Archive for the ‘Cheerleading’ Category

Although it’s too soon to recommend dropping by Starbucks before hitting the gym, a new study suggests that caffeine can help reduce the post-workout soreness that discourages some people from exercising.In a study to be published in the February issue of The Journal of Pain, a team of University of Georgia researchers finds that moderate doses of caffeine, roughly equivalent to two cups of coffee, cut post-workout muscle pain by up to 48 percent in a small sample of volunteers.

Lead author Victor Maridakis, a researcher in the department of kinesiology at the UGA College of Education, said the findings may be particularly relevant to people new to exercise, since they tend to experience the most soreness.

“If you can use caffeine to reduce the pain, it may make it easier to transition from that first week into a much longer exercise program,” he said.

Maridakis and his colleagues studied nine female college students who were not regular caffeine users and did not engage in regular resistance training. One and two days after an exercise session that caused moderate muscle soreness, the volunteers took either caffeine or a placebo and performed two different quadriceps (thigh) exercises, one designed to produce a maximal force, the other designed to generate a sub-maximal force. Those that consumed caffeine one-hour before the maximum force test had a 48 percent reduction in pain compared to the placebo group, while those that took caffeine before the sub-maximal test reported a 26 percent reduction in pain.

Caffeine has long been known to increase alertness and endurance, and a 2003 study led by UGA professor Patrick O’Connor found that caffeine reduces thigh pain during moderate-intensity cycling. O’Connor, who along with professors Kevin McCully and the late Gary Dudley co-authored the current study, explained that caffeine likely works by blocking the body’s receptors for adenosine, a chemical released in response to inflammation.

Despite the positive findings in the study, the researchers say there are some caveats. First, the results may not be applicable to regular caffeine users, since they may be less sensitive to caffeine’s effect. The researchers chose to study women to get a definitive answer in at least one sex, but men may respond differently to caffeine. And the small sample size of nine volunteers means that the study will have to be replicated with a larger study.

O’Connor said that despite these limitations, caffeine appears to be more effective in relieving post-workout muscle pain than several commonly used drugs. Previous studies have found that the pain reliever naproxen (the active ingredient in Aleve) produced a 30 percent reduction in soreness. Aspirin produced a 25 percent reduction, and ibuprofen has produced inconsistent results.

“A lot of times what people use for muscle pain is aspirin or ibuprofen, but caffeine seems to work better than those drugs, at least among women whose daily caffeine consumption is low,” O’Connor said.

Still, the researchers recommend that people use caution when using caffeine before a workout. For some people, too much caffeine can produce side effects such as jitteriness, heart palpitations and sleep disturbances.

“It can reduce pain,” Maridakis said, “but you have to apply some common sense and not go overboard.”

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Article adapted by MD Only Sports Weblog from original press release.
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Contact: Sam Fahmy
University of Georgia

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.

Female athletes often lose their menstrual cycle when training strenuously, but researchers have long speculated on whether this infertility was due to low body fat, low weight or exercise itself. Now, researchers have shown that the cause of athletic amenorrhea is more likely a negative energy balance caused by increasing exercise without increasing food intake.”A growing proportion of women are susceptible to losing their menstrual cycle when exercising strenuously,” says Dr. Nancy I. Williams, assistant professor of kineseology and physiology at Penn State. “If women go six to 12 months without having a menstrual cycle, they could show bone loss. Bone densities in some long distance runners who have gone for a prolonged time period without having normal menstrual cycles can be very low.”

In studies done with monkeys, which show menstrual cyclicity much like women, researchers showed that low energy availability associated with strenuous exercise training plays an important role in causing exercise-induced amenorrhea. These researchers, working at the University of Pittsburgh, published findings in the Journal of Clinical Endocrinology and Metabolism showing that exercise-induced amenorrhea was reversible in the monkeys by increasing food intake while the monkeys still exercised.

Williams worked with Judy L. Cameron, associate professor of psychiatry and cell biology and physiology at the University of Pittsburgh. Dana L. Helmreich and David B. Parfitt, then graduate students, and Anne Caston-Balderrama, at that time a post-doctoral fellow at the University of Pittsburgh, were also part of the research team. The researchers decided to look at an animal model to understand the causes of exercise-induced amenorrhea because it is difficult to closely control factors, such as eating habits and exercise, when studying humans. They chose cynomolgus monkeys because, like humans, they have a menstrual cycle of 28 days, ovulate in mid-cycle and show monthly periods of menses.

“It is difficult to obtain rigorous control in human studies, short of locking people up,” says Williams.

Previous cross-sectional studies and short-term studies in humans had shown a correlation between changes in energy availability and changes in the menstrual cycle, but those studies were not definitive.

There was also some indication that metabolic states experienced by strenuously exercising women were similar to those in chronically calorie restricted people. However, whether the increased energy utilization which occurs with exercise or some other effect of exercise caused exercise-induced reproductive dysfunction was unknown.

“The idea that exercise or something about exercise is harmful to females was not definitively ruled out,” says Williams. “That exercise itself is harmful would be a dangerous message to put out there. We needed to look at what it was about exercise that caused amenorrhea, what it was that suppresses ovulation. To do that, we needed a carefully controlled study.”

After the researchers monitored normal menstrual cycles in eight monkeys for a few months, they trained the monkeys to run on treadmills, slowly increasing their daily training schedule to about six miles per day. Throughout the training period the amount of food provided remained the standard amount for a normal 4.5 to 7.5 pound monkey, although the researchers note that some monkeys did not finish all of their food all of the time.

The researchers found that during the study “there were no significant changes in body weight or caloric intake over the course of training and the development of amenorrhea.” While body weight did not change, there were indications of an adaptation in energy expenditure. That is, the monkeys’ metabolic hormones also changed, with a 20 percent drop in circulating thyroid hormone, suggesting that the suppression of ovulation is more closely related to negative energy balance than to a decrease in body weight.

To seal the conclusion that a negative energy balance was the key to exercise-induced amenorrhea, the researchers took four of the previous eight monkeys and, while keeping them on the same exercise program, provided them with more food than they were used to. All the monkeys eventually resumed normal menstrual cycles. However, those monkeys who increased their food consumption most rapidly and consumed the most additional food, resumed ovulation within as little as 12 to 16 days while those who increased their caloric intake more slowly, took almost two months to resume ovulation.

Williams is now conducting studies on women who agree to exercise and eat according to a prescribed regimen for four to six months. She is concerned because recreational exercisers have the first signs of ovulatory suppression and may easily be thrust into amenorrhea if energy availability declines. Many women that exercise also restrict their calories, consciously or unconsciously.

“Our goal is to test whether practical guidelines can be developed regarding the optimal balance between calories of food taken in and calories expended through exercise in order to maintain ovulation and regular menstrual cycles,” says Williams. “This would then ensure that estrogen levels were also maintained at healthy levels. This is important because estrogen is a key hormone in the body for many physiological systems, influencing bone strength and cardiovascular health, not just reproduction.”

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Article adapted by MD Only Sports Weblog from original press release.
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Contact: A’ndrea Elyse Messer
Penn State

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.

American consumers have long been skeptical about weight-loss supplements, and rightly so. With dozens of nutrients, herbs, and food extracts being marketed as aids for weight loss, there is shockingly little reliable information available concerning the safety and efficacy of any given product. What is more, many so-called miracle pills and quick fixes fail to deliver on the grand weight-loss promises they make, others come with unpleasant side effects, and some have even proven to be dangerous when used incorrectly.

According to Georgetown medical professor Harry Preuss, MD, MACN, CNS, however, there are a number of non-drug weight-loss aids available that do work and can help people shed pounds, build muscle, and burn fat. Based on his own research as well as hundreds of previously recorded scientific studies conducted at major universities and published in leading medical journals, in Dr. Preuss’s new book new book with Bill Gottlieb, THE NATURAL FAT-LOSS PHARMACY (Broadway Books, January 2007), he helps consumers separate the good from the bad and the helpful from the hype and lists the safe, effective, and natural weight-loss supplements on the market.

* HCA (hydroxycitric acid): An extract from the rind of the tamarind fruit, HCA interferes with an enzyme that triggers the formation of fatty acids, cholesterol and triglycerides. It helps lower blood levels of leptin (the substance that triggers hunger), increases serotonin and fat oxidation, and increases production of glycogen, leading to a filling of “fullness.” Study participants taking HCA ate up to 30% less food at every meal.

* MCT (medium chain triglycerides): This class of fatty saturated acids found naturally in coconut and butter help the body burn more calories – up to 25-30% more. The supplement leads to a drop in LDL (bad) cholesterol and reduction in body fat.

* Green and oolong tea extract: One of the antioxidants in green tea is EGCG, which beside possibly preventing cancer, high blood pressure, and diabetes, can also cut down on the creation of body fat and help destroy it through increased oxidation. Studies show that supplements containing EGCG increase calorie-burning by up to 180 calories a day.

* CLA (conjugated linolenic acid): In a study reported in the June 2004 issue of the American Journal of Clinical Nutrition, 180 healthy, overweight men and women were given either CLA or a placebo for one year. On average the CLA group lost 5 pounds of fat and gained 2 pounds of firming muscle – without diet or exercise.

* Chromium: Twenty-five years of research shows that taking supplements of this “trace mineral” can improve the insulin system, which regulates blood sugar levels. With enough chromium, muscle cells can make muscle, there’s less extra sugar to be stored as fat, and excess fat can be burned as fuel. In a study, women who took chromium lost 84% of their weight as fat, while women not taking the supplements lost 92% of their weight as muscle.

* Starch blockers (bean, wheat, hibiscus) and sugar blocker (L-arabinose): Many scientists now agree that cutting down on refined carbohydrates can not only help you get and stay trim, but also help you avoid diabetes, stroke, heart disease, and cancer. It may even slow the aging process. But low-carbohydrate diets are only one option. A smart alternative: carb-blockers made from a bean or wheat or hibiscus flower extract, which block the absorption of refined carbs in the digestive tract if taken before or during a high-carb meal, like pasta or pizza. L-arabinose, a simple sugar found in foods like corn, works to block the absorption of sucrose, meaning you can have your cake and lose the carbohydratess and calories.

* Chitosan and other soluble fibers: In an effort to clean up oil spills, scientists discovered chitosan, a pulverized powder made from the shells of shrimp and crab. This ultra-absorbent powder soaks up oil, grease, and heavy metals, both in the oceans and in the intestinal track. In 1995 Italian researchers gave either chitosan or a placebo to 150 people, who were on a 1,000-calorie-a-day diet for 4 weeks. Those on the placebo lost 4% of their weight, while those on chitosan lost 13%. Other studies show that chitosan can lower cholesterol by 29%. Psyllium, pectin, and guar gum are other soluble fibers that work similarly.

* 5-HTP (5-Hydroxyl-L-tryptophan): Due to high-stress, many people in America have low levels of serotonin, a brain chemical that controls appetite and mood. The result: overeating. 5-HTP is a natural amino acid that boosts serotonin, helping decrease food cravings and also creating a calm state of mind that is less vulnerable to emotional overeating. In an Italian study, overweight women who took serotonin spontaneously began to cut their calories – by more than 1000 calories per day.

* Cacti (Hoodia and Caralluma): The bushmen of the Kalahari desert rely on Hoodia, a form of cactus, to relieve hunger and thirst pangs. Caralluma is an edible Indian cactus that is used in chutneys and pickles and to control appetite, particularly in times of famine. As with Hoodia, scientists speculate that unique molecules in Caralluma affect the hypothalamus, switching off appetite. It can also normalize blood sugar, and after thousands of years of use, there are no known side effects.

* HMB (Hydroxy methylbutyrate): HMB is a metabolite, or a breakdown product of leucine, a component of protein that aids muscle-building. Although found in foods like alfalfa sprouts and catfish, only a supplement can provide enough to protect and build muscle. You do have to exercise to get the benefit of this supplement, but it is especially helpful to those 70 or older as well as AIDS and cancer patients and can lower blood pressure and high cholesterol.

* BCAA (Branched-chain amino acids – leucine, valine, soleucine): Branched chain amino acids comprise 35% of the amino acids in muscle tissue. Supplying muscles with extra BCAA can help prevent exercise-related muscle damage, soreness after exercise, and can build more calorie-burning muscle.

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Article adapted by MD Only Weblog from original press release.
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Contact: Ellen Folan
Random House/Broadway Books

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