ACSM Exercise Physiology 4 — Questions and Answers
Question 1: During resistance exercise, which mechanism accounts for the acute increase in strength observed within the first 4–8 weeks of a training program in untrained individuals?
- Muscle hypertrophy
- Neural adaptations and improved motor unit recruitment (Correct answer)
- Increased myosin heavy chain expression
- Satellite cell proliferation
Correct answer: Neural adaptations and improved motor unit recruitment
Early strength gains (first 4–8 weeks) are primarily due to neural adaptations — improved motor unit recruitment, synchronization, and reduced inhibition.
Question 2: The phosphocreatine (PCr) system can sustain maximal effort for approximately how long before becoming depleted?
- 2–3 seconds
- 8–15 seconds (Correct answer)
- 30–45 seconds
- 2–3 minutes
Correct answer: 8–15 seconds
PCr stores support maximal-intensity exercise for roughly 8–15 seconds before this substrate is largely depleted.
Question 3: At sea level, arterial oxygen saturation (SaO2) in a healthy individual during maximal exercise is typically:
- Below 85%
- 85–90%
- 91–95%
- 95–100% (Correct answer)
Correct answer: 95–100%
In healthy individuals at sea level, SaO2 remains at 95–100% even during maximal exercise because pulmonary gas exchange is usually not limiting.
Question 4: Which cardiovascular variable shows the greatest relative increase from rest to maximal exercise in a trained endurance athlete compared to an untrained individual?
- Maximum heart rate
- Arteriovenous oxygen difference
- Systolic blood pressure
- Stroke volume (Correct answer)
Correct answer: Stroke volume
Endurance training produces cardiac hypertrophy and expanded plasma volume, resulting in a markedly greater trained stroke volume at maximal exercise.
Question 5: Which respiratory adjustment primarily drives the increase in ventilation at the onset of exercise?
- Rising arterial PCO2 detected by central chemoreceptors
- Neural feedforward signals from the motor cortex and proprioceptors (Correct answer)
- Falling arterial PO2 detected by peripheral chemoreceptors
- Increasing blood temperature stimulating the medullary respiratory center
Correct answer: Neural feedforward signals from the motor cortex and proprioceptors
The rapid increase in ventilation at exercise onset is driven by central command (motor cortex) and proprioceptive feedback, not by blood gas changes.
Question 6: An individual's MET (metabolic equivalent of task) during rest is defined as an oxygen uptake of approximately:
- 1.5 mL/kg/min
- 2.5 mL/kg/min
- 3.5 mL/kg/min (Correct answer)
- 5.0 mL/kg/min
Correct answer: 3.5 mL/kg/min
One MET equals approximately 3.5 mL O2/kg/min, representing resting metabolic rate in a seated adult.
Question 7: Which of the following best describes the principle of specificity as it applies to exercise training adaptations?
- Training adaptations are greatest at high intensities regardless of exercise type
- Adaptations are specific to the muscles, energy systems, and movement patterns stressed during training (Correct answer)
- All aerobic training produces identical cardiovascular adaptations
- Strength gains transfer equally across all muscle groups trained
Correct answer: Adaptations are specific to the muscles, energy systems, and movement patterns stressed during training
The specificity principle (SAID) states that physiological adaptations are specific to the type, intensity, and muscles involved in training.
ACSM Exercise Physiology 4
During resistance exercise, which mechanism accounts for the acute increase in strength observed within the first 4–8 weeks of a training program in untrained individuals?