ACE Exercise Physiology 2 — Questions and Answers
Question 1: Which of the following is the PRIMARY determinant of cardiac output?
- Blood pressure × total peripheral resistance
- Heart rate × stroke volume (Correct answer)
- Respiratory rate × tidal volume
- Hemoglobin concentration × oxygen saturation
Correct answer: Heart rate × stroke volume
Cardiac output (Q) is calculated as heart rate multiplied by stroke volume, representing the total volume of blood pumped by the heart per minute.
Question 2: During aerobic exercise, which muscle fiber type is recruited FIRST?
- Type IIx (fast-twitch glycolytic)
- Type IIa (fast-twitch oxidative-glycolytic)
- Type I (slow-twitch oxidative) (Correct answer)
- Type III (intermediate)
Correct answer: Type I (slow-twitch oxidative)
According to the size principle, the nervous system recruits smaller, low-threshold Type I (slow-twitch) motor units first before engaging faster, higher-threshold fibers.
Question 3: What is the Fick equation used to calculate?
- Maximum lung capacity
- Oxygen consumption (VO2) (Correct answer)
- Respiratory exchange ratio
- Blood pressure during exercise
Correct answer: Oxygen consumption (VO2)
The Fick equation calculates VO2 as cardiac output multiplied by the arteriovenous oxygen difference (a-vO2 diff), linking delivery and extraction of oxygen.
Question 4: Which of the following adaptations is a hallmark of long-term endurance training?
- Increased resting heart rate
- Decreased stroke volume at rest
- Increased mitochondrial density in skeletal muscle (Correct answer)
- Reduced capillary density in muscle tissue
Correct answer: Increased mitochondrial density in skeletal muscle
Endurance training stimulates mitochondrial biogenesis, increasing mitochondrial density and oxidative enzyme activity in trained muscles, improving aerobic capacity.
Question 5: The respiratory exchange ratio (RER) of 1.0 during steady-state exercise indicates that the body is primarily using which fuel?
- Fat
- Protein
- Carbohydrate (Correct answer)
- A 50/50 mix of fat and carbohydrate
Correct answer: Carbohydrate
An RER of 1.0 means the CO2 produced equals the O2 consumed, which is the ratio for complete carbohydrate (glucose) oxidation.
Question 6: What happens to systolic blood pressure during a progressive aerobic exercise test?
- It decreases progressively
- It remains constant throughout
- It increases progressively with increasing workload (Correct answer)
- It increases then drops below resting levels
Correct answer: It increases progressively with increasing workload
Systolic blood pressure rises linearly with increasing exercise intensity due to greater cardiac output, while diastolic pressure typically remains stable or decreases slightly.
Question 7: Which of the following describes the oxygen dissociation curve shift during intense exercise?
- Shift to the left, decreasing oxygen release to tissues
- Shift to the right, increasing oxygen release to tissues (Correct answer)
- No shift; it remains unchanged during exercise
- Shift to the left, increasing hemoglobin's oxygen affinity
Correct answer: Shift to the right, increasing oxygen release to tissues
Increased CO2, decreased pH (acidosis), and elevated temperature during intense exercise cause a rightward Bohr shift, reducing hemoglobin's affinity for O2 and promoting O2 delivery to muscles.
ACE Exercise Physiology 2
Which of the following is the PRIMARY determinant of cardiac output?