SCS Exercise Physiology & Biomechanics 4 — Questions and Answers
Question 1: Cardiac output (Q) during maximal aerobic exercise is determined by which formula?
- Q = VO2 / a-vO2 difference
- Q = Heart rate × Stroke volume (Correct answer)
- Q = Blood pressure / Vascular resistance
- Q = Tidal volume × Respiratory rate
Correct answer: Q = Heart rate × Stroke volume
Cardiac output equals heart rate multiplied by stroke volume; elite endurance athletes can achieve Q values of 35–40 L/min during maximal exercise.
Question 2: Which neuromuscular mechanism MOST contributes to early-phase strength gains in untrained individuals?
- Muscle hypertrophy
- Pennation angle increase
- Neural adaptations (improved motor unit recruitment and synchronization) (Correct answer)
- Satellite cell proliferation
Correct answer: Neural adaptations (improved motor unit recruitment and synchronization)
Early strength gains (first 4–8 weeks) are primarily neural: improved motor unit recruitment, rate coding, and inter/intramuscular coordination precede hypertrophy.
Question 3: The stretch-shortening cycle (SSC) stores elastic energy PRIMARILY in which structure?
- Muscle belly glycogen stores
- Tendon and connective tissue (Correct answer)
- Sarcoplasmic reticulum
- T-tubule membranes
Correct answer: Tendon and connective tissue
Tendons and series elastic components store mechanical energy during the eccentric (stretch) phase and release it during the concentric (shortening) phase of the SSC.
Question 4: At a given submaximal workload, trained endurance athletes have a LOWER heart rate than untrained individuals PRIMARILY because of:
- Reduced maximal heart rate
- Increased stroke volume due to cardiac hypertrophy (Correct answer)
- Lower arterial oxygen content
- Decreased hemoglobin concentration
Correct answer: Increased stroke volume due to cardiac hypertrophy
Endurance training causes eccentric cardiac hypertrophy (larger left ventricular volume), increasing stroke volume so the same cardiac output requires fewer beats.
Question 5: Which biomechanical principle explains why a shorter pendulum (leg) completes a swing cycle faster?
- Conservation of momentum
- Inverse relationship between pendulum length and natural frequency (Correct answer)
- Newton's third law of reaction forces
- Bernoulli's principle of fluid dynamics
Correct answer: Inverse relationship between pendulum length and natural frequency
Pendulum frequency is inversely proportional to the square root of length; shorter leg segments swing faster, which is why taller athletes may have lower stride cadences.
Question 6: Beta-oxidation is the metabolic pathway responsible for breaking down which substrate?
- Glycogen
- Protein
- Free fatty acids (Correct answer)
- Phosphocreatine
Correct answer: Free fatty acids
Beta-oxidation cleaves free fatty acids into acetyl-CoA units that enter the Krebs cycle, providing large amounts of ATP during prolonged low-to-moderate intensity exercise.
Question 7: Joint stability during dynamic movement is PRIMARILY provided by the interaction of:
- Passive ligamentous restraint alone
- Active muscle co-contraction and passive structures working together (Correct answer)
- Bony geometry only
- Intra-articular fluid pressure
Correct answer: Active muscle co-contraction and passive structures working together
Dynamic joint stability results from the coordinated interplay of passive restraints (ligaments, joint capsule) and active neuromuscular control (muscle co-contraction).
SCS Exercise Physiology & Biomechanics 4
Cardiac output (Q) during maximal aerobic exercise is determined by which formula?