Archive for the ‘Marathon’ Category

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

Marathon runners 50 and older, and female athletes in particular, are showing greater improvement in running times than younger runners, according to a study by a Yale professor.Peter Jokl, M.D., professor of orthopedics, and his co-authors, Paul Sethi, M.D., and Andrew Cooper, all of Yale School of Medicine, looked at the running time, age, and gender of all of the runners in the New York City Marathon from 1983 through 1999. They also evaluated the performances of the top 50 male and top 50 female finishers by age categories. There were 415,000 runners in all. Master athletes were classified as those 50 and older.

Jokl said women marathon runners 50-59 improved their average race time by 2.08 minutes per year, which was substantially greater than men runners of the same age, whose running time improved on average about eight seconds per year.

The older male runners, in turn, increased their running time at a much greater rate than younger male runners. The younger runners, male and female ages 20 to 30, did not significantly improve their running times during the period studied. The most significant trends in improved running times noted in the top 50 finishers in the male category occurred in age 60-69 and 70-79, and for women, in ages 50-59 and 60-69.

“Our data reflect the potential for improvement of the general health status of our aging population,” Jokl said. “It is not surprising that the number of participating master athletes continues to rise. There is a general trend towards increasing numbers of our aging population who are in good health and physically able to participate in these types of strenuous competitions.”

He said the performance limits of master athletes appear to be greater than predicted by previous physiologic studies.

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Article adapted by MD Sports Weblog from original press release.
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Contact: Jacqueline Weaver
Yale University

Citation: British Journal of Sports Medicine, Vol. 38: pp 408-412, August 2004

A stunning discovery by German scientists may make blood doping and the treatment of severe anemia as easy as washing your hair.  

In the October print issue of The FASEB Journal (http://www.fasebj.org/), researchers show that the estimated 100,000 hair follicles on each person’s head have the potential to become erythropoietin (EPO) factories. EPO, the hormone primarily responsible for the creation of red blood cells, is used illegally to enhance athletic performance and is used legally to treat severe anemia associated with kidney failure and chemotherapy.

“The ultimate hope is that we’ll be able to up the production of natural EPO in our hair follicles whenever we need it, safely and at a low cost,” said Ralf Paus, senior author of the study. “Our study also highlights that ancient hormones are engaged in many more activities than conventional medical wisdom has assigned to them.”

Normally, EPO is created and released by the kidneys. When the kidneys fail, or when someone undergoes chemotherapy, this process is disrupted and severe anemia occurs. Today, most people are treated using synthetic EPO to bring red blood cells back to normal levels, but synthetic versions of this hormone are relatively expensive. Blood-doping athletes use synthetic EPO to help their bodies bring red blood cells to above-normal levels. This increased concentration of red blood cells allows the blood to deliver more oxygen to muscles than normal, significantly improving endurance and performance. The major danger in boosting the number of red blood cells above normal is that as the blood thickens with red blood cells, the possibility of heart attack increases.

“This study opens doors to an entirely new approach for treating EPO-related anemia,” said Gerald Weissmann, MD, Editor-in-Chief of The FASEB Journal. “The study also is important because it suggests that there is still much to learn about ‘well known’ processes in the body.”

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Article adapted by MD Sports Weblog from original press release.
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Source: Cody Mooneyhan
Federation of American Societies for Experimental Biology

The FASEB Journal (http://www.fasebj.org/) is published by the Federation of American Societies for Experimental Biology (FASEB) and is consistently ranked among the top three biology journals worldwide by the Institute for Scientific Information. FASEB comprises 21 nonprofit societies with more than 80,000 members, making it the largest coalition of biomedical research associations in the United States. FASEB advances biological science through collaborative advocacy for research policies that promote scientific progress and education and lead to improvements in human health.

Don’t drink alcohol. Take vitamins. Avoid eating eggs. We’ve heard these pieces of nutritional advice for years – but are they accurate?

Not necessarily, say two exercise physiologists who presented at the American College of Sports Medicine (ACSM) 11th-annual Health & Fitness Summit & Exposition in Dallas, Texas. Wendy Repovich, Ph.D., FACSM, and Janet Peterson, Dr.P.H., FACSM, set out to debunk the “Top 10 Nutrition Myths.”

According to Repovich and Peterson, these nutrition myths are:

10. Eating carbohydrates makes you fat. Cutting carbs from your diet may have short-term weight loss benefits due to water loss from a decrease in carbohydrate stores, but eating carbs in moderation does not directly lead to weight gain. The body uses carbs for energy, and going too long without them can cause lethargy.

9. Drink eight, 8-oz. glasses of water per day. You should replace water lost through breathing, excrement and sweating each day – but that doesn’t necessarily total 64 ounces of water. It’s hard to measure the exact amount of water you have consumed daily in food and drink, but if your urine is pale yellow, you’re doing a good job. If it’s a darker yellow, drink more H2O.

8. Brown grain products are whole grain products. Brown dyes and additives can give foods the deceiving appearance of whole grain. Read labels to be sure a food is whole grain, and try to get three-ounce equivalents of whole grains per day to reduce the risk of heart disease, diabetes, and stroke.

7. Eating eggs will raise your cholesterol. This myth began because egg yolks have the most concentrated amount of cholesterol of any food. However, there’s not enough cholesterol there to pose health risks if eggs are eaten in moderation. Studies suggest that eating one egg per day will not raise cholesterol levels and that eggs are actually a great source of nutrients.

6. All alcohol is bad for you. Again, moderation is key. Six ounces of wine and 12 ounces of beer are considered moderate amounts, and should not pose any adverse health effects to the average healthy adult. All alcohol is an anticoagulant and red wine also contains antioxidants, so drinking a small amount daily can be beneficial.

5. Vitamin supplements are necessary for everyone. If you eat a variety of fruits, vegetables, and whole grains, along with moderate amounts of a variety of low-fat dairy and protein and the right quantity of calories, you don’t need to supplement. Most Americans do not, so a multi-vitamin might be good. Special vitamin supplements are also recommended for people who are pregnant or have nutritional disorders.

4. Consuming extra protein is necessary to build muscle mass. Contrary to claims of some protein supplement companies, consuming extra protein does nothing to bulk up muscle unless you are also doing significant weight training at the same time. Even then the increased requirement can easily come from food. A potential problem with supplements is the body has to work overtime to get rid of excess protein, and can become distressed as a result.

3. Eating fiber causes problems if you have irritable bowel syndrome (IBS). There are two kinds of fiber: soluble and insoluble. Insoluble fiber can cause problems in IBS sufferers; soluble fiber, however, is more easily absorbed by the body and helps prevent constipation for those with IBS. Soluble fiber is found in most grains.

2. Eating immediately after a workout will improve recovery. Endurance athletes need to take in carbohydrates immediately after a workout to replace glycogen stores, and a small amount of protein with the drink enhances the effect. Drinking low-fat chocolate milk or a carbohydrate drink, like Gatorade, is better for the body, as they replace glycogen stores lost during exercise. Protein is not going to help build muscle, so strength athletes do not need to eat immediately following their workout.

1. Type 2 diabetes can be prevented by eating foods low on the glycemic index. High levels of glucose are not what “cause” diabetes; the disease is caused by the body’s resistance to insulin. Foods high on the glycemic index can cause glucose levels to spike, but this is just an indicator of the presence of diabetes, not the root cause.

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Article adapted by MD Sports Weblog from original press release.
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Contact: Communications and Public Information
American College of Sports Medicine

The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 20,000 International, National and Regional members are dedicated to promoting and integrating scientific research, education and practical applications of sports medicine and exercise science to maintain and enhance physical performance, fitness, health and quality of life.

Drinking water during a long-distance race may do serious harm rather than keep you safe from injury if you’re drinking too much, according to a cardiologist at UT Southwestern Medical Center.Runners or any long-distance athletes who drink too much water during a race could put themselves at jeopardy for developing hyponatremia, a condition marked by a loss in the body’s sodium content that can result in physical symptoms such as lethargy, disorientation, seizures and even respiratory distress.

In a perspectives article in the current issue of The New England Journal of Medicine, Dr. Benjamin Levine, professor of internal medicine at UT Southwestern, said competitive runners are less likely to suffer from hyponatremia.

“Those who are running to finish the race very fast don’t have time to drink a lot of water along the way,” Dr. Levine said. “Those who are not running the race competitively tend to stop at every water station and take a drink. Over the course of a long race, they can dilute themselves.”

In addition popular sports drinks don’t always include enough sodium to offset the body’s loss of the mineral during exercise. The drinks often carry more water with smaller concentrations of salts than are normally found in the human body; therefore, they do not replace salts adequately, said Dr. Levine, medical director of the Institute for Exercise and Environmental Medicine, a collaboration between UT Southwestern and Presbyterian Hospital of Dallas.

The NEJM perspectives article accompanies a study in the same journal by researchers at Children’s Hospital in Boston and Harvard Medical School. The study evaluates the blood concentration of sodium in runners both before and after a long race and examines their risk factors for developing hyponatremia. It recommends individualized fluid-replacement consumption by all competing athletes.

“Researchers of the study found a surprisingly large number of runners had actually gained weight during the race and their sodium concentrations were very low – some were dangerously low,” Dr. Levine said. “The recommendations listed in the study that fluid-replacement schedules be individualized for all athletes competing in long-distance events should be taken seriously by all competitors.”

People lose water and salts from their bodies at different rates during exercise, he said. Heat and humidity also play a role in the rate of this loss. Calculating fluid loss is as simple as weighing yourself before and after exercise and comparing that number to the amount of fluid you consumed throughout.

“All serious distance athletes should find out what their rate of fluid loss is and individualize their fluid intake prior to a distance event,” Dr. Levine said. “It’s also good to accept some mild dehydration during a long race. There are plenty of Web sites available now that show how to customize your fluid intake.”

He also added that taking along salty snacks to eat during the race is a good way of combating hyponatremia. Generally, athletes of all types are instructed prior to activities that water consumption is necessary to prevent illness from heat and to maintain performance levels.

It is also clear, however, that fixed global recommendations for fluid replacement may not be optimal for individual athletes of different body types and with varying degrees of training and heat acclimatization.

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Article adapted by MD Only Sports Weblog from original press release.
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Contact: Katherine Morales
UT Southwestern Medical Center

Peak athletic performance may be related to time of day, suggests a University of Chicago study being presented to the Endocrine Society’s annual meeting, ENDO 2001, in Denver, Colorado, on June 22, 2001. The study shows that the response of the systems regulating energy metabolism and some hormones differs according to when in the day exercise is performed.

Subjects who exercised at night had much larger drops in glucose levels in response to exercise than at other times of day. Exercise in the evening and at night elicited large increases in the levels of two hormones important for energy metabolism, cortisol and thyrotropin. Exercise at other times of day had much smaller effects on these hormones. In contrast, marked increases in growth hormone levels in response to exercise were not effected by the time of day.

“The effects of exercise we observed may explain how some times of day could be better than others for regular exercise or athletic performance, as we might expect from anectdotally reported variations in peak athletic performance,” said Orfeu Buxton, Ph.D., a post-doctoral fellow in endocrinology at the University of Chicago. “We found strong evidence for substantial changes in glucose metabolism and an array of hormonal responses to 1-hour, high-intensity exercise, dependent on the timing of the exercise. Circadian rhythms, generated by our 24-hour internal clock, appear to play an important role in the complex response to exercise.”

For the study, conducted in the Clinical Research Center of the University of Chicago, 40 healthy men, between the ages of 20 and 30, were divided into five groups. Four groups exercised vigorously for one hour on a stair-stepper in the morning, afternoon, evening or night. A control group did not exercise. A standard marker, the timing of melatonin secretion, was used to determine the timing of each individual’s daily rhythm, his circadian “clock time.”

When not exercising, the subjects rested in bed with constant glucose infusion to avoid fluctuation in their blood sugar levels caused by intermittent meals. Blood levels of the “circadian hormones,” melatonin, cortisol and thyrotropin, and the levels of growth hormone and glucose were compared to blood levels for the same time of day in the resting control subjects.

The importance of timing for hormonal secretion and energy metabolism is demonstrated by the distinct 24-hour patterns of secretion for each hormonal system. One hormone may be actively secreted in a complex pulsating pattern while another may be in a resting phase.

Many circadian rhythms, such as heart rate, oxygen consumption, and cardio-pulmonary function play a role in athletic performance. Rhythmic patterns of hormonal secretion provide internal temporal organization essential to the coordination of physiological processes. Physical exercise is associated with marked metabolic changes and can elicit a variety of neuroendocrine responses. Although these metabolic and hormonal responses to morning exercise are well-documented, few studies have examined the effects of exercise at other times of day.

“Our study covers new ground, demonstrating variation in the effects of exercise at four different times of day, with circadian time precisely quantified, with a practical duration of exercise, and with a high intensity designed to elicit maximal effects” said Buxton.

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Article adapted by MD Only Sports Weblog from original press release.
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Contact: Jeanne Galatzer-Levy
University of Chicago Medical Center

Co-authors on the study include, André J. Scheen, M.D., Division of Diabetes, Nutrition and Metabolic Disorders, University of Liége, Belgium; Mireille L’Hermite-Balériaux, Ph.D., Laboratory of Experimental Medicine, Université Libre de Bruxelles, Belgium and Eve Van Cauter, Ph.D., Department of Medicine, University of Chicago.

This work was supported by grants from the Air Force Office of Scientific Research and from the Department of Defense. The University of Chicago Clinical Research Center is supported by a National Institutes of Health grant.

Adolescents who don’t get enough sleep might be jeopardizing their athletic performance, and high school sports teams on the west coast may be at a disadvantage if they play east coast rivals, says Mary Carskadon, PhD, of the Bradley Hasbro Children’s Research Center.Carskadon, a leader in the field of sleep research, compared the results of studies that measured sleep patterns and circadian rhythms in children and adolescents in the May 24 issue of Clinics in Sports Medicine. While it’s widely known that lack of sleep can affect learning, mood and behavior in teenagers, Carskadon suggests that insufficient sleep can also negatively impact teen athletes in a number of ways.

“Young people live in nearly a constant state of chronic insufficient sleep,” says Carskadon, “and adolescents who don’t get enough sleep on a regular basis are extremely impaired in the morning.”

For this reason, she suggests that adolescent travel teams heading westward across time zones have an advantage over home teams early in the day.

While most adults who routinely travel from coast to coast might be well aware of the difficulty adjusting to a different time zone, teens are at even more of a disadvantage.

Evidence suggests that the adolescent circadian rhythm, or internal biological clock, is still adjusting, and their internal day-length is longer than that of adults. This means that teens might not be ready to fall asleep until later in the evening, or may wake up later in the morning.

“For morning games, the home team might still be in the lowest point of alertness,’ while the team that headed west will have the advantage of having been awake for an hour or so longer, and thus have more energy.”

Additionally, if the eastern team arrives the night before, they would gain an extra hour or two of sleep, which can improve focus, alertness, and better reaction skills.

Conversely, she warns that athletic teams taking extended training trips (eg. spring break) of a week or more may experience schedule difficulties on the return home.

“This scenario is most problematic for teams on the east coast that travel west, as student athletes may return with a significant sleep-phase delay that is difficult to correct,” Carskadon says.

Lack of sleep doesn’t just affect athletics in teenagers. Studies repeatedly show that reaction time, vigilance, learning and alertness are impaired by insufficient sleep; so students with short nights and irregular sleep patterns perform poorly in school and in other aspects of their life and have a tendency for a depressed mood.

“Circadian and lifestyle changes conspire to place sleep of adolescents at a markedly delayed time relative to younger children and to adults,” says Carskadon.

In fact, studies have shown that teenagers need as much, if not more sleep as younger children (an average of 9.25 hours per night) but as they mature, their bodies are able to stay alert later into the night.

She cites part-time jobs, caffeinated beverages, social activities, away-games and long practices as factors that help contribute to chronic sleep deprivation for young people.

Is there any reprieve? An afternoon nap can help, but only for so long. Carskadon found that a 45-minute nap taken approximately six hours after waking supported alertness and mood for about eight hours. For a teen who starts his day at 6:30 am, a lunchtime nap could keep him going till 8 or 9 pm.

However, Carskadon warns that afternoon naps don’t help morning fatigue the next day.

“In order to help adolescents do their best, parents need to take an active role in helping set a regular sleep pattern for their teen.”

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Article adapted by MD Only Sports Weblog from original press release.
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Contact: Carol L. Hoy
Lifespan

Mary Carskadon, PhD, directs the Bradley Hospital Sleep and Chronobiology Research Laboratory, and is a Professor of Psychiatry and Human Behavior at Brown Medical School in Providence, RI. She is currently recruiting children and young adults for several studies.

Founded in 1931 as the nation’s first psychiatric hospital for children, Bradley Hospital (www.bradleyhospital.org) remains a premier medical institution devoted exclusively to the research and treatment of childhood psychiatric illnesses. Bradley Hospital, located in Providence, RI, is an affiliate of Brown Medical School and ranks in the top third of private hospitals receiving funding from the National Institutes of Health. Its research arm, the Bradley Hasbro Children’s Research Center (BHCRC), brings together leading researchers in such topics as: autism, colic, childhood sleep patterns, HIV prevention, infant development, obesity, eating disorders, depression, obsessive-compulsive disorder (OCD) and juvenile firesetting. Bradley Hospital is a member of the Lifespan health system.