NSCA CSCS Exercise Science Principles 4 — Questions and Answers
Question 1: Phosphocreatine (PCr) stored in muscle provides energy primarily through which reaction?
- PCr + ADP → Cr + ATP (catalyzed by creatine kinase) (Correct answer)
- PCr + ATP → Cr + AMP (catalyzed by myokinase)
- PCr + glucose → Cr + 2 ATP (glycolytic coupling)
- PCr + oxygen → Cr + ATP (oxidative coupling)
Correct answer: PCr + ADP → Cr + ATP (catalyzed by creatine kinase)
Creatine kinase rapidly transfers a phosphate group from phosphocreatine to ADP, regenerating ATP without requiring oxygen.
Question 2: Which adaptation explains the increased strength seen in the first 4–8 weeks of resistance training in previously untrained individuals?
- Significant muscle hypertrophy and protein synthesis
- Neural adaptations including improved motor unit recruitment and synchronization (Correct answer)
- Increased bone density and tendon stiffness
- Elevated testosterone and growth hormone baseline levels
Correct answer: Neural adaptations including improved motor unit recruitment and synchronization
Early strength gains in novice trainees are primarily neurological — improved motor unit recruitment, rate coding, and intermuscular coordination — before substantial hypertrophy occurs.
Question 3: Wolff's Law states that:
- Muscles adapt to the specific demands placed upon them
- Bone remodels according to the mechanical stresses applied to it (Correct answer)
- Tendons increase stiffness proportionally to training volume
- Cartilage regenerates in response to compressive loading
Correct answer: Bone remodels according to the mechanical stresses applied to it
Wolff's Law holds that bone is a dynamic tissue that deposits matrix along lines of mechanical stress and resorbs bone where stress is absent.
Question 4: During maximal exercise, which factor is the primary determinant of VO2max?
- Pulmonary diffusion capacity
- Maximal cardiac output (central limitation) (Correct answer)
- Peripheral oxygen extraction by muscles
- Blood buffering capacity for lactate
Correct answer: Maximal cardiac output (central limitation)
In healthy individuals, VO2max is primarily limited by the cardiovascular system's capacity to deliver oxygen (maximal cardiac output), not by the muscles' ability to consume it.
Question 5: The term 'muscle pennation angle' refers to:
- The angle at which muscle fibers insert relative to the line of pull of the muscle (Correct answer)
- The degree of sarcomere overlap in a resting muscle
- The angle of joint rotation during maximal contraction
- The ratio of fast-twitch to slow-twitch fiber cross-sectional area
Correct answer: The angle at which muscle fibers insert relative to the line of pull of the muscle
Pennation angle is the angle between muscle fiber orientation and the muscle's longitudinal axis (line of pull), which affects force transmission and muscle architecture.
Question 6: Which of the following best describes the term 'motor unit'?
- A single muscle fiber and its associated capillary bed
- An alpha motor neuron and all the muscle fibers it innervates (Correct answer)
- The entire muscle belly and its associated nerve supply
- A group of motor neurons sharing the same spinal cord segment
Correct answer: An alpha motor neuron and all the muscle fibers it innervates
A motor unit consists of one alpha motor neuron and all the skeletal muscle fibers it innervates, which all contract together when the neuron fires.
Question 7: During high-intensity anaerobic exercise, intramuscular pH decreases primarily due to:
- Accumulation of lactic acid as a direct cause of acidosis
- Increased hydrogen ion (H⁺) production from ATP hydrolysis and accelerated glycolysis (Correct answer)
- Carbon dioxide accumulation within muscle fibers
- Depletion of bicarbonate buffering capacity in plasma
Correct answer: Increased hydrogen ion (H⁺) production from ATP hydrolysis and accelerated glycolysis
Intramuscular acidosis during intense exercise results from H⁺ accumulation from ATP hydrolysis and the proton release associated with rapid glycolytic flux, not lactic acid dissociation per se.
NSCA CSCS Exercise Science Principles 4
Phosphocreatine (PCr) stored in muscle provides energy primarily through which reaction?