study illuminated this latter relationship and showed that obtaining extra sleep was associated with improvements in indicators of athletic performance and mood among members of the men’s basketball team.”

The amount of sleep a person gets affects his or her physical health, emotional well-being, mental abilities, productivity and performance. Recent studies associate lack of sleep with serious health problems such as an increased risk of depression, obesity, cardiovascular disease and diabetes.
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Article adapted by MD Sports from original press release.
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Contact: Jim Arcuri
American Academy of Sleep Medicine 

Experts recommend that adults get between seven and eight hours of sleep each night to maintain good health and optimum performance.

Persons who think they might be suffering from a sleep disorder are encouraged to consult with their primary care physician, who will refer them to a sleep specialist.

The annual SLEEP meeting brings together an international body of 5,000 leading researchers and clinicians in the field of sleep medicine to present and discuss new findings and medical developments related to sleep and sleep disorders.

More than 1,000 research abstracts will be presented at the SLEEP meeting, a joint venture of the American Academy of Sleep Medicine and the Sleep Research Society. The four-day scientific meeting will bring to light new findings that enhance the understanding of the processes of sleep and aid the diagnosis and treatment of sleep disorders such as insomnia, narcolepsy and sleep apnea.

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University Park, Pa. — Girls and boys are now equally caught up in the social pressure for a muscular body image currently lauded in popular culture. A Penn State researcher contends those pressures are leading girls and boys down unhealthy avenues such as the misuse of anabolic steroids.

“Young girls have always had to struggle against the media stereotypes of stick-thin models or voluptuous sexuality, but with the rising popularity of women sports, girls are bombarded with buffed body images,” says Dr. Charles Yesalis, professor of health policy and administration, and exercise and sports science at Penn State, and editor of the newest edition of the book “Anabolic Steroids in Sports and Exercise.” “Now, young boys face pop culture musclemen like The Rock and Steve Austin, given the influence of professional wrestling shows.”

“The current film ‘Charlie’s Angels’ sports karate-kicking women in cool clothes,” he added. “Today’s children look with envy at the physiques of actors Arnold Schwarzenegger, Jean-Claude Van Damme, Wesley Snipes, and Linda Hamilton, whose roles call for a muscular build. Hollywood stars are openly taking Human Growth Hormone (HGH) injections to combat aging.”

In addition, children are entering competitive sports at younger ages and many working families have children signed up in two or three sports. Parents, coaches and young athletes are facing growing violence in amateur athletics. The pressure to win at all costs continues to weigh heavily on children, Yesalis notes.

The concern is that many youths will take shortcuts to achieving a muscular build by using anabolic steroids. Female athletes also are pressured to achieve low body fat to excel in their sport. The Penn State researcher has seen evidence that the pressures are reaching down to young children. For example, the book cites figures from the Monitoring The Future Study, a national-level epidemiological survey conducted annually since 1975. Approximately 50,000 8th, 10th and 12 graders are surveyed each year.

The MTF data shows that during the 1990s, anabolic steroid use among 12 graders –both boys and girls – rose to an all-time high with more than 500,000 adolescents having cycled – an episode of use of 6 to 12 weeks – during their lifetime. And the percentage of girls alone doubled in the same period.

A 1998 study of 965 youngsters at four Massachusetts middle schools found that 2.7 percent admitted to taking illegal steroids for better sports performance. That included some boys and girls as young as 10 years old. “This year’s Olympic doping scandals and the epidemic of anabolic steroids in professional baseball just glorify and justify steroids to impressionable youths,” Yesalis notes. “The use of anabolic steroids has cascaded down from the Olympic, professional and college levels to high schools and junior high schools and now middle schools for athletes and non-athletes alike. ”

“Anabolic steroids are made to order for a female wanting to attain a lean athletic body. While most drug abuse has outcomes that tend to discourage use, females who use anabolic steroids may experience a decrease in body fat, increased muscle size and strength, and enhanced sports performance,” he says.

Girls and boys misusing anabolic steroids may win approval and rewards from parents, coaches and peers, but don’t realize there are long-term negative effects on their health, particularly girls, according to Yesalis. Young girls face potential permanent side effects of male hair growth or baldness, deepening of the voice, the enlargement of the clitoris as well as the known risks of heart and liver diseases.

Published by Human Kinetics, the book incorporates the latest research, experience and insights of 15 experts on the scientific, clinical, historical, legal and other aspects of steroid abuse and drug testing. New information looks at the effects of steroids on health, particularly that of women.

This year, trials of East German doctors, coaches and officials reveal records of systematic doping of young athletes without their own or parents’ knowledge. In 1974, officials’ plan to turn the tiny Communist nation into a superpower in sports included giving performance-enhancing drugs to all competing athletes including children as young as 10 years old. The indictments included 142 former East German athletes who now complain of health problems. In media reports, several female athletes report incidents of miscarriages, liver tumor, gynecological problems and enlarged heart, all showing up decades after the steroid misuse.

“Our society’s current strategy for dealing with the abuse of anabolic steroids in sport primarily involves testing, law enforcement and education,” Yesalis says. “But our efforts to deal with this problem have not been very successful. Unless we deal with the social environment that rewards winning at all costs and an unrealistic physical appearance, we won’t even begin to address the problem.”

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Article adapted by MD Sports Weblog from original press release.
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Contact: Vicki Fong
Penn State

Recipe to recover more quickly from exercise: Finish workout, eat pasta, and wash down with five or six cups of strong coffee.

Glycogen, the muscle’s primary fuel source during exercise, is replenished more rapidly when athletes ingest both carbohydrate and caffeine following exhaustive exercise, new research from the online edition of the Journal of Applied Physiology shows. Athletes who ingested caffeine with carbohydrate had 66% more glycogen in their muscles four hours after finishing intense, glycogen-depleting exercise, compared to when they consumed carbohydrate alone, according to the study, published by The American Physiological Society.

The study, “High rates of muscle glycogen resynthesis after exhaustive exercise when carbohydrate is co-ingested with caffeine,” is by David J. Pedersen, Sarah J. Lessard, Vernon G. Coffey, Emmanuel G. Churchley, Andrew M. Wootton, They Ng, Matthew J. Watt and John A. Hawley. Dr. Pedersen is with the Garvan Institute of Medical Research in Sydney, Australia, Dr. Watt is from St. Vincent’s Institute of Medical Research, Fitzroy, Victoria, Australia. All others are with the Royal Melbourne Institute of Technology University (RMIT) in Bundoora, Victoria, Australia.

A fuller audio interview with Dr. Hawley is available in Episode 11 of the APS podcast, Life Lines, at www.lifelines.tv. The show also includes an interview with Dr. Stanley Schultz, whose physiological discovery of how sugar is transported in the gut led to the development of oral rehydration therapy and sports drinks such as Gatorade and Hi-5.

Caffeine aids carbohydrate uptake  

It is already established that consuming carbohydrate and caffeine prior to and during exercise improves a variety of athletic performances. This is the first study to show that caffeine combined with carbohydrates following exercise can help refuel the muscle faster.

“If you have 66% more fuel for the next day’s training or competition, there is absolutely no question you will go farther or faster,” said Dr. Hawley, the study’s senior author. Caffeine is present in common foods and beverages, including coffee, tea, chocolate and cola drinks.

The study was conducted on seven well-trained endurance cyclists who participated in four sessions. The participants first rode a cycle ergometer until exhaustion, and then consumed a low-carbohydrate dinner before going home. This exercise bout was designed to reduce the athletes’ muscle glycogen stores prior to the experimental trial the next day.

The athletes did not eat again until they returned to the lab the next day for the second session when they again cycled until exhaustion. They then ingested a drink that contained carbohydrate alone or carbohydrate plus caffeine and rested in the laboratory for four hours. During this post-exercise rest time, the researchers took several muscle biopsies and multiple blood samples to measure the amount of glycogen being replenished in the muscle, along with the concentrations of glucose-regulating metabolites and hormones in the blood, including glucose and insulin.

The entire two-session process was repeated 7-10 days later. The only difference was that this time, the athletes drank the beverage that they had not consumed in the previous trial. (That is, if they drank the carbohydrate alone in the first trial, they drank the carbohydrate plus caffeine in the second trial, and vice versa.)

The drinks looked, smelled and tasted the same and both contained the same amount of carbohydrate. Neither the researchers nor the cyclists knew which regimen they were receiving, making it a double-blind, placebo-controlled experiment.

Glucose and insulin levels higher with caffeine ingestion
The researchers found the following:  
  • one hour after exercise, muscle glycogen levels had replenished to the same extent whether or not the athlete had the drink containing carbohydrate and caffeine or carbohydrate only
  • four hours after exercise, the drink containing caffeine resulted in 66% higher glycogen levels compared to the carbohydrate-only drink
  • throughout the four-hour recovery period, the caffeinated drink resulted in higher levels of blood glucose and plasma insulin
  • several signaling proteins believed to play a role in glucose transport into the muscle were elevated to a greater extent after the athletes ingested the carbohydrate-plus-caffeine drink, compared to the carbohydrate-only drink

 Dr. Hawley said it is not yet clear how caffeine aids in facilitating glucose uptake from the blood into the muscles. However, the higher circulating blood glucose and plasma insulin levels were likely to be a factor. In addition, caffeine may increase the activity of several signaling enzymes, including the calcium-dependent protein kinase and protein kinase B (also called Akt), which have roles in muscle glucose uptake during and after exercise.

Lower dose is next step  

In this study, the researchers used a high dose of caffeine to establish that it could help the muscles convert ingested carbohydrates to glycogen more rapidly. However, because caffeine can have potentially negative effects, such as disturbing sleep or causing jitteriness, the next step is to determine whether smaller doses could accomplish the same goal.

Hawley pointed out that the responses to caffeine ingestion vary widely between individuals. Indeed, while several of the athletes in the study said they had a difficult time sleeping the night after the trial in which they ingested caffeine (8 mg per kilogram of body weight, the equivalent of drinking 5-6 cups of strong coffee), several others fell asleep during the recovery period and reported no adverse effects.

Athletes who want to incorporate caffeine into their workouts should experiment during training sessions well in advance of an important competition to find out what works for them.

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Article adapted by MD Sports from original press release.
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Contact: Christine Guilfoy
American Physiological Society

Physiology is the study of how molecules, cells, tissues and organs function to create health or disease. The American Physiological Society (APS) has been an integral part of this scientific discovery process since it was established in 1887.

Concussions are common in young athletes but the underlying changes in brain function that occur have been poorly understood. Now, a University of Pittsburgh School of Medicine study is the first to link changes in brain function directly to the recovery of the athlete. Results of the five-year study, funded by the National Institutes of Health, are published in the August issue of the scientific peer-reviewed journal, Neurosurgery, the official journal of the Congress of Neurological Surgeons.

“We found that abnormal brain activity in children and adolescents on functional MRI (fMRI) was clearly related to their performance on neuropsychological tests of attention and memory and to their report of symptoms such as headaches,” said principal investigator Mark Lovell, Ph.D., asssociate professor in the departments of orthopaedic surgery and neurological surgery at the University of Pittsburgh School of Medicine.

“These results confirm crucial objective information that is commonly obtained by neuropsychological testing to help team doctors and athletic trainers make critical decisions about concussion management and safe return to play,” added Dr. Lovell, who is founding director of the University of Pittsburgh Medical Center (UPMC) Sports Medicine Concussion Program, a clinical service and research program focused on the management of sports-related concussions.

“Our findings have several implications for understanding the recovery process after sports-related concussions,” said study co-author Michael (Micky) Collins, Ph.D., assistant professor in the departments of orthopaedic surgery and neurological surgery at Pitt’s School of Medicine, and assistant director of the UPMC program. “Although the results of this study must be considered preliminary, fMRI represents an important evolving technology that is providing further insight now for safe return-to-play decisions in young athletes and may help shape guidelines in the future.”

The study helps define concussion and recovery for safe return-to-play

According to the Centers for Disease Control and Prevention, between 1.4 and 3.6 million sports and recreation-related concussions occur each year, with the majority happening at the high school level. “An explosion of scientific research over the past decade has taught us more about mild traumatic brain injury or concussion than we have ever known,” noted Dr. Lovell, “including the knowledge that mismanagement of even seemingly mild concussions can lead to serious consequences in young athletes.”

A concussion can occur when an athlete receives a traumatic force to the head or upper body that causes the brain to shake inside of the skull. Injury is defined as a concussion when it causes a change in mental status such as loss of consciousness, amnesia, disorientation, confusion or mental fogginess. The severity, effects and recovery of concussion are difficult to determine because no two concussions are alike, and symptoms are not always straightforward. In recent years, research has shown that until a concussed brain is completely healed, the brain may be vulnerable to further injury, which has led to published studies that have raised public awareness and significantly changed the way sports concussions are managed. Importantly, much of this research has included data that proves the usefulness of objective neuropsychological test data as part of the comprehensive clinical evaluation to determine clinical recovery following concussion. In fact, recent international concussion management guidelines have emphasized player symptoms and neuropsychological test results as “cornerstones” of the injury evaluation and management process.

While neuropsychological testing has become an increasingly useful tool, no published studies have examined the relationship between changes in computerized neuropsychological testing completed in a medical clinic and brain function as measured by fMRI. The lack of studies using fMRI may be due to the fact that studies of this nature are very expensive and equipment necessary to undertake this research is not readily available outside of a handful of academic medical centers. UPMC is one of few such centers with the capability of collecting both neurophysiological (fMRI) and neuropsychological data from injured and clinically managed athletes. fMRI is one of the few brain scanning tools that can show brain activity, not just the anatomy. Traditional brain scanning techniques such as MRI and CT are helpful in viewing changes to the brain anatomy in more severe cases, but cannot identify subtle brain-related changes that are believed to occur on a metabolic rather than an anatomic level. fMRI can determine, through measurement of cerebral blood flow and metabolic changes, which parts of the brain are activated in response to different cognitive activities.

fMRI reveals preliminary evidence and lays ground work for future research

“In our study, using fMRI, we demonstrate that the functioning of a network of brain regions is significantly associated with both the severity of concussion symptoms and time to recover,” said Jamie Pardini, Ph.D., a neuropsychologist on the clinical and research staff of the UPMC concussion program and co-author of the study. The study documented the link between changes in brain activation and clinical recovery in concussed athletes, which was defined as a complete resolution of symptoms and neuropsychological testing results that appeared within expected levels or back to the athlete’s personal baseline. “It is our view that studies establishing a link between brain physiology and neuropsychological testing help demonstrate the utility of neuropsychological testing as a proxy for direct measurement of brain functioning after concussion,” Dr. Pardini added.

The research project involved 28 concussed high school athletes and 13 age-matched controls. The concussed athletes underwent fMRI evaluation within approximately one week of injury and then again when they met criteria for clinical recovery. During their fMRI exams, the athletes were given working memory tasks to complete while the brain’s activity was observed and recorded. As a group, athletes who demonstrated the greatest degree of hyperactivation at the time of their first fMRI scan also demonstrated a more prolonged clinical recovery than did athletes who demonstrated less hyperactivation during their first fMRI scan. “We identified networks of brain regions where changes in functional activation were associated with performance on computerized neuropsychological testing and certain post-concussion symptoms,” reported Dr. Pardini. “Also, our study confirms previous research suggesting that there are neurophysiological abnormalities that can be measured even after a seemingly mild concussion,” she added. The study utilized a computer-based neuropsychological test called ImPACT™ (Immediate Post-Concussion and Cognitive Testing), which measures cognitive function such as attention, memory, speed of response and decision making. ImPACT was developed by Dr. Lovell and colleagues over the past decade and has been extensively researched by the University of Pittsburgh and other academic institutions throughout the world. Drs. Lovell and Collins have a proprietary interest in the ImPACT test as does UPMC. ImPACT Applications, Inc., is a Pittsburgh-based company that owns and licenses the ImPACT tool.

“Recent years have marked exciting and important discoveries in sports concussion research but there are still many unanswered questions,” said Dr. Lovell. “Continued research designed to evaluate multiple parameters of concussion effects and recovery will further help structure return-to-play guidelines.”

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Article adapted by MD Sports Weblog from original press release.
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Contact: Susan Manko
University of Pittsburgh Schools of the Health Sciences

Other authors of the study include James Becker, Ph.D., of the University of Pittsburgh; Joel Welling, Ph.D., Jennifer Bakal and William Eddy, Ph.D., of Carnegie-Mellon University; Nicole Lazar, Ph.D., of the University of Georgia, Athens, Ga.; and Rebecca Roush, Psychology Software Tools, Pittsburgh. The study was funded by a $3 million grant from the National Institutes of Health.

Football players who suffer the dangerous head injury known as concussion are three times more likely than other players to suffer a second concussion in the same season, according to a new University of North Carolina at Chapel Hill study.The study, published in the September-October issue of the American Journal of Sports Medicine, suggests that the brain is more susceptible to injury when it has not had enough time to recover from a first injury. Researchers say the finding is important because concussions can lead to permanent brain damage, vision impairment or even death if not managed properly.

“We believe recurrences are more likely because injured players are returning to practice and to games too quickly after blows to the head,” said Dr. Kevin M. Guskiewicz, assistant professor of exercise and sport science at UNC-CH and study leader. “Many clinicians are not following the medical guidelines that players should be symptom-free for several days before returning.”

Guskiewicz directs the Sports Medicine Research Laboratory and the Undergraduate Athletic Training Education Program, both at UNC-CH. Co-authors of the new paper are Nancy L. Weaver, research associate for the N.C. High School Injury Surveillance Program; Darin A. Padua, doctoral student in sports medicine at the University of Virginia; and Dr. William E. Garrett Jr., professor and chair of orthopaedics at the UNC-CH School of Medicine.

For three years, the researchers surveyed a random sample of 242 certified athletic trainers across the United States who worked with high school and college football teams. More than 17,500 football players were represented in the study, which covered 1995 to 1997. About 5 percent suffered concussions each year. Researchers also conducted telephone interviews with a smaller group.

“We wanted to learn more about concussions — the incidence of injury, the mechanism of injury and whether players seemed to be injured more frequently on artificial turf than on grass,” Guskiewicz said. “We found the incidence of injury to be highest at the high school and Division III level, while Division I and II college players suffered fewer concussive injuries.”

Possible explanations include poorer quality and fit of protective equipment, he said. Another possibility is that college players are more skilled on average, and better players are known to be less susceptible to injury.

The UNC-CH professor and colleagues found that 31 percent of athletes with concussions began playing again the same day they were injured.

“This didn’t surprise us, but it does worry us,” Guskiewicz said. “Eighty-six percent of players reported having at least a headache after the incident, and you should never return to play with a headache. It was probably all right for the 14 percent of players with no symptoms to return.”

Artificial turf didn’t produce more head injuries than natural grass, the researchers found. Concussions on artificial turf, however, were more serious. Artificial athletic fields are sheets of synthetic grass over shock-absorbing pads stretched across concrete slabs.

Another key finding was that only one in 20 players suffered a concussion during the season rather than the one in five reported in 1983. Almost 15 percent of injured players suffered a second concussion in the same season, and it tended to be more serious than the first. The most common symptoms were headache, dizziness and confusion.

“That earlier 20 percent figure appears to have been a gross over-estimation,” Guskiewicz said. “Still, the rules have changed to make the game safer and the equipment, especially helmets, are safer and have to be approved by the National Operating Committee on Standards in Athletic Equipment (NOCSAE). Also, many coaches are being smarter in limiting physical contact time in practices. They are stressing the importance of players keeping their heads up during blocking and tackling, not dropping their heads, which is against the newer rules and is much more dangerous.”

Defensive backs, offensive linemen and linebackers were the most frequently concussed players, but special team players and wide receivers were more likely to suffer more serious concussions. During the 1999 season, all six U.S. high school players killed as a direct result of football accidents died from injuries to their brains, according to a different UNC-CH study released in August.

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Article adapted by MD Sports Weblog from original press release.
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Contact: David Williamson
University of North Carolina at Chapel Hill

Energy bars, touted for improving athletic performance while providing the right combination of essential nutrients, may not always give endurance athletes the boost they expect.An Ohio State University researcher compared two popular energy bars and found that one of the bars didn’t give the moderate increase in blood sugar known to enhance performance in endurance athletes. Instead, its effect was much like a candy bar – giving a big rush of sugar to the blood, followed by a sharp decline.

“Theoretically, energy bars produce more moderate increases and decreases in blood sugar levels than a typical candy bar,” said Steve Hertzler, an associate professor of medical dietetics at Ohio State. “But these claims aren’t necessarily valid.” His study appears in a recent issue of the Journal of the American Dietetic Association.

Hertzler wanted to know how energy bars affected blood glucose levels. Glucose is a sugar that provides energy to the body’s cells – for example, red-blood cells and most parts of the brain derive most of their energy from glucose.

“Athletes – especially those involved in endurance sports – want to enhance performance, and energy bars claim to help keep blood sugar levels at a moderate level,” Hertzler said.

Volunteers had to fast for at least 12 hours before taking part in each of four experiments. Then, they ate one of four experimental “meals” consisting of either four slices of white bread; a Snickers bar; an Ironman PR Bar; or a PowerBar. Each experimental meal provided the same amount of carbohydrates (50 grams.)

Hertzler then tested the effects these foods had on blood glucose levels at 15-minute intervals for up to two hours after each experimental meal. The volunteers had to wait at least 24 hours between each experimental meal.

Hertzler measured each subject’s blood samples for glucose levels, to determine which food most raised blood sugar levels.

Both energy bars caused blood glucose levels to peak at 30 minutes, while levels peaked at 45 minutes after the bread and candy bar were consumed. Blood glucose levels declined steadily throughout the duration of testing for all foods but the Ironman PR Bar. This bar caused blood glucose rates to remain fairly steady, probably because of the moderate carbohydrate level of the bar, according to Hertzler.

“Though blood glucose rates peaked at 30 minutes with both bars, the high-carbohydrate energy bar – the PowerBar – caused a much sharper decline,” Hertzler said. “In fact, the decline was sharper than with the candy bar.” Much of the energy derived from the bread and the candy bar came from carbohydrate and the same was true for the PowerBar. While the bar is low in protein and fat, more than 70 percent of it is made up of carbohydrate (such as high-fructose corn syrup; oat bran; and brown rice). In contrast, 40 percent of the Ironman PR is comprised of carbohydrate (high fructose corn syrup and fructose.) The rest of the bar was comprised of 30 percent fat and 30 percent protein.

“The composition of this bar may have been responsible for the diminished blood glucose response,” Hertzler said. “Athletes involved in short-duration events who want a quick energy boost should eat a high-carbohydrate energy bar or a candy bar,” he suggests. “However, endurance athletes would do well to consume an energy bar with a moderate carbohydrate level.”

Hertzler conducted this study while at Kent State University in Kent, Ohio. He is continuing similar research at Ohio State.

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Article adapted by MD Sports Weblog from original press release.
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Contact: Steve Hertzler
Ohio State University

Editor’s note: This research was funded by a grant from Kent State University. The researcher received no funding from either energy bar manufacturer.

Trained runners who severely limit the amount of fat in their diets may be suppressing their immune system and increasing their susceptibility to infections and inflammation, a University at Buffalo study has shown.In findings presented here today (May 22, 1999) at the fourth International Society for Exercise and Immunology Symposium, lead author Jaya T. Venkatraman, Ph.D., reported that running 40 miles per week on a diet composed of approximately 17 percent fat compromised the runners’ immune response.

The medium and high-fat diets, composed of approximately 32 and 41 percent fat respectively, left the immune system intact, and enhanced certain components, the findings showed.

“The data suggest that higher-fat diets may lower the proinflammatory cytokines, free radicals and hormones, and may enhance the levels of anti-inflammatory cytokines,” Venkatraman said.

Venkatraman is an associate professor of nutrition in the Department of Physical Therapy, Exercise and Nutrition Sciences in the UB School of Health Related Professions.

Earlier studies published by a UB research group headed by David Pendergast, Ed.D., professor of physiology and biophysics, reported that competitive runners who increased the proportion of fat in their diets improved their endurance with no negative effect on weight, body composition, blood pressure, pulse rate or total cholesterol. (See editor’s note)

However, since a high level of fat was thought to be immunosuppressive, the researchers sought to determine if increasing dietary fat would compromise various elements of the immune system, while improving performance.

“In general, moderate levels of exercise are known to enhance the immune system,” said Venkatraman. “But high-intensity exercise and endurance exercise produce excess levels of free radicals, which may place stress on the immune system.

“Since we have shown that athletes perform better on a higher-fat diet than on a low-fat diet, it was important to determine if the higher-fat diet would further compromise the immune system,” she said. “We found that it did not, but the very-low-fat diet did.”

The study involved six female and eight male competitive runners who trained at 40 miles a week and were part of a larger performance study. They spent a month on their normal diets, followed by a month each on diets composed of approximately 17 percent, 32 percent and 41 percent fat. Protein remained stable at 15 percent and carbohydrates made up the difference.

The immune status of the runners was obtained by analyzing concentrations of essential components of the immune system — leukocytes, cytokines and plasma cortisol — in blood samples taken before and after an endurance exercise test. The tests were conducted at the end of each four-week diet period.

Results showed that natural killer cells, a type of leukocyte and one of the body’s defense mechanisms marshaled to fight infection, were more than doubled in runners after the high-fat diet, compared to the low-fat regimen. Levels of PGE2, inflammation-causing prostaglandins, increased after the endurance test and were higher when the runners were on the low-fat diet.

This study is part of a larger investigation to determine the effects of dietary fat on performance, biochemical and nutritional status, and plasma lipids and lipoprotein profiles in distance runners being conducted by a study group composed of — in addition to Venkatraman and Pendergast — Peter Horvath, Ph.D., associate professor in the UB Department of Physical Therapy, Exercise and Nutrition Sciences, and John Leddy, M.D., clinical professor of orthopaedics and associate director of the UB Sports Medicine Institute.

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Article adapted by MD Sports Weblog from original press release.
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Contact: Lois Baker
University at Buffalo