SCI Energy Systems & Exercise Physiology 2 — Questions and Answers
Question 1: Excess Post-exercise Oxygen Consumption (EPOC) refers to:
- Oxygen consumed during warm-up before class
- Elevated oxygen uptake after exercise to restore homeostasis (Correct answer)
- Maximum oxygen used during the peak of exercise
- Oxygen deficit at the very start of exercise
Correct answer: Elevated oxygen uptake after exercise to restore homeostasis
EPOC is the elevated oxygen consumption that continues after exercise ends, used to restore ATP, replenish phosphocreatine, clear lactate, and return the body to homeostasis.
Question 2: The Krebs cycle (citric acid cycle), a key stage of aerobic metabolism, takes place in the:
- Cell nucleus
- Cytoplasm
- Mitochondrial matrix (Correct answer)
- Sarcoplasmic reticulum
Correct answer: Mitochondrial matrix
The Krebs cycle occurs in the mitochondrial matrix, where acetyl-CoA is oxidized to produce NADH, FADH2, and a small amount of ATP.
Question 3: Regular aerobic training improves the body's ability to use fat as fuel primarily by:
- Decreasing the number of mitochondria in muscle fibers
- Increasing mitochondrial density and fat-oxidizing enzyme activity (Correct answer)
- Shifting fuel use entirely to carbohydrates during all intensities
- Reducing capillary density in working muscles
Correct answer: Increasing mitochondrial density and fat-oxidizing enzyme activity
Aerobic training stimulates mitochondrial biogenesis and upregulates fat-oxidizing enzymes, enabling muscles to burn fat more efficiently at any given intensity.
Question 4: During steady-state aerobic exercise, a rider's heart rate will typically:
- Continue to rise steadily throughout the session
- Plateau and remain relatively constant (Correct answer)
- Drop below resting levels within 10 minutes
- Become irregular and unpredictable
Correct answer: Plateau and remain relatively constant
During steady-state exercise, oxygen supply meets demand, and heart rate stabilizes at a level appropriate for that workload.
Question 5: Which muscle fiber type is most resistant to fatigue and is preferentially recruited during low-intensity, prolonged cycling?
- Type IIx (fast-twitch glycolytic)
- Type IIa (fast-twitch oxidative-glycolytic)
- Type I (slow-twitch oxidative) (Correct answer)
- Type III (intermediate-twitch)
Correct answer: Type I (slow-twitch oxidative)
Type I (slow-twitch) fibers are highly oxidative, rich in mitochondria and capillaries, fatigue-resistant, and are the first fibers recruited during low-intensity aerobic exercise.
Question 6: During high-intensity anaerobic cycling efforts, the primary fuel source is:
- Free fatty acids
- Amino acids from muscle protein
- Muscle glycogen (glucose) (Correct answer)
- Phospholipids
Correct answer: Muscle glycogen (glucose)
Muscle glycogen is rapidly broken down via glycolysis to fuel high-intensity anaerobic exercise, producing ATP quickly without oxygen.
Question 7: A respiratory exchange ratio (RER) of 1.0 indicates that the body is primarily burning:
- Fat
- Protein
- Carbohydrates (Correct answer)
- A 50/50 mix of fat and carbohydrate
Correct answer: Carbohydrates
An RER of 1.0 means CO2 produced equals O2 consumed, which indicates carbohydrates are the primary fuel since carbohydrate oxidation yields a 1:1 CO2:O2 ratio.
SCI Energy Systems & Exercise Physiology 2
Excess Post-exercise Oxygen Consumption (EPOC) refers to: