Muscle Function - Prof. Mumo (2026/2027)
Exercise Science Fundamentals | Key Domains: Neuromuscular Physiology (Sliding Filament Theory,
Motor Units), Energy Systems (ATP-PC, Glycolytic, Oxidative), Principles of Training (Specificity,
Overload, Progression), Acute & Chronic Adaptations to Exercise, and Factors Influencing
Performance | Expert-Aligned Structure | Comprehensive Q&A Format
Introduction
This structured Exercise Physiology Q&A set for 2026/2027 provides a comprehensive review of
core training principles and muscle function with correct answers and rationales. It emphasizes the
scientific basis of exercise, linking cellular mechanisms to whole-body performance and adaptation,
essential for students of kinesiology, athletic training, and exercise science.
Q&A Structure:
• Comprehensive Question Bank: (85 QUESTIONS)
Answer Format
All correct answers and physiological explanations must appear in bold and cyan blue,
accompanied by concise rationales explaining the physiological mechanism (e.g., the role of calcium
and ATP in cross-bridge cycling), the dominant energy system for a given activity (e.g., phosphagen
system for a 100m sprint), the principle of training being applied, the expected adaptation from a
specific training stimulus, and why alternative options are physiologically inaccurate or misapply
exercise science principles.
1. During muscle contraction, what triggers the exposure of myosin-binding sites on actin?
A. ATP hydrolysis
B. Calcium binding to troponin
C. Acetylcholine release
D. Sodium influx into the sarcolemma
,B. Calcium binding to troponin
Calcium ions released from the sarcoplasmic reticulum bind to troponin, causing a conformational
shift that moves tropomyosin away from myosin-binding sites on actin, enabling cross-bridge
formation. ATP hydrolysis (A) powers the myosin power stroke but does not expose binding sites.
Acetylcholine (C) initiates depolarization but not directly filament interaction. Sodium influx (D)
propagates the action potential but is upstream of calcium release.
2. Which energy system predominates during a 10-second maximal effort, such as a 100m sprint?
A. Oxidative phosphorylation
B. Anaerobic glycolysis
C. ATP-PC (phosphagen) system
D. Beta-oxidation
C. ATP-PC (phosphagen) system
The ATP-PC system provides immediate energy for high-intensity efforts lasting up to ~10 seconds
by breaking down phosphocreatine to regenerate ATP. Glycolysis (B) dominates from 10–120
seconds. Oxidative systems (A, D) support prolonged, lower-intensity activity.
3. According to the principle of specificity, training adaptations are:
A. Generalized across all movement patterns
B. Specific to the mode, intensity, and duration of exercise
C. Dependent only on total weekly volume
D. Identical for strength and endurance training
B. Specific to the mode, intensity, and duration of exercise
The SAID principle (Specific Adaptation to Imposed Demands) states that physiological adaptations
are highly specific to the type of stress applied. Strength, endurance, speed, and skill improvements
occur primarily in the trained movement pattern and energy system. Options A, C, and D contradict
this foundational concept.
,4. What is the primary reason for increased stroke volume after endurance training?
A. Increased heart rate
B. Left ventricular hypertrophy and plasma volume expansion
C. Reduced parasympathetic tone
D. Higher systolic blood pressure
B. Left ventricular hypertrophy and plasma volume expansion
Endurance training induces eccentric hypertrophy (larger chamber volume) and increases plasma
volume, enhancing preload and thus stroke volume via the Frank-Starling mechanism. Heart rate
(A) typically decreases at rest. Parasympathetic tone (C) increases, not decreases. Blood pressure
(D) often remains stable or decreases.
5. Which motor units are recruited first during low-intensity muscle contractions?
A. Fast-twitch glycolytic (Type IIx)
B. Fast-twitch oxidative-glycolytic (Type IIa)
C. Slow-twitch oxidative (Type I)
D. All motor units simultaneously
C. Slow-twitch oxidative (Type I)
Henneman’s size principle dictates that smaller, fatigue-resistant Type I motor units are recruited
first for low-force tasks. As demand increases, Type IIa then Type IIx units are activated.
Simultaneous recruitment (D) violates this orderly sequence.
6. The accumulation of hydrogen ions (H⁺) during high-intensity exercise primarily results from:
A. Lactic acid dissociation
B. ATP hydrolysis
, C. Carbon dioxide production
D. Creatine phosphate breakdown
A. Lactic acid dissociation
During anaerobic glycolysis, pyruvate is converted to lactate, and lactic acid dissociates into
lactate⁻ and H⁺, contributing to metabolic acidosis and fatigue. While ATP hydrolysis (B) releases H⁺,
the primary source during intense exercise is glycolytic flux exceeding mitochondrial capacity.
7. Which adaptation is most characteristic of resistance training?
A. Increased mitochondrial density
B. Myofibrillar hypertrophy
C. Enhanced capillary density
D. Elevated VO₂ max
B. Myofibrillar hypertrophy
Resistance training primarily increases contractile protein content (myofibrils), leading to muscle
fiber enlargement and strength gains. Mitochondrial density (A), capillarization (C), and VO₂ max
(D) are hallmark adaptations of endurance training.
8. What is the role of ATP in the cross-bridge cycle?
A. Binds to actin to initiate contraction
B. Powers the myosin power stroke and enables detachment
C. Releases calcium from the sarcoplasmic reticulum
D. Activates acetylcholinesterase
B. Powers the myosin power stroke and enables detachment