Chapter 3: Exercise Metabolism and Bioenergetics
Nutrition, Performance, and Recovery
Putting Value into the Diet
There are a variety of components of the average daily diet that contribute to an effective nutrition strategy for improving exercise performance including optimizing your macronutrient, micronutrient, and fluid intake and timing of consumption to help provide a more effective and individualized dietary intake pattern.
Macronutrients
Energy-yielding Macronutrients include the nutrients that many people have at least heard of before:
- Carbohydrates
- Proteins
- Lipids (fats)
Carbohydrates
Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen atoms. Include our simple sugars such as glucose and fructose and complex sugars such as starch, glycogen, and cellulose. The complex sugars are also called polysaccharides and are made of multiple monosaccharide molecules. Polysaccharides serve as energy storage (e.g., starch and glycogen) and as structural components (e.g., chitin in insects and cellulose in plants).
Our simple sugars can be digested and absorbed quickly to provide energy via ATP to the cells during higher intensity activity. While our complex carbohydrates require a bit more time for digestion and absorption and can provide the body with a longer, slower release of energy over time.
Protein
Much of the body is made of protein, and these proteins take on a myriad of forms. They represent cell signaling receptors, signaling molecules, structural members, enzymes, intracellular trafficking components, extracellular matrix scaffolds, ion pumps, ion channels, oxygen and CO2 transporters (hemoglobin). That is not even the complete list! There is protein in bones (collagen), muscles, and tendons; the hemoglobin that transports oxygen; and enzymes that catalyze all biochemical reactions. Protein is also used for growth and repair. Amid all these necessary functions, proteins also hold the potential to serve as a metabolic fuel source. Proteins are not stored for later use, so excess proteins must be converted into glucose or triglycerides, and used to supply energy or build energy reserves. Although the body can synthesize proteins from amino acids, food is an important source of those amino acids, especially because humans cannot synthesize all of the 20 amino acids used to build proteins.
Lipids
Fats (or triglycerides) within the body are ingested as food or synthesized by adipocytes or hepatocytes from carbohydrate precursors (Figure). Lipid metabolism entails the oxidation of fatty acids to either generate energy or synthesize new lipids from smaller constituent molecules. Lipid metabolism is associated with carbohydrate metabolism, as products of glucose (such as acetyl CoA) can be converted into lipids.
Dietary Strategies for Performance
There are several strategies that have been used to help improve an athlete’s performance during different activities. The most effective use of these strategies will depe