Chapter 2 Flashcards
Name at least three forms of energy
Chemical Energy, Mechanical Energy, Heat Energy
Examples of energy transfer: Carbs → ATP for muscle contraction (mechanical), ATP breakdown → heat energy for body temperature regulation.
Is ATP ever used up completely by exercising muscle?
No, ATP is never fully depleted
A small reduction in ATP can impair muscle function, leading to mechanisms that rapidly regenerate ATP.
How does the muscle respond to reduced ATP concentrations?
Activates energy systems to replenish ATP:
* Creatine phosphate System
* Anaerobic Glycolysis
* Aerobic System
What is the most commonly used unit of measure for energy in nutrition?
Kilocalorie (kcal)
In the SI system, joules (J) are the standard measure of energy.
How is the energy content of food determined?
Using a bomb calorimeter
Measures the heat released when food is burned.
What is the energy content of carbohydrates?
4 kcal/g
What is the energy content of proteins?
4 kcal/g
What is the energy content of fats?
9 kcal/g
What is the energy content of alcohol?
7 kcal/g
How is energy expenditure measured by direct calorimetry?
By assessing heat production in a calorimeter chamber
Measures total energy expenditure based on heat produced by the body.
What is indirect calorimetry?
Estimates energy expenditure by measuring VO₂ and VCO₂
Based on the principle that energy metabolism requires oxygen and produces CO₂.
What does RER stand for?
Respiratory Exchange Ratio
What does an RER value of 0.70 indicate?
Predominantly fat oxidation
What does an RER value of 1.00 or higher indicate?
Predominantly carbohydrate oxidation or anaerobic metabolism
What is the Doubly Labeled Water Method (DLW)?
Measures CO₂ production using water labeled with stable isotopes
Considered the gold standard for measuring free-living energy expenditure.
What is the energy balance equation?
If Energy In > Energy Out → Weight gain; If Energy In < Energy Out → Weight loss
What are the three components of ‘energy out’?
Resting Metabolic Rate (RMR), Thermic Effect of Food (TEF), Physical Activity Energy Expenditure (PAEE)
What percentage of daily energy expenditure does RMR account for?
~70%
What is Resting Metabolic Rate (RMR)?
The amount of energy expended at rest to sustain basic physiological functions
Which factors influence RMR?
Body Composition, Age, Sex, Genetics, Hormones, Temperature & Climate, Fasting/Dieting, Exercise & Training
What has the greatest influence on RMR?
Lean body mass (muscle mass)
How accurate are prediction equations for estimating RMR?
Standard prediction equations can be off by ±10-20%
More precise methods include indirect calorimetry.
What activity factor is used for a sedentary individual?
1.2
What activity factor is used for a professional rugby player?
2.5 - 3.0+
What is the most accurate way of measuring total daily energy expenditure (TDEE)?
Doubly Labeled Water (DLW)
What is the most practical method for measuring TDEE in a university setting?
Indirect Calorimetry and Prediction Equations + Activity Logs
What is the estimated kcal needs for a soccer player in practice for 2-3 hours a day?
~3,500 - 4,500 kcal/day
What are the energy factor estimates for an athlete recovering from a broken leg?
1.2 - 1.3
What are the estimated kcal needs for an athlete training for an Ironman?
~5,000 - 8,000 kcal/day
