Archive for the ‘Fiber’ 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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Don’t drink alcohol. Take vitamins. Avoid eating eggs. We’ve heard these pieces of nutritional advice for years – but are they accurate?

Not necessarily, say two exercise physiologists who presented at the American College of Sports Medicine (ACSM) 11th-annual Health & Fitness Summit & Exposition in Dallas, Texas. Wendy Repovich, Ph.D., FACSM, and Janet Peterson, Dr.P.H., FACSM, set out to debunk the “Top 10 Nutrition Myths.”

According to Repovich and Peterson, these nutrition myths are:

10. Eating carbohydrates makes you fat. Cutting carbs from your diet may have short-term weight loss benefits due to water loss from a decrease in carbohydrate stores, but eating carbs in moderation does not directly lead to weight gain. The body uses carbs for energy, and going too long without them can cause lethargy.

9. Drink eight, 8-oz. glasses of water per day. You should replace water lost through breathing, excrement and sweating each day – but that doesn’t necessarily total 64 ounces of water. It’s hard to measure the exact amount of water you have consumed daily in food and drink, but if your urine is pale yellow, you’re doing a good job. If it’s a darker yellow, drink more H2O.

8. Brown grain products are whole grain products. Brown dyes and additives can give foods the deceiving appearance of whole grain. Read labels to be sure a food is whole grain, and try to get three-ounce equivalents of whole grains per day to reduce the risk of heart disease, diabetes, and stroke.

7. Eating eggs will raise your cholesterol. This myth began because egg yolks have the most concentrated amount of cholesterol of any food. However, there’s not enough cholesterol there to pose health risks if eggs are eaten in moderation. Studies suggest that eating one egg per day will not raise cholesterol levels and that eggs are actually a great source of nutrients.

6. All alcohol is bad for you. Again, moderation is key. Six ounces of wine and 12 ounces of beer are considered moderate amounts, and should not pose any adverse health effects to the average healthy adult. All alcohol is an anticoagulant and red wine also contains antioxidants, so drinking a small amount daily can be beneficial.

5. Vitamin supplements are necessary for everyone. If you eat a variety of fruits, vegetables, and whole grains, along with moderate amounts of a variety of low-fat dairy and protein and the right quantity of calories, you don’t need to supplement. Most Americans do not, so a multi-vitamin might be good. Special vitamin supplements are also recommended for people who are pregnant or have nutritional disorders.

4. Consuming extra protein is necessary to build muscle mass. Contrary to claims of some protein supplement companies, consuming extra protein does nothing to bulk up muscle unless you are also doing significant weight training at the same time. Even then the increased requirement can easily come from food. A potential problem with supplements is the body has to work overtime to get rid of excess protein, and can become distressed as a result.

3. Eating fiber causes problems if you have irritable bowel syndrome (IBS). There are two kinds of fiber: soluble and insoluble. Insoluble fiber can cause problems in IBS sufferers; soluble fiber, however, is more easily absorbed by the body and helps prevent constipation for those with IBS. Soluble fiber is found in most grains.

2. Eating immediately after a workout will improve recovery. Endurance athletes need to take in carbohydrates immediately after a workout to replace glycogen stores, and a small amount of protein with the drink enhances the effect. Drinking low-fat chocolate milk or a carbohydrate drink, like Gatorade, is better for the body, as they replace glycogen stores lost during exercise. Protein is not going to help build muscle, so strength athletes do not need to eat immediately following their workout.

1. Type 2 diabetes can be prevented by eating foods low on the glycemic index. High levels of glucose are not what “cause” diabetes; the disease is caused by the body’s resistance to insulin. Foods high on the glycemic index can cause glucose levels to spike, but this is just an indicator of the presence of diabetes, not the root cause.

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Article adapted by MD Sports Weblog from original press release.
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Contact: Communications and Public Information
American College of Sports Medicine

The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 20,000 International, National and Regional members are dedicated to promoting and integrating scientific research, education and practical applications of sports medicine and exercise science to maintain and enhance physical performance, fitness, health and quality of life.