Sports Nutrition Guide Section Links
» Section 1:
An Overview Of Sports Nutrition
» Section 2: Protein & Amino Acids, mTOR, & Protein Synergy
» Section 3: Carbohydrates
» Section 4: Lipids
» Section 5: Understanding Specialty Sports Supplements
» Section 6: Sports Nutrition Guidelines (With Links to Specific Sports)
» Section 7: Special Concerns For Athletic Females
» Section 8: Conclusion
» Section 9: Glossary
» Section 10: References & Suggested Readings
Sports Nutrition Guide Online
Section 3: Carbohydrates
The second macronutrient group to be reviewed is carbohydrates, which are a major source of fuel for athletically active people and an essential part of the diet for everyone.
| What Are Macronutrients And Micronutrients?
The four macronutrients are protein (source of amino acids), carbohydrates, lipids (fats), and water - all of which you need in plentiful (hence the term 'macro') amounts each day.
Micronutrients - mainly vitamins and minerals - are needed in relatively small amounts (hence 'micro'), and have been shown to be essential to growth and development, and for good health and winning athletic performance.
Recent research has shown that the different varieties of carbohydrates - depending on when they are ingested - can either enhance or hinder performance. Knowing which carbohydrates work best can mean the difference between winning and losing. This chapter will help you determine how to use carbohydrates to enhance your performance.
[ Q ] What types of carbohydrates should I include in my diet?
A: The primary carbohydrates to include in your diet are the complex carbohydrates - starches and fiber. Starchy complex carbohydrates are chains of glucose (dextrose) that are freed up during digestion to be used for energy. Fibrous complex carbohydrates are not digested well by humans, but provide necessary bulk and have other beneficial characteristics, making them quite important to health.
Stick with food sources that are wholesome and unprocessed, such as whole grain rice, whole grain flour pastas, whole grain breads, and potatoes. These foods will provide you with fiber, which is important for proper digestion, and will keep the complex carbohydrates from digesting too rapidly.
Note, however, that just because a carbohydrate source is complex doesn't mean that it won't cause a rapid rise in your blood-sugar levels.
[ Q ] How can I tell how a carbohydrate will act in my body?
- First, it indicates the metabolic consequences that different foods can have on the body.
- Second, it helps to determine which foods should be consumed in relation to exercise sessions.
A: To determine the effect a certain carbohydrate will have on the body, nutritionists have developed the Glycemic Index. This is a method for determining the response of blood-sugar levels to various carbohydrate-rich foods.
As a general rule of eating, foods with lower glycemic index values can help you maintain a more stable blood-sugar level. In addition, these foods help prevent the overproduction of the hormone insulin, which is often associated with a rapid decrease in blood-sugar levels followed by a feeling of physical or mental fatigue.
To Search The Glycemic Index, Click Here.
The glycemic index rating system is important for athletes for two main reasons:
However, note that when carbohydrate foods are mixed with protein and fat-containing foods this will change how they are digested, and usually lower the glycemic index response. However, eating the healthier, more nutritious whole grain carbohydrate sources will provide you with health benefits in addition to performance benefits from the nutrition the provide, when compared to refined carbohydrate foods.
In general, high carbohydrate foods that are processed and high in sugar or glucose will raise blood sugar levels rapidly. Note that during exercise a simple carbohydrate beverage, like glucose, will actually be used by the exercising muscles independent of insulin levels. So during exercise dilute glucose beverages can help provide energy and spare your body's glycogen stores from being broken down.
| What Is Glycogen?
Glycogen is the principal stored form of carbohydrate energy (glucose), which is reserved in muscles. When your muscles are full of glycogen, they look and feel full.
During other times of the day, it is best for strive for ingesting whole grain and whole food complex carbohydrates when possible, as part of a mixed meal. When you ingest the different macronutrients together, this tends to slow down the rate that the stomach empties and levels out blood sugar levels. Also, diets high in fiber help to slow down digestion, and level out blood sugar levels.
Note that fructose-containing products should be avoided or minimized during exercise, because it is not readily used by the muscles during exercise. And while fructose has a low glycemic index, recent research indicates that eating too much of it may increase the rate of fat production and storage in the liver. So minimize ingesting processed fructose or high fructose corn syrup containing foods and drinks.
If you want to learn more about the glycemic index, please visit this page for a collection of articles on this subject.
[ Q ] When should I eat carbohydrate-rich foods?
What these studies have found is that it is important to maintain your body's glycogen (stored glucose) levels. This can be accomplished by taking in plentiful amounts of carbohydrates throughout the day, ranging from 55 to 60 percent of your total daily calories.
|CARBOHYDRATE NEEDS CALCULATOR|
Enter your daily caloric intake (in kcals) and press "Calculate".
It's best to consume a high-carbohydrate, moderate-protein, low-fat meal two to three hours prior to your training session to fuel your energy system. This meal timing depends on how your body digests the meal.
Some people may be able to eat their pre-exercise meal closer to exercise, as determined on an individual basis. Including complex carbohydrates in your meal tends to help your body load up with a good supply of glucose and recharge your body's glycogen system. This is recommended for pre-competition meals, too.
More important, foods high in complex carbohydrates do not usually cause a rapid rise in insulin levels, which is preferred for optimum physical performance. If insulin levels are too high during exercise, they will conflict with the function of the energy releasing hormone glucagon, which rises during exercise to release energy substrates for your exercising muscles.
| What Is Glucagon (Not Glycogen)?
Glucagon is a hormone produced by the pancreas that stimulates an increase in blood sugar levels, thus opposing the action of insulin.
Ingestion of carbohydrates after a workout depends on the sport in which you participate. In bodybuilding and powerlifting sports, there is a tremendous amount of emphasis put on maintaining muscle mass and timing meals around the growth hormone surges and potential insulin surges that occur right after high-intensity workouts.
Thus, it seems that ingesting beverages or nutrition bars containing high glycemic index carbohydrates approximately a half an hour to an hour immediately after a workout helps the body to restore its glycogen more quickly.
Recent studies have also shown that protein drinks, with carbohydrates, add to replenishing glycogen and also help stimulate muscle growth. Eating a well balanced high carbohydrate, moderate protein and low fat meal 30 minutes to an hour after workouts will also provide replenishment of glycogen.
However, most of these studies were performed with people who were not ingesting a carbohydrate drink immediately before and during resistance training. Just make sure to give your body time to recover, and "cool down". Also drink water before the post-exercise meal to maintain adequate hydration and good digestion.
When it comes to long-distance aerobic workouts, most of the research supports having a meal plentiful in lower glycemic index carbohydrates about a half hour to hour after major events and practice will help to replenish your glycogen stores. Keep in mind that as an endurance athlete you should already be ingesting a dilute, glucose containing beverage before, during and after the event or training.
Consistency of eating and supplementing correctly all day long is also vital to the performance nutrition program. One meal or snack event will not make up for not eating correctly the entire day.
Note that athletic events and practice lasting more than an hour and definitely over an hour and a half will put an athlete at risk of depleting glycogen levels or reducing levels to a point where it can adversely affect athletic performance.
Keep in mind that competitive athletes usually train for two or more hours a day. Therefore, both strength and endurance athletes need to make sure that they eat properly throughout the day, and drink a carbohydrate beverage during and after exercise sessions; especially if you notice that your energy levels decline during practice and events without a carbohydrate beverage.
I point this out for a few reasons. It has become a common practice for ingestion of carbohydrate beverages just before, during and after long distance events. But even long distance athletes sometimes do not do this during practice, which can lead to glycogen depletion or low glycogen levels and reduce performance.
Regarding the strength athlete, this is a common neglected area of sports nutrition. As strength athletes primarily use their glycogen stores for energy during practice and events, using the performance nutrition approach, it makes sense that these athletes should be ingesting carbohydrate beverages immediately before, during and after training and events.
While this was a novel concept, I first published it over a decade ago, other researchers have recently agreed with this approach. For example, in 2003, researchers at the Human Performance Laboratory, Midwestern State University, published a research report titled "Carbohydrate Supplementation and Resistance Training", which also advised athletes who are performing high-volume resistance training to ingest carbohydrate supplements before, during and immediately after resistance training.
Keep in mind that this is the ideal approach for maintaining maximum performance in competitive athletes. If your training is not as intensive or long in duration (less then 60 minutes), drinking a carbohydrate beverage may not be vital during exercise; but drinking water always is.
However, after exercise replenishing your glycogen system and dehydration is important for anybody undergoing exercise and physical activity. This can be accomplished with an energy drink, carbohydrate/protein containing sports supplements, or from your post-exercise meal.
As an aside, these performance nutrition approaches have applications for people how are in occupations that require a high level of physical activity.
[ Q ] Is it a good idea to drink carbohydrate beverages immediately before a workout or competition?
A: As I touched on in the previous answers, research studies have determined that sports events and training sessions that are going to be an hour or more in duration, ingestion of a high glycemic index beverage just before and during exercise will allow carbohydrates into the bloodstream quickly, providing exercising muscles with a readily available supply of energy.
Once you start to exercise, your muscles display what is called an insulin-independent uptake of nutrients. This means that exercising muscles can use glucose directly from the bloodstream, independent of insulin. This is important because during exercise, if there is a high amount of insulin released, it can cause the body to try to store glucose (also called dextrose).
This process conflicts with the function of glucagon, which rises during exercise to release glucose from the glycogen stores of the muscles to be used as energy.
Thus, if your pre-exercise eating is not right, high blood levels of insulin may result. In competitive athletes, high blood levels of insulin have been shown to cause reduced athletic performance. Therefore, when consuming a carbohydrate beverage prior to training or an event, start drinking it about fifteen minutes beforehand, so that your exercising muscles will offset the need for insulin increases.
In non-competitive training, if you have trouble timing your pre-exercise meal or energy drink intake, this effect will be less meaningful, but may explain why sometimes your body feels less energetic than you expect.
If you never ingested carbohydrate beverages before and during exercise it may take several days for your body to acclimate to this. Also, keep in mind that the beverages should be dilute, so they empty from the stomach rapidly.
The higher the concentration of solutes in a beverage, the longer it takes to empty from your stomach, which could ironically lead to dehydration. Gatorade was developed with this stomach emptying rate dynamic in mind and is a good beverage to start with.
The dilute, glucose containing type sports drinks are on the top of the list. Gatorade which contains glucose is an example, however it seems most ready to drink sports drinks contain high fructose corn syrup, sugar (sucrose) and sometimes maltodextrin (a short chain complex carbohydrate).
While these sports drinks will provide some benefit, the research demonstrates that glucose contain drinks are more quickly absorbed and used for energy in the body during exercise.
Alternatively, you can purchase glucose/dextrose powder from Bodybuilding.com and make your own dilute training and sports event drink. So during the competition season, it will be worth making an extra effort to use the glucose containing sports drinks, before, during and after exercise and events. On the off season it is less critical.
[ Q ] What if I have a hectic schedule and can't always eat right?
A: These are the ideal rules for maintaining maximum performance. If you have a hectic schedule, you may not be able to achieve optimum meal timing, so do your best.
Most people find that if they prepare a meal bag that they keep with them during the day, which contains a healthy fruit snack, a portable meal, nutrition bar, protein powder, energy beverage/bar, supplements and water; this increases the chances of following the performance nutrition plan. Also, keep in mind that these guidelines are for maintaining maximum performance.
If you slip up and eat too soon before training, you just may not have the best workout. However, try your best to stay on target the days before and day of competition for peak performance.
[ Q ] What happens to the glucose that my body doesn't use right away for energy?
A: Glucose that is not immediately used for energy is converted into a storage molecule called glycogen. Excess glucose can also be stored as fat, and serves as a building block for other compounds and tissue formation. Glucose is also used by the body to make glucosamine, which is needed for the synthesis of connective tissues. (Note, however, that excess glucose consumption does not result in extra connective tissue formation.)
Glucose, which can be used by all of the body's cells, is taken up at a much higher rate by muscle cells and will therefore be used very quickly to meet the energy demands of exercising muscle.
Fructose, a simple sugar, on the other hand, has a higher affinity to replenish liver glycogen and does not replenish muscle glycogen as well as glucose does. Giving athletes either glucose drinks, fructose drinks, placebo drinks, or complex carbohydrate drinks during exercise has shown that glucose has a significant performance-enhancing effect during oxidative sports.
Furthermore, ingested glucose has a greater muscle glycogen sparing effect (which means there is more muscle energy to exercise or compete longer) than fructose does. This is because the enzymes necessary to metabolize fructose and glucose in the muscles favor glucose.
[ Q ] How can I keep my glycogen supplies well replenished before an important endurance event?
A: A dietary technique called carbohydrate loading - also called carbohydrate super-compensation - can super-load your muscle glycogen stores. Researchers found that this could be accomplished in a few ways. Using the traditional technique, carbohydrate consumption is reduced for a few days, which actually depletes glycogen stores.
Timing is important and this glycogen-depletion phase should be done five to six days before an important event. A two- to three-day glycogen-depletion phase would include reducing carbohydrate levels to about 10 percent of your total daily calories. Obviously, during that period, exercise performance will be impaired.
This period of glycogen depletion is then followed by a high carbohydrate diet - up to 90 percent carbohydrates for three days to build up glycogen levels to much higher levels than would normally be attained. However, many athletes find it difficult to follow this six-day traditional method of glycogen depletion and don't wish to experience reduced performance during the glycogen-depletion phase.
To compensate for this, researchers have come up with other ways to effectively deplete and load the glycogen system by modifying the diet less drastically than the traditional method.
One of these modified methods of glycogen loading recommends keeping training levels high, while maintaining a macronutrient intake over five or six meals at approximately 15 percent fat, 30 percent protein, and 55 percent carbohydrates for four days. After four days of this phase, two days before your competition, begin glycogen loading by ingesting a plentiful amount of carbohydrates.
The diet you should follow during this phase should provide 15 percent fat, 15 percent protein, and 70 percent carbohydrates. Stress the intake of carbohydrates that have low to medium glycemic indexes up to a rating of 49 percent, and restrict the intake of high glycemic index carbohydrate beverages to immediately before, during, and after exercise.
[ Q ] Are there any side effects to carbohydrate loading?
A: Some athletes may experience some minor side effects from carbohydrate loading. These include muscle stiffness, which may result in muscle cramping and premature fatigue. During the depletion phase of the traditional carbohydrate-loading technique, some individuals experience fatigue and dizziness. Therefore, you should not perform any exercise that can result in injury during the traditional glycogen-depletion technique.
Athletes interested in using carbohydrate loading should do so a month before a major event to see how their body responds to it. It is interesting to note that every gram of glycogen in the body is stored with about 4 g of water. This explains the mystery behind many of the fast weight-loss diets, which are low in calories and low in carbohydrates.
Individuals will lose several pounds of water weight, as they deplete their glycogen system. Note that it is important to pay extra attention to being properly hydrated when using carbohydrate loading. Finally, scientists have determined that the body becomes non-responsive if you try to carbohydrate load too many times during the season.
Restrict it to three or four or maybe up to five times during any particular athletic season. This means you should use carbohydrate loading strategically to boost your endurance performance for special competitions.
[ Q ] Are there dietary supplements that help with carbohydrate loading?
A: Taking extra amounts of certain B vitamins (B3 and B6) a couple of days before you begin the glycogen-depletion phase, and then on the first day of the glycogen-depletion phase can help stimulate the rate at which glycogen is depleted from your body. Then, during the glycogen-loading phase, take in extra chromium (up to 600 mcg a day) and double your normal amounts of vitamin C and beta-carotene to help increase the rate at with the muscles store glycogen.
Utilizing carbohydrate sports drinks can help maximize your body's glycogen content. Choose drinks that contain only glucose for use before, during, and after exercise for best results. In addition, there is some indication that ingestion of 1 to 3 grams per day of the amino acid L-glutamine can help with the glycogen-loading phase.
It's also important to ingest either a complex carbohydrate food or beverage that contains approximately 400 to 600 calories per serving in the morning and an hour before bedtime to prevent muscle glycogen depletion. It can also contain protein, but should be low in fat content.
Keep in mind that carbohydrate loading is no panacea or magic bullet to make up for poor training and nutrition. However, as part of a total ergogenic sports nutrition program, it can help give you a competitive edge.
| What Does Ergogenic Mean?
"Performance-enhancing", or "muscle-gaining capacity building", especially by eliminating the symptoms of fatigue.
[ Q ] Is fiber important in an athlete's diet?
A: Yes. Fiber is important in all diets. Fiber helps promote normal digestive system function and also digestive system health. It helps regulate digestion too. Fiber rich foods also contain essential nutrients and phytonutrients that help protect the body and promote good body function.
Adequate fiber intake is important for circulatory system health, as fiber helps to keep cholesterol in check. In addition, many of the phyto-nutrients found in whole grain fibers are beneficial for the circulatory system.
You can refer to the Adobe PDF file from the USDA database (see below), which is arranged to list high to low fiber foods to get an idea what foods to include in your performance nutrition diet for adequate fiber intake. Fibers occur in various amounts in plant foods as fruits and vegetables, including grains and beans.
If you find that your diet is still low in fiber after your best attempt to increase fiber from foods sources, you can include a fiber supplement in to your nutrition program to help increase the total daily fiber content.
I've included here a PDF file of USDA-categorized fiber foods (Adobe Reader file, 244 KB), sorted by high-to-low fiber content.
To View Or Download The USDA Fiber PDF, Click Here.
Listen to the podcast for more details:
|DAN GASTELU EXPLAINS...|
- RDA - nutrient intake levels for most healthy persons.
- Adequate Intake (AI) - intake levels for nutrients when an RDA cannot be determined.
- Tolerable Upper Intake Level (UL) - nutrient ceiling for normal, healthy persons.
- Estimated Average Requirement (EAR) - nutrient intake levels that meet the needs of only half of healthy persons.
The Dietary Reference Intake (DRI) guidelines recommend an average intake of 38 grams of total fiber a day for men and 25 grams of total fiber a day for women. This level of fiber intake would be considered a minimum to maintain. Higher fiber intake can add additional health benefits.
| RDAs Incorporated Into DRIs.
Recommended Dietary Allowances (RDAs), established in 1941 and updated regularly, are the intake levels of essential nutrients deemed adequate by the U.S. Government to meet the dietary needs of healthy persons.
In 1995, however, the traditional RDAs were replaced and expanded into Dietary Reference Intakes (DRIs). DRIs have four parts:
DRIs are adjusted for many factors, including age and gender, to take into account a variety of lifestyle settings.
When you start reading the nutrition facts information on foods, you will notice that most processed foods are very low in fiber content. This is one of many reasons why eating more fresh whole foods (fruits and vegetables) and whole grain products is important and how eating less snack foods and process foods will make your nutrition program healthier.
To find and learn more about taking action toward creating a high fiber food diet, visit a health food store to see a selection of wholesome, natural foods that are rich in fiber and essential nutrients. People in health food stores are well trained, so ask them to help you select high fiber foods.
To View Top-Selling Fiber Products, Click Here.
Here is a high fiber intake tip if you are on the run, with little time to prepare foods to carry with your or to eat at home. Try eating more high fiber, whole grain bread. This can be a great way to increase your dietary fiber content, and also provide a good supply of complex carbohydrates and protein.
To Read More About Fiber, Click Here.
Choose whole grain breads that are organic and low fat. You will find that they are flavorful, can be eaten plan, and travel well and better then eating processed snack foods. You can also prepare high fiber whole grain pasta, and carry this around as a portable meal and snack to keep you well nourished and energized throughout the day. Just make sure you are drinking plenty of water each day to keep well hydrated.
[ Q ] What is pyruvate and how does it compare with carbohydrates?
A: Pyruvate is a byproduct of glucose metabolism, which is available in supplemental form. Early research on pyruvate's use in laboratory animals established its short-term safety. These studies indicated that pyruvate-under controlled-diet conditions-enhances endurance and has a beneficial effect on weight loss.
This early research was followed by more studies, this time on humans, which were conducted by R. T. Stanko and coworkers. Their first studies focused on determining the ability of pyruvate supplementation to enhance endurance performance.
One such study found a 20 percent improvement in exercising arm endurance. One group of subjects had substituted 25 g of pyruvate and 75 g of dihydroxyacetone (not available as a dietary supplement) for an equal amount of carbohydrate for seven days. Another group served as a control.
- First, the dosages used by Stanko were very high when compared with the 500 mg to 5 g dosages recommended on the labels of most pyruvate supplement products.
- Second, there were minor side effects observed in the studies, including gastrointestinal distress.
- Third, these studies were conducted on a small number of individuals, whose level of athletic conditioning was not reported, in a laboratory setting under medical supervision.
- Fourth, pyruvate is typically available as a sodium or a calcium salt. This means the ingestion of these higher experimental dosages could cause mineral overload of calcium and sodium.
- Fifth, it's impossible to determine if the possible beneficial effects were due to pyruvate, because three times the amount of dihydroxyacetone was also ingested.
- Sixth, at this time, I cannot recommend the unsupervised use of dihydroxyacetone in foods or supplements. This is because dihydroxyacetone does not have a history of use in ingestible products, and its safety as such is not confirmed.
Researchers noted that muscle glycogen stores were higher in the pyruvate/dihydroxyacetone group at the beginning of exercise, and the same between the two groups at the end of exercise. This observation suggests that the increased stores of muscle glycogen were able to provide additional energy during exercise, which resulted in the 20 percent increase in endurance.
In another study by Stanko, the effects of ingestion of the 75 g of dihydroxyacetone and 25 g of pyruvate, were measured with exercising individuals after consuming a high carbohydrate diet. The pyruvate/dihydroxyacetone group again experienced an increase in endurance.
Points To Note
It's important to note a few practical points about these studies.
Until more research is conducted on pyruvate's role in promoting oxidative endurance, this supplement should be used on a limited, optional basis, and best used under the supervision of a health-care professional.
For More Information
You can subscribe to my Awesome Muscles Podcast Series to hear about the latest and greatest information about training and nutrition for sports, fitness and health. This is an online podcast seminar series, which you can also listen to online or download on to your computer and/or iPod (mp3 player).
| What Is A Podcast?
Podcasting is a collection of technologies for automatically distributing audio and video programs over the Internet via a publish and subscribe model.
Podcasting enables independent producers to create self-published, syndicated "radio shows," and gives broadcast radio or television programs a new distribution method.
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Notice and Disclaimer: This sports nutrition guide and related articles and seminar series are not intended for use as a substitute for consultation with a qualified medical practitioner. If you have symptoms of any illness or injury, it is essential that you see your doctor immediately for proper treatment.
This information is for education and entertainment purposes only. We strongly recommend that you consult a physician before beginning any exercise program and nutrition program. You should understand that participating in any exercise program can result in physical injury and you agree to do so at your risk.