Archive for August, 2008

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.

 —————————-
Article adapted by MD Sports from original press release.
—————————-

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.

A University of Colorado at Boulder study of a space-age, low-gravity training machine used by several 2008 Olympic runners showed it reduced impacts on muscles and joints by nearly half when subjects ran at the equivalent of 50 percent of their body weight.

The new study has implications for both competitive runners rehabilitating from injuries and for ordinary people returning from knee and hip surgeries, according to Associate Professor Rodger Kram of CU-Boulder’s integrative physiology department.

Known as the “G-Trainer,” the machine consists of a treadmill surrounded by an inflatable plastic chamber that encases the lower body of the runner, said Kram. Air pumped into the chamber increases the pressure and effectively reduces the weight of runners, who are sealed in the machine at the waist in a donut-shaped device with a special zipper and “literally lifted up by their padded neoprene shorts,” he said.

Published in the August issue of the Journal of Applied Biomechanics, the study is the first to quantify the effects of running in the G-Trainer, built by Alter-G Inc. of Menlo Park, Calif., using technology developed at NASA’s Ames Research Center in California. The paper was authored by Kram and former CU-Boulder doctoral student Alena Grabowski, now a postdoctoral researcher at the Massachusetts Institute of Technology.

Although G-Trainers have been used in some sports clinics and college and professional sports training rooms since 2006, the new study is the first scientific analysis of the device as a training tool for running, said Grabowski.

“The idea was to measure which levels of weight support and speeds give us the best combination of aerobic workout while reducing the impact on joints,” said Kram. “We showed that a person can run faster in the G-Trainer at a lower weight and still get substantial aerobic benefits while maintaining good neuromuscular coordination.”

The results indicated a subject running at the equivalent of half their weight in the G-Trainer at about 10 feet per second, for example — the equivalent of a seven-minute mile — decreased the “peak” force resulting from heel impact by 44 percent, said Grabowski. That is important, she said, because each foot impact at high speed can jar the body with a force equal to twice a runner’s weight.

Several former CU track athletes participating in the 2008 Olympics in Beijing have used the machine, said Kram. Alumna Kara Goucher, who will be running the 5,000- and 10,000-meter races in Beijing, has used the one in Kram’s CU-Boulder lab and one in Eugene, Ore., for rehabilitation, and former CU All-American and Olympic marathoner Dathan Ritzenhein also uses a G-Trainer in his home in Oregon. Other current CU track athletes who have been injured have tried the machine in Kram’s lab and found it helpful to maintain their fitness as they recovered, Kram said.

For the study, the researchers retrofitted the G-Trainer with a force-measuring treadmill invented by Kram’s team that charts vertical and horizontal stress load on each foot during locomotion, measuring the variation of biomechanical forces on the legs during running. Ten subjects each ran at three different speeds at various reduced weights, with each run lasting seven minutes. The researchers also measured oxygen consumption during each test, Kram said.

Grabowski likened the effect of the G-Trainer on a runner to pressurized air pushing on the cork of a bottle. “If you can decrease the intensity of these peak forces during running, then you probably will decrease the risk of injury to the runner.”

The G-Trainer is a spinoff of technology originally developed by Rob Whalen, who conceived the idea while working at NASA Ames as a National Research Council fellow to help astronauts maintain fitness during prolonged space flight. While the NASA technology was designed to effectively increase the weight of the astronauts to stem muscle atrophy and bone loss in low-gravity conditions, the G-Trainer reverses the process, said Grabowski.

In the past, sports trainers and researchers have used climbing harnesses over treadmills or flotation devices in deep-water swimming pools to help support the weight of subjects, said Kram. Harnesses are cumbersome, while pool exercises don’t provide sufficient aerobic stimulation and biomechanical loading on the legs, he said.

Marathon world-record holder Paula Radcliffe of Great Britain is currently using a G-Trainer in her high-altitude training base in Font-Remeu, France. Radcliffe is trying to stay in top running shape while recovering from a stress fracture in her femur in time for the 2008 Olympic women’s marathon on Aug. 17, according to the London Telegraph.

Kram and Grabowski have begun a follow-up study of walking using the G-Trainer. By studying subjects walking at various weights and speeds in the machine, the researchers should be able to quantify its effectiveness as a rehabilitation device for people recovering from surgeries, stress fractures and other lower body injuries, Kram said.

—————————-
Article adapted by MD Sports from original press release.
—————————-

Contact: Rodger Kram
University of Colorado at Boulder

Neuroscience researchers at the Duke-NUS Graduate Medical School in Singapore have shown for the first time what happens to the visual perceptions of healthy but sleep-deprived volunteers who fight to stay awake, like people who try to drive through the night.

The scientists found that even after sleep deprivation, people had periods of near-normal brain function in which they could finish tasks quickly. However, this normalcy mixed with periods of slow response and severe drops in visual processing and attention, according to their paper, published in the Journal of Neuroscience on May 21.

“Interestingly, the team found that a sleep-deprived brain can normally process simple visuals, like flashing checkerboards. But the ‘higher visual areas’ – those that are responsible for making sense of what we see – didn’t function well,” said Dr. Michael Chee, lead author and professor at the Neurobehavioral Disorders Program at Duke-NUS. “Herein lies the peril of sleep deprivation.”

The research team, including colleagues at the University of Michigan and University of Pennsylvania, used magnetic resonance imaging to measure blood flow in the brain during speedy normal responses and slow “lapse” responses. The study was funded by grants from the DSO National Laboratories in Singapore, the National Institutes of Health, the National Institute on Drug Abuse, the NASA Commercialization Center, and the Air Force Office of Scientific Research.

Study subjects were asked to identify letters flashing briefly in front of them. They saw either a large H or S, and each was made up of smaller Hs or Ss. Sometimes the large letter matched the smaller letters; sometimes they didn’t. Scientists asked the volunteers to identify either the smaller or the larger letters by pushing one of two buttons.

During slow responses, sleep-deprived volunteers had dramatic decreases in their higher visual cortex activity. At the same time, as expected, their frontal and parietal ‘control regions’ were less able to make their usual corrections.

Scientists also could see brief failures in the control regions during the rare lapses that volunteers had after a normal night’s sleep. However, the failures in visual processing were specific only to lapses that occurred during sleep deprivation.

The scientists theorize that this sputtering along of cognition during sleep deprivation shows the competing effects of trying to stay awake while the brain is shutting things down for sleep. The brain ordinarily becomes less responsive to sensory stimuli during sleep, Chee said.

This study has implications for a whole range of people who have to struggle through night work, from truckers to on-call doctors. “The periods of apparently normal functioning could give a false sense of competency and security when in fact, the brain’s inconsistency could have dire consequences,” Chee said.

“The study task appeared simple, but as we showed in previous work, you can’t effectively memorize or process what you see if your brain isn’t capturing that information,” Chee said. “The next step in our work is to see what we might do to improve things, besides just offering coffee, now that we have a better idea where the weak links in the system are.”

 

—————————-
Article adapted by MD Sports from original press release.
—————————-

Contact: Mary Jane Gore
Duke University Medical Center

Other authors of the study include Jiat Chow Tan, Hui Zheng, and Sarayu Parimal of the Cognitive Neuroscience Lab at the Duke-NUS Graduate Medical School; Daniel Weissman of the University of Michigan Psychology Department; David Dinges of the University of Pennsylvania School of Medicine; and Vitali Zagorodnov of the Computer Engineering Department of the Nanyang Technological University in Singapore.

Boosting an exercise-related gene in the brain works as a powerful anti-depressant in mice—a finding that could lead to a new anti-depressant drug target, according to a Yale School of Medicine report in Nature Medicine.

“The VGF exercise-related gene and target for drug development could be even better than chemical antidepressants because it is already present in the brain,” said Ronald Duman, professor of psychiatry and senior author of the study.

Depression affects 16 percent of the population in the United States, at a related cost of $83 billion each year. Currently available anti-depressants help 65 percent of patients and require weeks to months before the patients experience relief.

Duman said it is known that exercise improves brain function and mental health, and provides protective benefits in the event of a brain injury or disease, but how this all happens in the brain is not well understood. He said the fact that existing medications take so long to work indicates that some neuronal adaptation or plasticity is needed.

He and his colleagues designed a custom microarray that was optimized to show small changes in gene expression, particularly in the brain’s hippocampus, a limbic structure highly sensitive to stress hormones, depression, and anti-depressants.

They then compared the brain activity of sedentary mice to those who were given running wheels. The researchers observed that the mice with wheels within one week were running more than six miles each night. Four independent array analyses of the mice turned up 33 hippocampal exercise-regulated genes—27 of which had never been identified before.

The action of one gene in particular—VGF—was greatly enhanced by exercise. Moreover, administering VGF functioned like a powerful anti-depressant, while blocking VGF inhibited the effects of exercise and induced depressive-like behavior in the mice.

“Identification of VGF provides a mechanism by which exercise produces antidepressant effects,” Duman said. “This information further supports the benefits of exercise and provides a novel target for the development of new antidepressants with a completely different mechanism of action than existing medications.”

—————————-
Article adapted by MD Sports Weblog from original press release.
—————————-

Contact: Jacqueline Weaver
Yale University
Nature Medicine

Lower muscle mass and an increase in body fat are common consequences of growing older.

While exercise is a proven way to prevent the loss of muscle mass, a new study led by McMaster researcher Dr. Mark Tarnopolsky shows that taking a combination of creatine monohydrate (CrM) and conjugated linoleic acid (CLA) in addition to resistance exercise training provides even greater benefits.

The study to be published on Oct. 3 in PLoS One, an international, peer-reviewed online journal of the Public Library of Science, involved 19 men and 20 women who were 65 years or older and took part in a six-month program of regular resistance exercise training.

In the randomized double blind trial, some of the participants were given a daily supplement of creatine (a naturally produced compound that supplies energy to muscles) and linoleic acid (a naturally occurring fatty acid), while others were given a placebo. All participants took part in the same exercise program.

The exercise training resulted in improvements of functional ability and strength in all participants, but those taking the CrM and CLA showed even greater gains in muscle endurance, an increase in fat-free mass and a decrease in the percentage of body fat.

“This data confirms that supervised resistance exercise training is safe and effective for increasing strength and function in older adults and that a combination of CrM and CLA can enhance some of the beneficial effects of training over a six month period,” said Tarnopolsky, a professor of pediatrics and medicine.

This study provides functional outcomes that build on an earlier mechanistic study co-led by Tarnopolsky and Dr. S. Melov at the Buck Institute of Age Research, published in PLoS One this year, which provided evidence that six months of resistance exercise reversed some of the muscle gene expression abnormalities associated with the aging process.
—————————-
Article adapted by MD Sports Weblog from original press release.
—————————-

Contact: Veronica McGuire
McMaster University

Trying to reap the health benefits of exercise? Forget treadmills and spin classes, researchers at the Salk Institute for Biological Studies may have found a way around the sweat and pain. They identified two signaling pathways that are activated in response to exercise and converge to dramatically increase endurance.

The team of scientists, led by Howard Hughes Medical Investigator Ronald M. Evans, Ph.D., a professor in the Salk Institute’s Gene Expression Laboratory report in the July 31 advance online edition of the journal Cell that simultaneously triggering both pathways with oral drugs turned laboratory mice into long-distance runners and conferred many of exercise’s other benefits.

In addition to their allure for endurance athletes, drugs that mimic the effects of exercise have therapeutic potential in treating certain muscle diseases, such as wasting and frailty, hospital patients unable to exercise, veterans and others with disabilities as well as obesity and a slew of associated metabolic disorders where exercise is known to be beneficial.

Previous work with genetically engineered mice in the Evans lab had revealed that permanently activating a genetic switch known as PPAR delta turned mice into indefatigable marathon runners. In addition to their super-endurance, the altered mice were resistant to weight gain, even when fed a high-fat diet that caused obesity in ordinary mice. On top of their lean and mean physique, their response to insulin improved, lowering levels of circulating glucose.

“We wanted to know whether a drug specific for PPAR delta would have the same beneficial effects,” says Evans. “Genetic engineering in humans, commonly known as gene doping when mentioned in connection with athletic performance, is certainly feasible but very impractical.”

An investigational drug, identified only as GW1516 (and not commercially available), fit the bill. When postdoctoral researcher and lead author Vihang A. Narkar, Ph.D., fed the substance to laboratory mice over a period of four weeks, the researchers were in for a surprise.

“We got the expected benefits in lowering fatty acids and blood glucose levels but no effect, absolutely none, on exercise performance,” says Narkar. Undeterred, he put mice treated with GW1516 on a regular exercise regimen and every day had them run up to 50 minutes on a treadmill.

Now the exact same drug that had shown no effect in sedentary animals improved endurance by 77 percent over exercise alone and increased the portion of “non-fatiguing” or “slow twitch” muscle fibers by 38 percent. The result, while very dramatic, gave rise to a vexing question: Why is exercise so important?

First and foremost, exercise depletes muscles’ energy store, a chemical known as ATP. In times of high demand, ATP releases all its energy and forms AMP. Rising AMP levels alert AMPK, a metabolic master regulator, which acts like a gas gauge that the cell is running on empty and revs up the production of ATP. “That led us to consider whether AMPK activation was the critical trigger that allowed PPAR delta to work,” recalls Narkar.

Usually, AMPK can be found in the cytoplasm, the compartment that surrounds the nucleus, but the Salk researchers’ experiment revealed that some exercise-activated AMPK molecules slip into the nucleus. There they physically interact with PPAR delta and increase its ability to turn on the genetic network that increases endurance.

“It essentially puts a turbo charge on PPAR delta, which explains why exercise is so important,” says Evans.

Then came the ultimate couch potato experiment. The researchers fed untrained mice AICAR, a synthetic AMP analog that directly activates AMPK. After only four weeks and without any prior training, these mice got up and ran 44 percent longer than untreated, untrained mice. “That’s as much improvement as we get with regular exercise,” says Narkar.

“Exercise in a pill” might sound tempting to couch potatoes and Olympic contenders alike, but the dreams of the latter might be cut short. Evans developed a test that can readily detect GW1516 and its metabolites as well as AICAR in blood and urine and is already working with officials at the World Anti-Doping Association, who are racing to have a test in place in time for this year’s Summer Olympics.

—————————-
Article adapted by MD Sports Weblog from original press release.
—————————-

Contact: Gina Kirchweger
Salk Institute

The study was supported by the Howard Hughes Medical Institute, the Hillblom Foundation and the National Institute of Health.

Researchers who contributed to the work include postdoctoral researchers Michael Downes, Ph.D., Ruth T. Yu, Ph.D., doctoral candidate Emi Embler, B.S., research associates Michael C. Nelson, B.S., Yuhua Zou, M.S., Ester Banayo, and Henry Juguilon, in the Gene Expression Laboratory, doctoral candidate M. Mihaylova, and assistant professor Reuben Shaw, Ph.D., in the Molecular and Cell Biology Laboratory, assistant professor Yong-Xu Wang, Ph.D., at the University of Massachusetts Medical School, Massachusetts, and professor Heonjoon Kang, Ph.D., at the School of Earth and Environmental Sciences, Seoul National University, South Korea.