Cereal and Milk Good for Exercise Muscle Recovery

Cereal and non-fat milk is as good as a commercially-available sports drink in initiating post-exercise muscle recovery.

Background

This study compared the effects of ingesting cereal and nonfat milk (Cereal) and a carbohydrate-electrolyte sports drink (Drink) immediately following endurance exercise on muscle glycogen synthesis and the phosphorylation state of proteins controlling protein synthesis: Akt, mTOR, rpS6 and eIF4E.

Methods

Trained cyclists or triathletes (8 male: 28.0+/-1.6 yrs, 1.8+/-0.0 m, 75.4+/-3.2 kg, 61.0+/-1.6 ml O2 * kg-1 * min-1; 4 female: 25.3+/-1.7 yrs, 1.7+/-0.0 m, 66.9+/-4.6 kg, 46.4+/-1.2 mlO2 * kg-1 * min-1) completed two randomly-ordered trials serving as their own controls. After 2 hours of cycling at 60-65% VO2MAX, a biopsy from the vastus lateralis was obtained (Post0), then subjects consumed either Drink (78.5 g carbohydrate) or Cereal (77 g carbohydrate, 19.5 g protein and 2.7 g fat). Blood was drawn before and at the end of exercise, and at 15, 30 and 60 minutes after treatment. A second biopsy was taken 60 minutes after supplementation (Post60). Differences within and between treatments were tested using repeated measures ANOVA.

Results

At Post60, blood glucose was similar between treatments (Drink 6.1+/-0.3, Cereal 5.6+/-0.2 mmol/L, p<.05), but after Cereal, plasma insulin was significantly higher (Drink 123.1+/-11.8, Cereal 191.0+/-12.3 pmol/L, p<.05), and plasma lactate significantly lower (Drink 1.4+/-0.1, Cereal 1.00+/-0.1 mmol/L, p<.05). Except for higher phosphorylation of mTOR after Cereal, glycogen and muscle proteins were not statistically different between treatments. Significant Post0 to Post60 changes occurred in glycogen (Drink 52.4+/-7.0 to 58.6+/-6.9, Cereal 58.7+/-9.6 to 66.0+/-10.0 mumol/g, p<.05) and rpS6 (Drink 17.9+/-2.5 to 35.2+/-4.9, Cereal 18.6+/-2.2 to 35.4+/-4.4 %Std, p<.05) for each treatment, but only Cereal significantly affected glycogen synthase (Drink 66.6+/-6.9 to 64.9+/-6.9, Cereal 61.1+/-8.0 to 54.2+/-7.2%Std, p<.05), Akt (Drink 57.9+/-3.2 to 55.7+/-3.1, Cereal 53.2+/-4.1 to 60.5+/-3.7 %Std, p<.05) and mTOR (Drink 28.7+/-4.4 to 35.4+/-4.5, Cereal 23.0+/-3.1 to 42.2+/-2.5 %Std, p<.05). eIF4E was unchanged after both treatments.

Conclusion

These results suggest that Cereal is as good as a commercially-available sports drink in initiating post-exercise muscle recovery.

Author: Lynne Kammer, Zhenping Ding, Bei Wang, Daiske Hara, Yi-Hung Liao and John L. Ivy

Credits/Source: Journal of the International Society of Sports Nutrition 2009, 6:11

Caffeine taken with carbohydrates increase muscle energy 66%

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 http://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.

Candy Bars Not Much Different Than Energy Bars For Athletes

Energy bars, touted for improving athletic performance while providing the right combination of essential nutrients, may not always give endurance athletes the boost they expect.An Ohio State University researcher compared two popular energy bars and found that one of the bars didn’t give the moderate increase in blood sugar known to enhance performance in endurance athletes. Instead, its effect was much like a candy bar – giving a big rush of sugar to the blood, followed by a sharp decline.

“Theoretically, energy bars produce more moderate increases and decreases in blood sugar levels than a typical candy bar,” said Steve Hertzler, an associate professor of medical dietetics at Ohio State. “But these claims aren’t necessarily valid.” His study appears in a recent issue of the Journal of the American Dietetic Association.

Hertzler wanted to know how energy bars affected blood glucose levels. Glucose is a sugar that provides energy to the body’s cells – for example, red-blood cells and most parts of the brain derive most of their energy from glucose.

“Athletes – especially those involved in endurance sports – want to enhance performance, and energy bars claim to help keep blood sugar levels at a moderate level,” Hertzler said.

Volunteers had to fast for at least 12 hours before taking part in each of four experiments. Then, they ate one of four experimental “meals” consisting of either four slices of white bread; a Snickers bar; an Ironman PR Bar; or a PowerBar. Each experimental meal provided the same amount of carbohydrates (50 grams.)

Hertzler then tested the effects these foods had on blood glucose levels at 15-minute intervals for up to two hours after each experimental meal. The volunteers had to wait at least 24 hours between each experimental meal.

Hertzler measured each subject’s blood samples for glucose levels, to determine which food most raised blood sugar levels.

Both energy bars caused blood glucose levels to peak at 30 minutes, while levels peaked at 45 minutes after the bread and candy bar were consumed. Blood glucose levels declined steadily throughout the duration of testing for all foods but the Ironman PR Bar. This bar caused blood glucose rates to remain fairly steady, probably because of the moderate carbohydrate level of the bar, according to Hertzler.

“Though blood glucose rates peaked at 30 minutes with both bars, the high-carbohydrate energy bar – the PowerBar – caused a much sharper decline,” Hertzler said. “In fact, the decline was sharper than with the candy bar.” Much of the energy derived from the bread and the candy bar came from carbohydrate and the same was true for the PowerBar. While the bar is low in protein and fat, more than 70 percent of it is made up of carbohydrate (such as high-fructose corn syrup; oat bran; and brown rice). In contrast, 40 percent of the Ironman PR is comprised of carbohydrate (high fructose corn syrup and fructose.) The rest of the bar was comprised of 30 percent fat and 30 percent protein.

“The composition of this bar may have been responsible for the diminished blood glucose response,” Hertzler said. “Athletes involved in short-duration events who want a quick energy boost should eat a high-carbohydrate energy bar or a candy bar,” he suggests. “However, endurance athletes would do well to consume an energy bar with a moderate carbohydrate level.”

Hertzler conducted this study while at Kent State University in Kent, Ohio. He is continuing similar research at Ohio State.

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Article adapted by MD Sports Weblog from original press release.
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Contact: Steve Hertzler
Ohio State University

Editor’s note: This research was funded by a grant from Kent State University. The researcher received no funding from either energy bar manufacturer.

Researchers discovery gene that enhances muscle performance

A team of researchers, led by scientists at Dartmouth Medical School and Dartmouth College, have identified and tested a gene that dramatically alters both muscle metabolism and performance. The researchers say that this finding could someday lead to treatment for muscle diseases, including helping the elderly who suffer from muscle deterioration and improving muscle performance in endurance athletes.

The researchers report that the enzyme called AMP-activated protein kinase (or AMPK) is directly involved in optimizing muscle activity. The team bred a mouse that genetically expressed AMPK in an activated state. Like a trained athlete, this mouse enjoyed increased capacity to exercise, manifested by its ability to run three times longer than a normal mouse before exhaustion.

One particularly striking feature of the finding was the accumulation of muscle glycogen, the stored form of carbohydrates, a condition that many athletes seek by “carbo-loading” before an event or game. The study appears in the Nov. 14 online issue of the American Journal of Physiology: Endocrinology and Metabolism.

“Our genetically altered mouse appears to have already been an exercise program,” says Lee Witters, the Eugene W. Leonard 1921 Professor of Medicine and Biochemistry at Dartmouth Medical School and professor of biological sciences at Dartmouth College. “In other words, without a prior exercise regimen, the mouse developed many of the muscle features that would only be observed after a period of exercise training.”

Witters, whose lab led the study, explains that this finding has implication for anyone with a muscle disease and especially for the growing proportion of the population that is aging. Deteriorating muscles often make the elderly much more prone to fall, leading to hip and other fractures. According to Witters, there is tremendous interest in the geriatric field to find ways to improve muscle performance.

“We now wonder if it’s possible to achieve elements of muscular fitness without having to exercise, which in turn, raises many questions about possible modes of exercise performance enhancement, including the development of drugs that could do the same thing as we have done genetically,” he says. “This also might raise to some the specter of ‘gene doping,’ something seriously being talked about in the future of high-performance athletes.”

Witters says that the carbohydrate, glucose, is a major fuel that powers muscles, and this contributes directly to a muscle’s ability to repetitively contract during exercise. The activated AMPK in the Dartmouth mouse appears to have increased glycogen content by actually switching on a gene that normally synthesizes liver glycogen.

“The switching on of this liver gene in muscles,” he says, “is a shift in the conception of the biochemistry of muscle metabolism, since many enzyme genes are thought to only be active in just one tissue.”

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Article adapted by MD Sports Weblog from original press release.
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Contact: Sue Knapp
Dartmouth College

Other authors on the paper include Laura Barré, Christine Richardson, and Steven Fiering, all at Dartmouth; Michael Hirshman and Laurie Goodyear of Joslin Diabetes Center in Boston; Joseph Brozinick with Eli Lilly and Company; and Bruce Kemp of the St. Vincent’s Institute in Australia.

This research is funded by the National Institutes of Health.