Kinetics and Muscle Structure

Introduction to Kinetics

• Definition: Analysis of the forces that create motion and maintain balance in the human body.
• Focus: Muscles that generate force.

Types of Muscles

1. Cardiac Muscle
   • Found in the heart.
2. Smooth Muscle
   • Found in organs.
3. Skeletal Muscle
   • Focus for this semester.
   • Responsible for voluntary actions.
   • Requires signals from motor neurons to contract and produce movement.
   • Helps in distributing loads by absorbing shock/impact.

Structure of Skeletal Muscle

• Origin: Proximal part of movement.
• Insertion: Distal from insertion.
• Importance: Knowing origin and insertion helps understand muscle function and applications like Kinesio Taping.

Muscle Shapes

• Fusiform Muscles
  • Example: Biceps Brachii, Brachialis.
  • Produce more mobility and range of motion.
• Pennate Muscles
  • Types: Uni-pennate, Bi-pennate, Multi-pennate.
  • Produce more strength but less range of motion.

Cross-Section of a Muscle

• Composed of several Fascicles.
• Each Fascicle contains multiple muscle fibers.
• Smallest functional unit: Sarcomere.
  • Contains proteins Actin and Myosin that bind during muscle contraction to produce strength.
  • Resting position of Sarcomere produces strongest muscle strength.

Muscle Contraction and Strength

• Optimal muscle strength when Sarcomere is at resting position.
• Reduced strength when Sarcomere is too stretched or too shortened.

Active and Passive Components of Muscle Contraction

• Active Components:
  • Intact nervous system for innervation.
  • Proper circulation and nutrition.
  • Muscle's ability to contract and absorb impact.
• Passive Components:
  • Tendon composed of Type I collagen, resistant to stretch.
  • Tendon keeps muscle in shape and provides passive tension.

Muscle Length-Tension Relationship

• Normal Position: Strongest muscle contraction.
• Shortened Position: Reduced binding, reduced strength.
• Stretched Position: Harder binding, reduced strength.
• Total Tension: Sum of active and passive components.
  • Important for training and clinical practice.
  • Stretching can combine passive tension to increase overall strength.

Clinical Implications

• Positioning muscle close to end range can utilize both active and passive components.
• Understanding these concepts is crucial for effective patient training and therapy.