Archive for the ‘Endurance’ Category

Researchers at The University of Auckland have shown for the first time that the mere presence of carbohydrate solution in the mouth immediately boosts muscle strength, even before it is swallowed.

The results suggest that a previously unknown neural pathway is activated when receptors in the mouth detect carbohydrate, stimulating parts of the brain that control muscle activity and producing an increase in muscle strength.

Previous research had shown that the presence of carbohydrate in the mouth can improve physical performance during prolonged activity, but the mechanism involved was not known and it was unclear whether a person must be fatigued for the effect to be seen.

“There appears to be a pathway in the brain that tells our muscles when energy is on the way,” says lead researcher Dr Nicholas Gant from the Department of Sport and Exercise Science.

“We have shown that carbohydrate in the mouth produces an immediate increase in neural drive to both fresh and fatigued muscle and that the size of the effect is unrelated to the amount of glucose in the blood or the extent of fatigue.”

The current research has been published in the journal Brain Research and has also captured the attention of New Scientist magazine.

In the first of two experiments, 16 healthy young men who had been doing biceps exercises for 11 minutes were given a carbohydrate solution to drink or an identically flavored energy-free placebo. Their biceps strength was measured before and immediately afterward, as was the activity of the brain pathway known to supply the biceps.

Around one second after swallowing the drink, neural activity increased by 30 percent and muscle strength two percent, with the effect lasting for around three minutes. The response was not related to the amount of glucose in the bloodstream or how fatigued the participants were.

“It might not sound like much, but a two percent increase in muscle strength is enormous, especially at the elite level. It’s the difference between winning an Olympic medal or not,” says co-author Dr Cathy Stinear.

As might be expected, a second boost in muscle strength was observed after 10 minutes when carbohydrate reached the bloodstream and muscles through digestion, but no additional boost in neural activity was seen at that time.

“Two quite distinct mechanisms are involved,” says Dr Stinear. “The first is the signal from the mouth via the brain that energy is about to be available and the second is when the carbohydrate actually reaches the muscles and provides that energy,” says Dr Stinear.

“The carbohydrate and placebo solutions used in the experiment were of identical flavor and sweetness, confirming that receptors in the mouth can process other sensory information aside from the basic taste qualities of food. The results suggest that detecting energy may be a sixth taste sense in humans,” says Dr Gant.

In the second experiment, 17 participants who had not been doing exercise and were not fatigued simply held one of the solutions in their mouths without swallowing. Measurements of the muscle between the thumb and index finger were taken while the muscle was either relaxed or active.

A similar, though smaller effect was observed as in the first experiment, with a nine percent increase in neural activity produced by the carbohydrate solution compared with placebo. This showed that the response is seen in both large powerful muscles and in smaller muscles responsible for fine hand movements.

“Together the results show that carbohydrate in the mouth activates the neural pathway whether or not muscles are fatigued. We were surprised by this, because we had expected that the response would be part of the brain’s sophisticated system for monitoring energy levels during exercise,” says Dr Stinear.

“Seeing the same effect in fresh muscle suggests that it’s more of a simple reflex – part of our basic wiring – and it appears that very ancient parts of the brain such as the brainstem are involved. Reflexive movements in response to touch, vision and hearing are well known but this is the first time that a reflex linking taste and muscle activity has been described,” she says.

Further research is required to determine the precise mechanisms involved and to learn more about the size of the effect on fresh versus fatigued muscle.

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Article adapted by MD Sports from original press release.
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Contact: Pauline Curtis
The University of Auckland

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Researchers at The University of Auckland have shown for the first time that the mere presence of carbohydrate solution in the mouth immediately boosts muscle strength, even before it is swallowed.

The results suggest that a previously unknown neural pathway is activated when receptors in the mouth detect carbohydrate, stimulating parts of the brain that control muscle activity and producing an increase in muscle strength.

Previous research had shown that the presence of carbohydrate in the mouth can improve physical performance during prolonged activity, but the mechanism involved was not known and it was unclear whether a person must be fatigued for the effect to be seen.

“There appears to be a pathway in the brain that tells our muscles when energy is on the way,” says lead researcher Dr Nicholas Gant from the Department of Sport and Exercise Science.

“We have shown that carbohydrate in the mouth produces an immediate increase in neural drive to both fresh and fatigued muscle and that the size of the effect is unrelated to the amount of glucose in the blood or the extent of fatigue.”

The current research has been published in the journal Brain Research and has also captured the attention of New Scientist magazine.

In the first of two experiments, 16 healthy young men who had been doing biceps exercises for 11 minutes were given a carbohydrate solution to drink or an identically flavored energy-free placebo. Their biceps strength was measured before and immediately afterward, as was the activity of the brain pathway known to supply the biceps.

Around one second after swallowing the drink, neural activity increased by 30 percent and muscle strength two percent, with the effect lasting for around three minutes. The response was not related to the amount of glucose in the bloodstream or how fatigued the participants were.

“It might not sound like much, but a two percent increase in muscle strength is enormous, especially at the elite level. It’s the difference between winning an Olympic medal or not,” says co-author Dr Cathy Stinear.

As might be expected, a second boost in muscle strength was observed after 10 minutes when carbohydrate reached the bloodstream and muscles through digestion, but no additional boost in neural activity was seen at that time.

“Two quite distinct mechanisms are involved,” says Dr Stinear. “The first is the signal from the mouth via the brain that energy is about to be available and the second is when the carbohydrate actually reaches the muscles and provides that energy,” says Dr Stinear.

“The carbohydrate and placebo solutions used in the experiment were of identical flavor and sweetness, confirming that receptors in the mouth can process other sensory information aside from the basic taste qualities of food. The results suggest that detecting energy may be a sixth taste sense in humans,” says Dr Gant.

In the second experiment, 17 participants who had not been doing exercise and were not fatigued simply held one of the solutions in their mouths without swallowing. Measurements of the muscle between the thumb and index finger were taken while the muscle was either relaxed or active.

A similar, though smaller effect was observed as in the first experiment, with a nine percent increase in neural activity produced by the carbohydrate solution compared with placebo. This showed that the response is seen in both large powerful muscles and in smaller muscles responsible for fine hand movements.

“Together the results show that carbohydrate in the mouth activates the neural pathway whether or not muscles are fatigued. We were surprised by this, because we had expected that the response would be part of the brain’s sophisticated system for monitoring energy levels during exercise,” says Dr Stinear.

“Seeing the same effect in fresh muscle suggests that it’s more of a simple reflex – part of our basic wiring – and it appears that very ancient parts of the brain such as the brainstem are involved. Reflexive movements in response to touch, vision and hearing are well known but this is the first time that a reflex linking taste and muscle activity has been described,” she says.

Further research is required to determine the precise mechanisms involved and to learn more about the size of the effect on fresh versus fatigued muscle.

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Article adapted by MD Sports from original press release.
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Contact: Pauline Curtis
The University of Auckland

ATHENS, Ohio – Men over 60 may be able to increase their strength by as much as 80 percent by performing intense weight training exercises, according to physiologists involved in studies of the health benefits of weight lifting. The researchers also have found that older men gain strength at the same rate as men in their 20s.

In a study of 18 men ages 60 to 75, Ohio University physiologists found that subjects who participated in a 16-week, high-intensity resistence training program on average were 50 percent to 80 percent stronger by the end of the study. None of the participants had engaged in weight lifting prior to the study. Researchers also observed improvements in the seniors’ muscle tone, aerobic capacity and cholesterol profile.

These are some of the latest findings from a decades-long examination of the impact of exercise on the health of men and women of all ages. When researchers compared the strength gains of the elderly participants in this study to findings from other studies they’ve done of college-age men, they found that changes in strength and muscle size were similar in both age groups. The findings were published in a recent issue of the Journal of Gerontology.

“There have been a number of research projects that have come out over the years that suggest there is no age limitation to getting stronger from resistance training,” said Robert Staron, co-author of this study and an associate professor of anatomy in the university’s College of Osteopathic Medicine. “It’s become obvious that it’s important to maintain a certain amount of muscle mass as we age.”

This new study also suggests that elderly men can handle heavy workloads over a long period of time. Participants – who all were in good health and closely monitored during testing and training – performed leg presses, half squats and leg extensions twice a week to exercise the lower body. When the men began the study, they were able to leg press about 375 pounds on average. After the 16-week period, they could take on about 600 pounds. Studies elsewhere have involved low-intensity exercises over a shorter term.

In addition to the increase in strength, researchers found that weight lifting had a beneficial impact on the participants’ cardiovascular system. Tests on an exercise treadmill showed that their bodies used oxygen more efficiently after weight training.

“The individuals run until they are completely exhausted, and it took longer for them to reach that point after resistance training,” Staron said.

Blood samples taken before and after weight training also showed favorable changes in participants’ overall cholesterol profiles, he said, including increases in HDL cholesterol levels and decreases in LDL cholesterol levels.

Losing muscle tone and strength is not uncommon for many senior citizens, Staron said, but this research suggests that a lack of physical exercise can contribute to the problem.

“Certainly, inactivity does play a role in contributing to the decrease in muscle mass,” Staron said. “If we can maintain a certain level of strength through exercise, our quality of life should be better as we age.”

Before beginning a weight lifting regimen, it’s a good idea to consult a physician, Staron advised, adding that it’s also important to learn proper weight lifting techniques. Staron and his colleagues now have turned their attention to how certain weight training routines impact young people.

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Article adapted by MD Sports from original press release.
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Contact: Andrea Gibson
Ohio University

Collaborators on this project are Fredrick Hagerman, Robert Hikida and Thomas Murray of the College of Osteopathic Medicine, former graduate student Seamus Walsh, Roger Gilders of the College of Health and Human Services, Kumika Toma of the College of Arts and Sciences and Kerry Ragg of the Student Health Service.

The University of Manchester is investigating whether increasing the testosterone levels of frail elderly men could improve their strength, energy and mobility.

This is the first study in the world to examine how testosterone treatment may impact this age-group, led by Professor Fred Wu of the Department of Endocrinology at Manchester Royal Infirmary.

Professor Wu said: “Levels of the male hormone testosterone fall by about 1% a year in men over 40, leading to decreases in muscle size and strength, increased body fat and thinner bones. The changes are also associated with decreased sexual interest, fatigue, mobility problems, depression, increased risk of falling and a general sense of weakness.

“Tests on younger and healthy older men suggest that testosterone replacement could help reverse these symptoms in the frail and elderly.”

Professor Wu’s team is expecting to publish the results in two years’ time, and hopes that if the treatment is proven to be effective it may be adopted as standard practice by the NHS.

As well as increasing strength, mobility and quality of life for elderly men, the move could significantly reduce the accident-rate and care requirements of this group and ultimately reduce demands on the NHS and social services.

Men aged 65+ who have lost weight, are easily tired, slow in walking and feel generally weak for no specific reason are being recruited for the study. Only those volunteers found to have low testosterone levels can be included in the trial.

The protocol for participants requires five visits to the Wellcome Trust Clinical Research Facility on Grafton Street at Manchester Royal Infirmary over the 12 month period. They will receive either testosterone or a dummy placebo in the form of a gel self-applied daily to the skin, for the first six months of the trial. Their muscle strength, mobility, bone-strength, muscle and fat content and general quality of life will then be assessed by the research team after both six and 12 months.

The research is being undertaken in partnership with Central Manchester and Manchester Children’s University Hospitals NHS Trust. Participants are free to withdraw from the study at any time, and all information will be collected in the strictest confidence.

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Article adapted by MD Sports from original press release.
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Contact: Jo Nightingale or Rachael McGraw
University of Manchester

NOTES FOR EDITORS

The University of Manchester (www.manchester.ac.uk) was formed by the merger of The Victoria University of Manchester and UMIST in October 2004, and with 36,000 students is the largest higher education institution in the country. Its Faculty of Medical & Human Sciences (www.mhs.manchester.ac.uk) is one of the largest faculties of clinical and health sciences in Europe, with a research income of over £37 million.

The School of Medicine (www.medicine.manchester.ac.uk) is the largest of the Faculty’s five Schools, with 1300 staff, almost 2000 undergraduates and a £32M research income. The School encompasses five teaching hospitals, and is closely linked to a range of general hospitals and community practices across the North West of England.

New study dispels belief that increasing the hormone level improves the sexual function

Bethesda, Md.— The American Journal of Physiology: Endocrinology and Metabolism, one of the 14 peer-reviewed journals published by the American Physiological Society (APS), spotlights recent research findings designed to improve and understand human well-being and health. A study in the December edition examines how different doses of testosterone affect body composition, muscle size, strength, and sexual functions.

Background

Testosterone regulates many physiological processes, including muscle protein metabolism, some aspects of sexual and cognitive functions, secondary sex characteristics, erythropoiesis, plasma lipids, and bone metabolism. However, testosterone dose dependency of various hormonal dependent functions has not been well understood in the scientific community. Previous studies reveal that administration of replacement doses of testosterone to hypogonadal men and of supraphysiological doses to eugonadal men increases fat-free mass, muscle size, and strength. Conversely, suppression of endogenous testosterone concentrations is associated with loss of fat-free mass and a decrease in fractional muscle protein synthesis.

What is not known is whether testosterone effects on the muscle are dose dependent, or the nature of the testosterone dose-response relationships. Animal studies suggest that different androgen-dependent processes have different androgen dose-response relationships. Sexual function in male mammals is maintained at serum testosterone concentrations that are at the lower end of the male range. However, it is not known whether the low normal testosterone levels that normalize sexual function are sufficient to maintain muscle mass and strength, or whether the higher testosterone concentrations required to maintain muscle mass and strength might adversely affect plasma lipids, hemoglobin levels, and the prostate.

The Study

The primary objective of this study was to determine the dose dependency of testosterone’s effects on fat-free mass and muscle performance. The authors hypothesized that changes in circulating testosterone concentrations would be associated with dose-dependent changes in fat-free mass, muscle strength, and power in conformity with a single linear dose-response relationship, and that the dose requirements for maintaining other androgen-dependent processes would be different.

Young men were treated with a long-acting gonadotropin-releasing hormone (GnRH) agonist to suppress endogenous testosterone secretion, and concomitantly also with one of five testosterone-dose regimens to create different levels of serum testosterone concentrations extending from subphysiological to the supraphysiological range. The lowest testosterone dose, 25 mg weekly, was selected because this dose had been shown to maintain sexual function in GnRH antagonist-treated men. The selection of the 600-mg weekly dose was based on the consideration that this was the highest dose that had been safely administered to men in controlled studies.

The authors of the study, “Testosterone Dose-Response Relationships in Healthy Young Men” are Shalender Bhasin, Linda Woodhouse, Connie Dzekov, Jeanne Dzekov, Indrani Sinha-Hikim, Ruoquing Shen, and Atam B. Singh, all from the Division of Endocrinology, Metabolism, and Molecular Medicine, Charles R. Drew University of Medicine and Science, Los Angeles, CA; Richard Casaburi, Dimple Bhasin, Nancy Berman, Rachelle Bross and Jeffrey Phillips, from the Harbor-University of California Los Angeles Medical Center, Torrance, CA; Xianghong Chen and Kevin E. Yarasheski at the Biomedical Mass Spectrometric Research Resource, Department of Internal Medicine, Washington University, School of Medicine, St. Louis, Missouri, Lynne Magliano and Thomas W. Storer, from the Laboratory for Exercise Sciences, El Camino College, El Camino, CA.

Protocol

This was a double-blind, randomized study consisting of a four-week control period, a 20-week treatment period, and a 16-week recovery period. The participants were healthy men, 18-35 years of age, with prior weight-lifting experience and normal testosterone levels. These men had not used any anabolic agents and had not participated in competitive sports events in the preceding year, and they were not planning to participate in competitive events in the following year. The participants were asked not to undertake strength training or moderate-to-heavy endurance exercise during the study. These instructions were reinforced every four weeks.

Sixty-one eligible men were randomly assigned to one of five groups. All received monthly injections of a long-acting GnRH agonist to suppress endogenous testosterone production. In addition, group 1 received 25 mg of testosterone enanthate intramuscularly weekly; group 2, 50 mg testosterone enanthate; group 3, 125 mg testosterone enanthate; group 4, 300 mg testosterone enanthate; and group 5, 600 mg testosterone enanthate. Twelve men were assigned to group 1, 12 to group 2, 12 to group 3, 12 to group 4, and 13 to group 5.

Nutritional Intake

Energy and protein intakes were standardized at 36 kcal/kg. The standardized diet was initiated two weeks before treatment started; dietary instructions were reinforced every four weeks. The nutritional intake was verified by analysis of three-day food records and 24-hour food recalls every four weeks.

Outcome Measures

Body composition and muscle performance were assessed at baseline and during week 20. Fat-free mass and fat mass were measured by underwater weighing and dual-energy X-ray absorptiometry. Total thigh muscle and quadriceps muscle volumes were measured by MRI scanning.

For estimation of total body water, the men ingested 10 g of 2H2O, and plasma samples were drawn at 0, 120, 180, and 240 min. A measurement of 2H abundance in plasma was made by nuclear magnetic resonance spectroscopy, with a correction factor of 0.985 for exchangeable hydrogen. Another measure of bilateral leg press strength was taken by use of the one-repetition maximum (1-RM) method. A seated leg press exercise with pneumatic resistance was used for this purpose. Subjects performed 5-10 min of leg cycling and stretching warm-up and received instruction and practice in lifting mechanics before performing progressive warm-up lifts leading to the 1-RM. Seat position and the ensuing knee and hip angles, as well as foot placement, were measured and recorded for use in subsequent testing. To ensure reliability in this highly effort-dependent test, the 1-RM score was reassessed within seven days, but not sooner than two days, after the first evaluation. If duplicate scores were within five percent, the higher of the two values was accepted as the strength score. If the two tests differed by greater than five percent, additional studies were conducted.

Sexual function was assessed by daily logs of sexual activity and desire that were maintained for seven consecutive days at baseline and during treatment by use of a published instrument. Spatial cognition was assessed by a computerized checkerboard test and mood by Hamilton’s depression and Young’s mania scales.

Adverse experiences, blood counts and chemistries, prostate-specific antigen (PSA), plasma lipids, total and free testosterone, luteinizing hormone (LH), sex steroid-binding globulin (SHBG), and insulin-like growth factor I (IGF-I) levels were measured periodically during control and treatment periods. Serum total testosterone was measured by an immunoassay.

Results

Of 61 men enrolled, 54 completed the study: 12 in group 1, 8 in group 2, 11 in group 3, 10 in group 4, and 13 in group 5. One man discontinued treatment because of acne; other subjects were unable to meet the demands of the protocol. The five groups did not significantly differ with respect to their baseline characteristics. Key findings included:

– Compliance: All evaluable subjects received 100percent of their GnRH agonist injections, and only one man in the 125-mg group missed one testosterone injection.

– Nutritional intake: Daily energy intake and proportion of calories derived from protein, carbohydrate, and fat were not significantly different among the five groups at baseline. There was no significant change in daily caloric, protein, carbohydrate, or fat intake in any group during treatment.

– Hormone levels: Serum total and free testosterone levels, measured during week 16, one week after the previous injection, were linearly dependent on the testosterone dose (P = 0.0001). Serum total and free testosterone concentrations decreased from baseline in men receiving the 25- and 50-mg doses and increased at 300- and 600-mg doses. Serum LH levels were suppressed in all groups. Serum SHBG levels decreased dose dependently at the 300- and 600-mg doses but did not change in other groups. Serum IGF-I concentrations increased dose dependently at the 300- and 600-mg doses.

– Body composition: Fat-free mass, measured by underwater weighing, did not change significantly in men receiving the 25- or 50-mg testosterone dose, but it increased dose dependently at higher doses. The changes in fat-free mass were highly dependent on testosterone dose (P = 0.0001) and correlated with log total testosterone concentrations during treatment (r = 0.73, P = 0.0001). Fat mass, measured by underwater weighing, increased significantly in men receiving the 25- and 50-mg doses, but did not change in men receiving the higher doses of testosterone. There was an inverse correlation between change in fat mass by underwater weighing and log testosterone concentrations.

– Muscle size: The thigh muscle volume and quadriceps muscle volume did not significantly change in men receiving the 25- or 50-mg doses but increased dose-dependently at higher doses of testosterone. The changes in thigh muscle and quadriceps muscle volumes correlated with log testosterone levels during treatment.

– Muscle performance: The leg press strength did not change significantly in the 25- and 125-mg-dose groups but increased significantly in those receiving the 50-, 300-, and 600-mg doses. Leg power did not change significantly in men receiving the 25-, 50-, and 125-mg doses of testosterone weekly, but it increased significantly in those receiving the 300- and 600-mg doses. The increase in leg power correlated with log testosterone concentrations and changes in fat-free mass and muscle strength.

– Behavioral measures: The scores for sexual activity and sexual desire measured by daily logs did not change significantly at any dose. Similarly, visual-spatial cognition and did not change significantly in any group.

– Adverse experiences and safety measures: Hemoglobin levels decreased significantly in men receiving the 50-mg dose but increased at the 600-mg dose; the changes in hemoglobin were positively correlated with testosterone concentrations. Changes in plasma HDL cholesterol, in contrast, were negatively dependent on testosterone dose and correlated with testosterone concentrations. Total cholesterol, plasma low-density lipoprotein cholesterol, and triglyceride levels did not change significantly at any dose. Serum PSA, creatinine, bilirubin, alanine aminotransferase, and alkaline phosphatase did not change significantly in any group, but aspartate aminotransferase decreased significantly in the 25-mg group. Two men in the 25-mg group, five in the 50-mg group, three in the 125-mg group, seven in the 300-mg group, and two in the 600-mg group developed acne. One man receiving the 50-mg dose reported decreased ability to achieve erections.

Discussion

The researchers found that GnRH agonist administration suppressed endogenous LH and testosterone secretion. Therefore, circulating testosterone concentrations during treatment were proportional to the administered dose of testosterone enanthate. This strategy of combined administration of GnRH agonist and graded doses of testosterone enanthate was effective in establishing different levels of serum testosterone concentrations among the five treatment groups. The different levels of circulating testosterone concentrations created by this regimen were associated with dose- and concentration-dependent changes in fat-free mass, fat mass, thigh and quadriceps muscle volume, muscle strength, leg power, hemoglobin, circulating IGF-I, and plasma HDL cholesterol.

Serum PSA levels, sexual desire and activity, and spatial cognition did not change significantly at any dose. The changes in fat-free mass, muscle volume, leg press strength and power, hemoglobin, and IGF-I were positively correlated, whereas changes in plasma HDL cholesterol and fat mass were negatively correlated with testosterone dose and total and free testosterone concentrations during treatment.

There were no significant changes in overall sexual activity or sexual desire in any group, including those receiving the 25-mg dose. Testosterone replacement of hypogonadal men improves frequency of sexual acts and fantasies, sexual desire, and response to visual erotic stimuli. The data demonstrate that serum testosterone concentrations at the lower end of male range can maintain some aspects of sexual function.

Conclusions

This study demonstrates that an increase in circulating testosterone concentrations results in dose-dependent increases in fat-free mass, muscle size, strength, and power. The relationships between circulating testosterone concentrations and changes in fat-free mass and muscle size conform to a single log-linear dose-response curve. The data do not support the notion of two separate dose-response curves reflecting two independent mechanisms of testosterone action on the muscle.

In addition, the study could not determine if responsiveness to testosterone is attenuated in older men. Testosterone dose-response relationships might be modulated by other muscle growth regulators, such as nutritional status, exercise and activity level, glucocorticoids, thyroid hormones, and endogenous growth hormone secretory status. Serum PSA levels decrease after androgen withdrawal, and testosterone replacement of hypogonadal men increases PSA levels into the normal range.

The data demonstrate that different androgen-dependent body functions respond differently to different testosterone dose-response relationships. Some aspects of sexual function and spatial cognition, and PSA levels, were maintained by relatively low doses of testosterone in GnRH agonist-treated men and did not increase further with administration of higher doses of testosterone. In contrast, graded doses of testosterone were associated with dose and testosterone concentration-dependent changes in fat-free mass, fat mass, muscle volume, leg press strength and power, hemoglobin, IGF-I, and plasma HDL cholesterol.

Testosterone doses associated with significant gains in fat-free mass, muscle size, and strength were associated with significant reductions in plasma HDL concentrations. Further studies are needed to determine whether clinically significant anabolic effects of testosterone can be achieved without adversely affecting cardiovascular risk. Selective androgen receptor modulators that preferentially augment muscle mass and strength, but only minimally affect prostate and cardiovascular risk factors, are desirable.

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Article adapted by MD Sports from original press release.
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Contact: Donna Krupa
American Physiological Society

Source: American Journal of Physiology: Endocrinology and Metabolism, December 2001

The American Physiological Society (APS) was founded in 1887 to foster basic and applied science, much of it relating to human health. The Bethesda, MD-based Society has more than 10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals every year.

Experts at The University of Nottingham are to investigate the effect of nutrients on muscle maintenance in the hope of determining better ways of keeping up our strength as we get old.

The researchers, based at the School of Graduate Entry Medicine and Health in Derby, want to know what sort of exercise we can take and what food we should eat to slow down the natural loss of skeletal muscle with ageing.

The team from the Department of Clinical Physiology, which has over 20 years experience in carrying out this type of metabolic study, need to recruit 16 healthy male volunteers in two specific age groups to help in it’s research.

Skeletal muscles make up about half of our body weight and are responsible for controlling movement and maintaining posture. However, at around 50 years of age our muscles begin to waste at approximately 0.5 per cent to one per cent a year. It means that an 80 year old may only have 70 per cent of the muscle of a 50 year old.

Since the strength of skeletal muscle is proportional to muscle size, such wasting makes it harder to carry out daily activities requiring strength, such as climbing stairs and leads to a loss of independence and an increased risk of falls and fractures.

In order for skeletal muscles to maintain their size, the large reservoirs of muscle protein require constant replenishment in the way of amino acids from protein contained within the food we eat. In fact, amino acids from our food act not only as the building blocks of muscle proteins but also actually ‘tell’ our muscle cells to build proteins.

Recent research from the clinical physiology team has shown that the cause of muscle wasting with ageing appears to be an attenuation of muscle building in response to protein feeding. In other words, as we age we lose the ability to covert the protein in the food we eat in to muscle tissue. The proposed research will investigate the mechanisms responsible for this deficit.

Dr Philip Atherton, who is currently recruiting volunteers, said: “I am really excited to be involved in this project because if we can determine ways to better maintain muscle mass as we age it will greatly benefit us all.”

The researchers are looking for 16 healthy, non-smoking, male volunteers aged 18 to 25 and 65 to 75.

Initially, the volunteers will undergo a health screening and then on a different day, under the supervision of a doctor, will be infused with an amino acid mixture to simulate feeding along with a ‘tagged’ amino acid that allows them to assess muscle building. To make these measures, blood samples will be taken from the arm and muscle biopsies from the thigh muscle under local anaesthesia. Volunteers will receive an honorarium to cover their expenses.

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Article adapted by MD Sports from original press release.
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Contact: Lindsay Brooke
University of Nottingham

 

The study will take place at The University of Nottingham’s Medical School which based at the City Hospital in Derby.

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

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

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

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

Caffeine aids carbohydrate uptake  

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

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

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

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

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

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

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

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

Lower dose is next step  

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

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

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

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

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