Module 17: Exercise Metabolism and Bioenergetics Fitness Foundations Module 17: Exercise Metabolism and Bioenergetics

Introduction to exercise metabolism and bioenergetics

Bioenergetics and Metabolism Bioenergetics―the study of how energy is transformed through biochemical reactions in the human body Metabolism―the chemical reactions that occur in the body to maintain itself Discuss bioenergetics and metabolism and how they apply to personal training and clients.

Bioenergetics and Metabolism Exercise Metabolism― the examination of bioenergetics relating to the unique physiologic changes and demands place on the body during exercise. Discuss what exercise metabolism and why it is important for us to understand.

Supply of Energy Exercise places demanding requirements to supply energy and remove metabolic by-products Food we eat provides energy, but has to be converted into units called substrates: Carbohydrates Proteins Fats Introduce the idea of the substrates commonly referred to as Macro Nutrients.

Supply of Energy The energy in the substrate molecules is chemically released in cells and stored in a high-energy compound called ATP Discuss the importance of ATP as being the energy currency of the body.

Fuel for Energy Metabolism Food provides energy to sustain life and support physical activity, but first has to be broken down by the digestive system into substrates. Introduce the importance of food for energy and exercise.

Carbohydrates Provide body with fuel and energy for all daily activities including exercise Lack of carbohydrates in diet can cause: Fatigue Poor mental function Lack of endurance and stamina Discuss the importance of carbohydrates in regards to exercise and why it is important to have in a diet.

Composition of Carbohydrates Organic compounds of carbon, hydrogen, and oxygen, which include starches, cellulose, and sugars Important source of energy All carbohydrates are eventually broken down in the body to glucose, a simple sugar Discuss where carbohydrates can be found. Introduce the concept of glucose and why it is important as a fuel for the body.

Glucose A simple sugar manufactured by the body from carbohydrates, fat, and to a lesser extent protein, which serves as the body's main source of fuel Glucose is absorbed and transported in the blood Circulates in blood until it enters cells with the aid of insulin Either used or stored as energy Discuss how glucose is utilized in the body as a source of fuel. Discuss the importance of glucose to the brain.

Glycogen The complex carbohydrate molecule used to store carbohydrates in the liver and muscle cells When carbohydrate energy is needed, glycogen is converted into glucose for use by the muscle cells Stored in the liver and muscle cells Discuss the importance of glycogen as it relates to the storage of carbohydrates and energy that will be used by the body.

Fat One of the three main classes of foods and a source of energy in the body Helps the body use some vitamins Keeps the skin healthy Serves as energy stores for the body Discuss the importance of fat in the diet. Ensure that the students understand that it is unhealthy to avoid all fats.

Fat Two types of fats in food, saturated and unsaturated Benefit of fat as a fuel source is that most people have inexhaustible supply of fat: Can be broken down into triglycerides Used for energy during prolonged physical activity or exercise Discuss the importance of fat for exercise and working out.

Fats Saturated Fats Solid at room temperature Derived from animal products Some plant sources – coconut palm Raise LDL Cholesterol (bad Cholesterol) Unsaturated Fats Liquid at room temperature Derived from vegetables & plants (olive oil, nuts, peanut oil, canola oil) Lowers LDL and maintains HDL

Triglycerides The chemical or substrate form in which most fat exists in food as well as in the body. Formed from fats eaten in foods or made in the body from other energy sources such as carbohydrates When calories are not immediately needed they are converted to triglycerides Transported to fat cells where they are stored Discuss the importance of triglycerides and how they are used within the body.

Protein Amino acids linked by peptide bonds Consist of carbon, hydrogen, nitrogen, oxygen, and usually sulfur, and have several essential biologic compounds Rarely supplies much energy during exercise Discuss the importance of protein within the body. Express that protein should not be a regular source of energy within the body.

Protein Is sometimes ignored as a significant fuel for energy metabolism Becomes a significant source of fuel in starvation situations

Gluconeogenesis The formation of glucose from noncarbohydrate sources, such as amino acids During negative energy balance, amino acids are used to assist in energy production Discuss negative energy balance as occurring when more energy is being expended than is being ingested.

Energy and Mechanical Work Forms of exercise can be defined by: Intensity Duration Understanding this relationship will help to determine which energy system one is using at different intensities and durations of exercise Discuss the use of energy during work. Utilize the chart to show that the longer someone exercises the less intense they will be able to work.

Energy and Muscle Contraction Energy is used to form the myosin-actin cross-bridges that facilitate muscle contraction At these cross-bridges is an enzyme that separates a phosphate from the ATP, releasing energy Review sliding filament theory and apply it to this slide. This is an important concept to understand so the students can grasp how muscles contract.

Energy Systems and Work Energy Systems in the Body Stored Adenosine Triphosphate System(Stored ATP)―energy storage and transfer unit within the cells of the body Adenosine Diphosphate (ADP)―a high-energy compound occurring in all cells from which adenosine triphosphate (ATP) is formed Discuss ATP and ADP and their interactions with eachother.

Adenosine Triphosphate When the enzyme ATPase combines with an ATP molecule, it: Splits the last phosphate group away Releases large amount of free energy What remains is ADP and an inorganic phosphate molecule (Pi) Discuss this with the class. Make sure they have a grasp of this concept as it is the base for which the next several slides build upon. Let this serve as an introduction to the energy pathways.

ATP as Energy

ATP-PC System A phosphate is transferred from another high-energy molecule called phosphocreatine to an ADP molecule Fast, High Energy, without oxygen (anaerobic) Utilized for quick intense activities lasting 10-15 seconds in duration Introduce the ATP-PC energy system. Give examples of activities that will utilize this system. Have the class come up with examples as well.

Anaerobic Glycolysis System Anaerobic means of producing ATP Through chemical breakdown of glucose A process referred to as anaerobic glycolysis This system will be utilized for events lasting 30-50 seconds in duration Introduce the Glycolytic energy system. Give examples of activities that will utilize this system. Have the class come up with examples as well.

Oxidative System Most complex of energy systems Utilized for events lasting longer than 50 seconds Uses substrates with the aid of oxygen to generate ATP With Oxygen (aerobic) Three oxidative or aerobic systems: Aerobic glycolysis The Krebs cycle The electron transport chain (ETC) Introduce the Oxidative energy system. Give examples of activities that will utilize this system. Have the class come up with examples as well.

Energy During Exercise Most important factors regulating energy utilization during exercise is: Intensity Duration Intensity and duration of exercise are inversely related As duration of exercise increases (up to approximately 2 minutes), the primary source of energy comes from glucose With longer exercise the main fuel source will switch to fats Discuss the different fuel sources during exercise. Emphasize that many different fuel sources are used at the same time but depending on the intensity and duration of the exercise one fuel source will be utilized more than the others.

Energy During Exercise Discuss the previous slide in regards to the chart to demonstrate what the different energy system usages look like during exercise.

Steady-State Exercise Bioenergetics of exercise can be indirectly measured in a laboratory using: Treadmill Cycle ergometer Rowing ergometer Cross-country ski simulator Swimming flume Discuss exercise testing and steady-state exercise

Steady-State Exercise During these modes of exercise, the concentrations of oxygen and carbon dioxide and volume of expired air are measured Other physiologic functions can be measured: Heart rate Blood pressure Exercise load Work output Discuss the oxygen and carbon dioxide consumption during steady-state exercise and how it applies to health and testing.

Steady-State Exercise When client finishes exercise: Energy demands fall back to baseline quickly Oxygen consumption remains elevated for a short period to keep generating ATP aerobically Excess postexercise oxygen consumption (EPOC) ―the state in which the body’s metabolism is elevated after exercise Discuss what is tested at the end of steady-state exercise testing.

Steady-State Exercise Discuss this chart in reference to the previous slides. Allow it to help illustrate what was just discussed. Apply it to the different energy systems that were previously discussed.

Intermittent Work During intermittent exercise: Client will experience increase in intensity Followed by recovery The work to rest ratio tends to be short It will take approximately 90 seconds to replenish the ATP-PC system. Discuss the importance of recovery for athletes and training that with intermittent work. Discuss how this applies to the different energy systems. Discuss the importance of this to the application of athletes and sports.

Estimating Fuel Contribution Discuss the RQ and how it applies to estimating energy usage and the source of energy.

Fat-Burning Zone Myth Low-Intensity Exercise 20 minutes of walking at 3.0 mph, RQ of .80 67% from fats 33% from carbs 4.8 calories per minute 3.2 calories from fat 1.6 from carbs 64 calories from fat 32 calories from carbs Discuss this example of someone in the “fat-burning” zone

Fat-Burning Zone Myth High-Intensity Exercise 20 minutes of walking at 6.0 mph, RQ of .86 46% from fats 54% from carbs 9.75 calories per minute 4.48 calories from fat 5.2 from carbs 90 calories from fat 104 calories from carbs Discuss the higher intensity outside of the “fat-burning” zone. Ensure the students understand that higher intensities may burn a lower percentage of fats but more calories from fat because of the energy that is required.

Fat-Burning Zone Myth Some marketing departments of exercise equipment have misinterpreted concept The inaccuracy is that people burn more fat at lower-intensity exercise because such easy work does not require getting energy quickly from carbohydrates The concept is logical but the science is flawed Discuss the fat burning zone myth