ISSA SN Chapter 3: Carbohydrates: The Ultimate Performance Food

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Chapter Goals:

  • Discuss and describe the main terms that relate to the carbohydrates
  • Know the many forms of carbs.
  • Be informed regarding the glycemic index and glycemic load.
  • Find how carbs affect athletic performance and health.


Carbs are a macronutrient that is surrounded by a lot of controversy and bad thoughts. A lot relies on the relationship between weight loss and maintaining weight. Many will label all carbs as bad.

All in all, this is an important macronutrient that is needed for optimal performance and function. People require most of their food intake to come from carbohydrates. Usually, this range is between 45 and 65 percent of total daily calories.

Carbohydrates and Athletes

Carbs will be used for high energy production and the athlete’s peak performance. Many athletes will take in 55 – 60% of their total calories from carbs. It is high because it is the primary nutrient for energy. This percentage may or may not vary greatly on a day to day basis. 

Timing the consumption of carbs through food and also through beverages can be a big deal also. This can help you to keep your energy levels high during longer workouts or competitions. This will act to spare the glycogen reserves when taken during the activity.

Typically, we try to do this in activities longer than 45 minutes. When the timing is right, it does not cause too much of an increase in insulin levels. This can cause a conflict between the function of the glucagon and our energy production. 

When the body is out of its stores of glycogen, we are forced to use our stores of fatty acids as the main energy source. This can cause a significant decline in the quality of our physical activity. The use of proteins and amino acids may also increase under these conditions, which is more of a last resort, as stated earlier. For endurance athletes, it is termed as “hitting the wall.” 

Athletic Significance of Carbohydrates:

  • Carbs are the high energy sources of fuel for the muscles and other tissues in the body.
  • Glucose is the prime carb within our diet and is used for energy.
  • Glucose is the main energy source for the brain and the nervous system as a whole.
  • Complex carbs need to be eaten more so than simple carbs. 
  • Ingestion of carbs before, during, and after exercising should be times appropriate.
  • The body will store glucose as glycogen for use later.
  • Glucose has structural roles and is used for producing glucosamine to form other connective tissues. 

Types of Carbohydrates

We have several different types of carbs that are taken in through the diet. The categories these are in will be based on the sugar molecules attached. We have mono, di, oligo, and polysaccharides. 

Simple Carbohydrates

Monosaccharides are carbs that are made up of one unit of sugar. Some examples would be glucose and fructose. 

Disaccharides are carbs that are made up of just two sugar units. These are carbs like sucrose and maltose. 

Sugar is simply a catchall term used for the many types of carbs. Actual table sugar is actually sucrose, but sugar may also refer to glucose and fructose. 

The main monosaccharides are going to be glucose and fructose. 

All sugar causes a change in the blood sugar level, which is to be kept at a mostly constate level with the use of hormones and other bodily functions. 

Complex Carbohydrates

Oligosaccharides are complex carbs that are made up of between 3 and 10 units of sugar. Some examples would include raffinose and stachyose. These can sometimes be called polysaccharides. 

Polysaccharides are the complex carbs having more than the 10 sugar units in the previous complex carb. Some examples of these would be starches and amylopectin. 

Fiber is a complex carb that is not digestible or absorbed within the small intestine. Fiber is seen as roughage or a nonstarchy polypeptide. Total fiber is the sum of both functional fiber and dietary fiber.

Dietary fiber comprises nondigestible carbs and lignin that are intrinsic and intact in plants. 

Soluble fiber will dissolve in water to form a thick gel within the stomach. It breaks down in the large intestine due to bacteria and does provide a small number of calories in the sense of around 2 calories per gram. This interferes with the absorption of dietary fat and cholesterol. So, it can be somewhat healthy to take in a good amount of these soluble fibers. 

Insoluble fiber does not dissolve in water or form that gel like soluble fiber. So, this will not be a source of any calories; instead, it acts as bulk for our stool. It works to improve the movement of food through the digestive system. 

Both soluble and insoluble fiber can function to fulfill our feelings of hunger.

Functional fiber is made of isolated nondigestible carbs with beneficial physiological effects in humans. These fibers may be isolated or extracted using chemicals, enzymes, or other steps. 

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Total fiber is the sum of dietary fiber and functional fiber. 

Overview of Some Common Dietary and Functional Fibers

Cellulose is a polysaccharide that is not digestible and is made up of many glucose molecules together formed with a special bond. This is the main structural compound of the cell walls in plants.

Chitin is one of the more common polymers and it is natural. It is found in animals known as arthropods most often. 

Chitosan is chemically known as poly-D-glucosamine. It is found naturally and is made commercially from chitin with a simple process. It is sometimes used in dietary supplements for some binding to fat.

Beta-Glucans are the polysaccharides of the branched glucose. 

Fructo-oligosaccharides are the polymers of glucose and fructose. 

Gums are made up of very diverse polysaccharides. They are derived from seeds for application commercially. 

Hemicelluloses are groups of polysaccharides that we find inside plant walls. 

Pectins are the last to talk about. These are found in many fruits and berries’ cell walls and intracellular tissues. They comprise galacturonic acid units with rhamnose throughout the linear chains. 

Digestion of Carbohydrates

Chemical digestion begins with the mouth and is done with enzymes found in the saliva and then continues within the intestines, where our digestive juices break down the long chains of glucose, making up carbs bigger than monosaccharides. Max absorption of the carbs happens when the stomach empties the contents into the intestines. The rest of the nutrients in the meal also play a role in the absorption rate. 

About the Glycemic Index

This is used to group the carbs into groups relating to their effect on the blood sugar level. When some food with carbs is eaten and then digested, it is taken in through the bloodstream and a rise occurs in the blood sugar level. A rise will also join this rise in the amount of insulin. The rise and fall can be either rapid or slow. 

Since all carbs have different absorption rates, they affect blood glucose levels differently. Researchers devised a way to rate their effect on the blood. 

Numerical values are given to the foods, with the reference being glucose at a value of 100. So, everything is compared to that. Most of the foods will be below this value of 100, with some exceptions.

Glycemic Load

The glycemic index looks at how fast a food raises blood sugar levels, and the GL is a calculation that considers the number of carbs in the ingested food. So, how much of the food matters besides the glycemic index? 

Carbohydrates in the Body-Glucose and Glycogen

This is like the starch in plants and it is made up of chains of glucose units. Glycogen and starch both differ in their structure. Starch is found in plants, while glycogen is found in animals. The total glycogen supply, though in one person, is around 1,800 to 2,600 calories. The body will constantly store and release glucose as glycogen to maintain our blood sugar levels. 

Glycogen is found in all of our cells, but we contain the most in our muscles and liver cells. So, these two places will be reservoirs for glycogen for the body. The brain will use around 400 calories of glucose from the liver’s glycogen store daily. 

Glycogen is stored together with water. Every ounce of glycogen has about 3 ounces of water with it. 

For athletes, some recommendations for management are:

  • Keep the liver and muscle glycogen stores full.
  • Put in some daily nutrition program that works to encourage replenishment of the glycogen stores and works to spare our utilization of those stores. 
  • Maximize glycogen stores using loading schemes for sports relating to endurance and long competition days in other sports.

Carbohydrates for Increased Athletic Performance

To keep glycogen stores at the right levels, we should consider it on a day to day basis and before our events. We should devote our thought to some important factors:

  • Maintenance of cab balances every meal of every day.
  • Increases in the intake of carbs before events and training.
  • Selective ingestion of carbs while exercising.
  • Ingesting carbs following exercise and sometimes methodically building up glycogen stores before an event with techniques like carb loading.
  • High intakes of complex carbs, with large levels of simple carbs in the morning, during exercise, and right after exercise to quickly replenish any depletions in glycogen stores. 
ISSA SN Chapter 3: Carbohydrates: The Ultimate Performance Food 4
ISSA SN Chapter 3: Carbohydrates: The Ultimate Performance Food 5
ISSA SN Chapter 3: Carbohydrates: The Ultimate Performance Food 6

Tyler Read - Certified Personal Trainer with PTPioneer

Tyler Read

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