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

2. Introduction to exercise metabolism and bioenergetics

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. 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.

14. 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

15. 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.

16. 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.

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

18. 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.

19. 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.

20. 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.

21. 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.

22. 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.

23. ATP as Energy

24. 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 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.

25. 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 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.

26. 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.

27. 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.

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

29. 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

30. 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.

31. 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.

32. 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.

33. 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.

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

35. 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

36. 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.

37. 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