Archive for the ‘Basketball’ Category

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.

When it comes to coaching, the pep talk is better than the locker room tirade, University of Florida researchers have found.In a project that applied methods previously used only in classroom settings, a team headed by Professor Robert Singer found that changing people’s attributions, or how they think about themselves, influenced their performance in sports tasks they sought to learn.

“How we think about how we will do and how we’ve just done can very much affect our persistence, our attitudes and our achievements,” said Singer, chair of UF’s department of exercise and sport sciences. “It’s not only a belief in what you can do, it’s also an understanding of thinking more objectively.”

The technique is known as attribution training, which involves using people’s self-perceptions and the extent to which they feel they can control their own behavior to help them succeed at various tasks. Those who believe they can control and change how they feel about themselves are said to have constructive attributions.

In the study, scheduled to be published in March in The Sport Psychologist, Singer and UF colleague Iris Orbach divided 35 college-age beginning tennis players into three groups, each of which was given different instructions regarding personal failure. The first was told they could control their attributions and effort and could change their performance. The second was told their failures were due to a lack of innate ability. The third group was told nothing.

In four trials, the first group scored consistently better in performance, expectation, success perception and emotional control, Singer said. For example, on a test to measure feelings of personal control over behavior, the first group scored twice as high as the control group, while the second group scored below the control group.

In a related study in 1997 that focused on basketball time trials, the first group improved their final time between the first and fourth trials more than twice as much as the control group and more than nine times as much as the second group did.

“When it comes down to it, the primary thing is that you really have to understand what helps you to achieve and what’s under your control,” Singer said. “What has been observed is that those individuals who tend to have more constructive attributions tend to persist longer and tend to achieve more than those who do not have constructive attributions.”

Most studies associated with attribution training techniques have been conducted in the area of education, with the goal of raising the standards for children who are underachievers in the classroom. Singer and Orbach were among the first in the world to apply the techniques to sports.

“Why not try this in a sports setting?” Singer said. “The typical design is to train one group with an attributional orientation that reflects that if you try harder and you try smarter, you’ll have a greater chance of doing well. You’ll learn the skills better and think better things will happen.”

Although it is a common perception that believing in yourself can lead you to success, Singer said his study could have a significant impact on the way people teach and learn athletic activities.

“A lot of times in sports, there’s a negative attitude and a lot of criticism that goes on,” he said. “Probably many athletes and coaches don’t realize the significance of what we’re talking about and the relevance of how people think … I believe that if there’s a better understanding by coaches as to the kind of feedback they give to athletes and how stuff is delivered to them, it could make a difference.”

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Article adapted by MD Only Sports Weblog from original press release.
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Contact: Kristin Harmel
University of Florida

Use of growth hormone to boost athletic performance can lead to diabetes, reports a study published ahead of print in the British Journal of Sports Medicine.

The study reports the case of a 36 year old professional body-builder who required emergency care for chest pain.

He had lost 40 kg in 12 months, during which he had also experienced excessive urination, thirst, and appetite.

He admitted to using anabolic steroids for 15 years and artificial growth hormone for the past three. He had also taken insulin, a year after starting on the growth hormone.

This was done to counter the effects of high blood sugar, but he had stopped taking it after a couple of episodes of acute low blood sugar (hypoglycaemia) while at the gym.

Tests revealed that his liver was inflamed, his kidneys were enlarged and that he had very high blood sugar. He was also dehydrated, and diagnosed with diabetes.

He was given intravenous fluids and gradually increasing amounts of insulin over five days, after which he was discharged. His symptoms completely cleared up, and he was no longer diabetic.

The use of growth hormone has steadily risen among amateur athletes and bodybuilders all round the world, say the authors, because it is easy to buy online and difficult to detect in screening tests—unlike anabolic steroids.

The authors believe that this is the first reported case of diabetes associated with the use of high dose growth hormone, and urge anyone taking high doses to regularly check their blood sugar levels.

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Article adapted by MD Only Sports Weblog from original press release.
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Contact: Emma Dickinson
BMJ Specialty Journals

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.

Active individuals lacking in B-vitamins – including college athletes and other elite competitors — may perform worse during high-intensity exercise and have a decreased ability to repair and build muscle than counterparts with nutrient-rich diets, according to recent Oregon State University research published in the International Journal of Sport Nutrition and Exercise Metabolism.The B-vitamins include thiamin, riboflavin, vitamin B-6, B-12 and folate. These micronutrients are necessary during the body’s process for converting proteins and sugars into energy, and are used during the production and repair of cells, including red blood cells.

For active individuals a marginal deficiency in the nutrients may impact the body’s ability to repair itself, operate efficiently and fight disease, said Melinda Manore, researcher in the Colleges of Agricultural and Health and Human Sciences. Manore analyzed the athletic performance of several elite and collegiate athletes in her research, as well as less competitive individuals.

The stress on the body’s energy producing pathways during exercise, the changes in the body’s tissues resulting from training, an increase in the loss of nutrients in sweat, urine and feces during and after strenuous activity and the additional nutrients needed to repair and maintain higher levels of lean tissue mass present in some athletes and individuals may all affect an individuals B-vitamin requirements, said Manore.

“Many athletes, especially young athletes involved in highly competitive sports, do not realize the impact their diets have on their performance,” said Manore, who is also an Extension Service nutrition scientist. “By the time they reach adulthood they can have seriously jeopardized their abilities and their long-term health.”

Current national B-vitamin recommendations for active individuals may be inadequate, and athletes who follow the recommended daily allowances set by the U.S. government may be receiving lower amounts of nutrients than there bodies need, said Manore. Athletes who restrict calories or limit food groups like dairy or meat have an increased chance of deficiency. Such athletes are often concerned about maintaining a low body weight for sports like gymnastics and wrestling.

“The most vulnerable people are often the individuals society expects to be the healthiest,” said Manore. “There’s a lot of pressure on women in particular to look like an ‘athlete.’ Unfortunately for some people that means skinny and petite, rather than healthy and strong.”

The B-vitamins are in whole and enriched grains, dark green vegetables, nuts, and many animal and dairy products. Manore suggests athletes and individuals with poor or restricted diets consider taking a multivitamin or mineral supplement.

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Article adapted by MD Only Sports Weblog from original press release.
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Contact: Melinda Manore
Oregon State University