SCS Exercise Physiology & Biomechanics 2 — Questions and Answers
Question 1: Which energy system is the PRIMARY contributor during a 400-meter sprint?
- ATP-PCr system
- Glycolytic system (Correct answer)
- Oxidative phosphorylation
- Beta-oxidation
Correct answer: Glycolytic system
The glycolytic (lactic acid) system dominates during high-intensity efforts lasting approximately 30–120 seconds, such as a 400m sprint.
Question 2: What does the term 'excess post-exercise oxygen consumption' (EPOC) primarily reflect?
- Oxygen stored in myoglobin before exercise
- Elevated oxygen uptake after exercise to restore homeostasis (Correct answer)
- The anaerobic threshold during exercise
- Mitochondrial density in Type II fibers
Correct answer: Elevated oxygen uptake after exercise to restore homeostasis
EPOC represents the elevated oxygen uptake following exercise used to replenish phosphocreatine, clear lactate, restore body temperature, and re-oxygenate blood.
Question 3: The sliding filament theory describes muscle contraction through the interaction of which two proteins?
- Troponin and tropomyosin
- Actin and myosin (Correct answer)
- Titin and nebulin
- Collagen and elastin
Correct answer: Actin and myosin
Actin (thin filament) and myosin (thick filament) form cross-bridges that produce the force generating muscle shortening.
Question 4: Which type of muscle fiber has the HIGHEST oxidative capacity and fatigue resistance?
- Type IIx
- Type IIa
- Type I (Correct answer)
- Type IIb
Correct answer: Type I
Type I (slow-twitch) fibers contain abundant mitochondria and myoglobin, giving them superior oxidative capacity and resistance to fatigue.
Question 5: During downhill running, which joint action at the knee is MOST responsible for eccentric muscle loading?
- Knee extension
- Knee flexion (Correct answer)
- Hip abduction
- Ankle plantar flexion
Correct answer: Knee flexion
The quadriceps contract eccentrically to control knee flexion during the loading phase of downhill running, absorbing ground reaction forces.
Question 6: What is the mechanical advantage of a lever defined as?
- Force arm length divided by resistance arm length (Correct answer)
- Resistance arm length divided by force arm length
- Load times distance from fulcrum
- Muscle cross-sectional area times pennation angle
Correct answer: Force arm length divided by resistance arm length
Mechanical advantage = force arm / resistance arm; a ratio >1 indicates the lever amplifies force, while <1 amplifies speed/range of motion.
Question 7: Which variable BEST determines an athlete's maximal aerobic power output?
- Lactate threshold
- VO2 max (Correct answer)
- Respiratory exchange ratio
- Tidal volume
Correct answer: VO2 max
VO2 max (maximal oxygen uptake) is the gold-standard measure of an athlete's aerobic capacity and maximum rate of oxygen utilization.
SCS Exercise Physiology & Biomechanics 2
Which energy system is the PRIMARY contributor during a 400-meter sprint?