Posts Tagged ‘muscle strength’

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

USC study finds combining resistance training and androgens gives more muscular bang for the buck

PHILADELPHIA (June 19, 2003)-Men who take supplemental androgens-the male hormone testosterone or similar medications-increase their strength by adding muscle mass, but androgens alone do not pack more might into the muscles, according to studies presented today by University of Southern California researchers.

Treatment with androgens increases lean body mass-which encompasses everything in the body but bone and fat-and strength increases proportionately with the amount of muscle added, says E. Todd Schroeder, Ph.D., postdoctoral fellow in the Department of Medicine at the Keck School of Medicine of USC and adjunct assistant professor in the USC Department of Biokinesiology and Physical Therapy. Schroeder presented his findings at the Endocrine Society’s 85th Annual Meeting.

However, when men use androgen therapy combined with resistance training, such as weightlifting, their gains in strength may far outpace the amount of muscle that can be added with androgens alone. Each muscle cell packs a bigger punch, a concept known as improved muscle quality.

“The results of androgen therapy alone on muscle and strength are not necessarily bad, but they are not optimal,” Schroeder says. “The men did improve their strength, but it was proportional to the muscle mass they added.”

The findings wield health implications beyond the stereotypes of muscle-bound bodybuilders. Schroeder and his colleagues are studying the usefulness of androgens and exercise in helping maintain muscle strength, muscle power and physical function among seniors, for example. They also have studied androgen therapy’s effectiveness in battling wasting among HIV-positive patients.

In their recent study, Schroeder and USC colleagues Michael Terk, M.D., and Fred R. Sattler, M.D., looked at both young men and seniors. They followed two groups: 33 seniors ranging from their mid-60s to late 70s, and 23 HIV-positive men ranging from their early 30s to late 40s.

The younger men were randomly assigned to get 600 milligrams (mg) each week of nandrolone alone or in combination with resistance training. The older men were randomly assigned to receive 20 mg a day of oxandrolone or a placebo. These pharmacologic androgen doses were given over 12 weeks.

Researchers determined maximal strength-the most weight a participant could safely lift or push-using leg press, leg extension and leg flexion machines.

The researchers also measured the cross-sectional area of participants’ thighs and the lean body mass of their lower extremities by magnetic resonance imaging, or MRI. They then determined the strength that participants exerted for each unit of muscle (muscle quality) and how muscle quality changed over time.

Androgens alone increased lean body mass and maximum strength in both groups of men, but “gains were modest,” Schroeder says, and muscle quality did not change, since the muscle size and strength both increased proportionately. However, among those using nandrolone and undergoing resistance training, muscle quality improved significantly: Gains in strength were much greater than the gains that could occur from muscle-mass increase alone.

“It is clear from our studies and others that resistance training is critical for increasing muscle quality, but the effects can probably be augmented with androgens,” Schroeder says. “In addition, not everyone can do resistance training, and a short course of androgens can help get people stronger and more functional.”

Finally, results provide researchers insight into how to better design future studies to test strategies to best preserve and even improve muscle strength and physical function among seniors. Similar studies will be important for other types of patients who experience muscle loss and frailty, such as those with cancer, chronic lung disease, chronic renal failure and other conditions.

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Article adapted by MD Sports from original press release.
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Contact: Jon Weiner
University of Southern California

Grants by the National Institute of Diabetes & Digestive & Kidney Diseases and the National Center for Research Resources (General Clinical Research Center) supported the research. Bio Technology General Corp., which makes Oxandrin (oxandrolone), also supported part of the research.

Edward T. Schroeder, Michael Terk and Fred R. Sattler, “Pharmacological Doses of Androgen Do Not Improve Muscle Quality in Young or Older Men: Results from Two Studies,” Endocrine Society’s 85th Annual Meeting, poster P3-212, presentation 11 a.m., June 21. Findings released at news conference 1:30 p.m., June 19.

    Creatine, a popular nutritional supplement used by weightlifters and sprinters to improve athletic performance, could lend muscle strength to people with muscular dystrophies.

    Muscle strength increased by an average of 8.5 percent among patients taking creatine, compared to those who did not use the supplement, according to a recent review of studies. Creatine users also gained an average of 1.4 pounds more lean body mass than nonusers.

    The evidence from the studies “shows that short- and medium-term creatine treatment improves muscle strength in people with muscular dystrophies and is well-tolerated,” said lead reviewer Dr. Rudolf Kley of Ruhr University Bochum in Germany.

    The review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

    Creatine is found naturally in the body, where it helps supply energy to muscle cells. Athletes looking for short bursts of intense strength have used creatine in powders or pills for decades, but the supplement became more popular after the 1992 Barcelona Olympics, when sprinters, rowers and cyclists went public with their creatine regimens.

    Although creatine has been widely studied as a performance enhancer, it’s still not clear if the supplement makes a difference, according to Roger Fielding, Ph.D., of Tufts University, who has also recently written a review of creatine treatments for neuromuscular diseases.

    People with muscular dystrophies can have lower-than-normal levels of creatine, along with increasing muscle weakness as their disease progresses. Since some studies suggest that creatine improves muscle performance in healthy people, many researchers have reasoned that it might be helpful in treating muscle disease.

    The Cochrane researchers reviewed 12 studies that included 266 people with different types of muscular dystrophy. People in the studies who took creatine supplements used them for three weeks to six months.

    In muscular dystrophies, the proteins that make up the muscles themselves are either missing or damaged. In a related group of disorders called metabolic myopathies, the chemicals that help muscles operate go awry.

    Although creatine seemed to help many patients with muscular dystrophies, those with metabolic myopathies gained no more muscle strength or lean body mass than patients who did not use the supplement.

    The reason for the contrasting results — creatine’s “fairly consistent” effects in muscular dystrophy and lack of effectiveness in metabolic diseases — is “not entirely clear,” Kley said, calling for more research on treatment for metabolic disorders.

    The review was supported by the Neuromuscular Center Ruhrgebiet/Kliniken Bergmannsheil, at Ruhr-University Bochum and the Hamilton Health Sciences Corporation, in Canada. Kley and colleagues have each participated in trials of creatine treatment for muscle disorders, although none of the studies was sponsored by a maker of creatine.

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    Article adapted by MD Sports from original press release.
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    FOR MORE INFORMATION
    Health Behavior News Service: hbns-editor@cfah.org

    Kley RA, Vorgerd M, Tarnopolsky MA. Creatine for treating muscle disorders. Cochrane Database of Systematic Reviews 2007, Issue 1.

    The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. Visit http://www.cochrane.org for more information.