Course Title: KINS 1120
Instructor: Raelene Lang
Institution: Langara College of Higher Learning
Discuss muscle naming conventions with examples.
Describe muscle contraction through sliding filament theory.
Explain the impact of pennation on muscle contraction.
Define general muscle categories (e.g., agonist, synergist).
Understand the length-tension relationship of muscle.
Compare and contrast muscle fiber types.
Discuss how fiber distribution influences athletic performance.
Explain motor unit activation principles (all-or-none, size, gradation of force).
Compare relative force, velocity, and power during muscle contractions.
Essential for efficient training.
Aids comprehension of human movement.
Helps identify which muscles produce specific movements.
Assists in recognizing faulty movement patterns for safer program development.
Example: Knee pain or lack of range of motion.
SAID Principle: Specific Adaptations to Imposed Demands; specific adaptations require corresponding stressors.
Common muscle names based on shape include:
Deltoideus
Rectus Abdominis
Rhomboideus Major
Trapezius
Latissimus Dorsi
Size nomenclature examples:
Gluteus Maximus
Pectoralis Major
Peroneus Brevis
Gluteus Minimus
Longissimus Thoracics
Vastus Lateralis
Examples:
Biceps Femoris (two attachments)
Triceps Brachii (three attachments)
Quadriceps (four attachments)
Examples:
Flexor Digitorum Superficialis (superficial attachment)
Obliquus Internus Abdominis
Position nomenclature includes:
Tibialis Anterior
Infraspinatus
Vastus Medialis
Examples of function types:
Flexor Carpi Radialis
Pronator Teres
Supinator
Adductor Magnus
Skeletal Muscle Structure
Composed of muscle tissue, connective tissue, nerves, and blood vessels.
Epimysium: Outer fibrous connective tissue layer contiguous with tendons.
Muscle fibers grouped into bundles (fasciculi) surrounded by Perimysium (CT surrounding fasciculi).
Endomysium: CT surrounding individual muscle fibers.
Sarcoplasm: Contains proteins, glycogen, fats, enzymes, and organelles.
Connection between motor neuron and muscle fiber;
Each muscle fiber innervated by a single NMJ.
Motor unit consists of one motor neuron and all muscle fibers it innervates.
Muscle fibers contract together under stimulation from the motor unit.
Motor units can be either fast-twitch or slow-twitch depending on the muscle fiber type stirred.
Resting Phase: Low calcium in myofibril.
Excitation-Contraction Coupling: Calcium release triggers actin binding sites.
Contraction Phase (Power Stroke): Myosin heads contract and release ADP and Pi.
Relaxation Phase: Calcium pumped back, ceasing actin-myosin interactions.
Definition of Flex: Decrease angle at a joint.
Forces produced by muscle contractions enable movement across joints.
**Agonist vs. Antagonist: **
Agonist muscles perform the action while antagonists oppose it.
Additional roles include synergists and stabilizers for joint stability.
Refers to how the tension produced during a muscle twitch is influenced by the sarcomere length before contraction.
Optimal length improves force production; deviations (too short/too long) can reduce effectiveness.
Type I: Slow-twitch (oxidative), fatigue-resistant, darker due to myoglobin.
Type IIa: Fast-twitch (oxidative-glycolytic).
Type IIx: Fast-twitch (glycolytic), contract rapidly but fatigue quickly.
Characteristic | Type I | Type IIa | Type IIx |
---|---|---|---|
Motor Neuron Size | Small | Large | Large |
Recruitment Threshold | Low | Intermediate | High |
Fiber Diameter | Small | Intermediate | Large |
Conduction Velocity | Slow | Fast | Fast |
Fatigue Resistance | High | Intermediate | Low |
Force Production | Low | Intermediate | High |
Color | Red | Red/White | White |
Influences physical capacity and athletic performance. For example:
Soleus: High Type I composition, crucial for endurance.
Triceps Brachii: Higher Type II composition, transmits larger forces.
All-or-None: All fibers in a motor unit activate together.
Size Principle: Small motor units (Type I) activated first.
Gradation of Force: Achieved through frequency of activation and number of recruited units.
The force and velocity of contraction are inversely related.
Power Definition: Power is the product of force and velocity.