_Chapter 3 - Biomechanics

Chapter 3 - Biomechanics

Concept of Human Movement

• Understanding human movement from a mechanical perspective.

Newton's Laws of Motion

Key Concepts

1. Inertia: Objects at rest remain at rest unless acted upon by an external force.

   • Example: A soccer ball continues in motion until kicked.

2. Acceleration: A force applied will produce a change in motion in proportion to the applied force and mass.

3. Action-reaction: For every action, there is an equal and opposite reaction.

   • Example: When two objects collide, they exert forces equal in size and opposite in direction.

Related Terms

• Force: The push or pull on an object.

• Weight: The force exerted by gravity on an object.

• Friction: The resistance that one surface or object encounters when moving over another.

• Axis: The line about which a rotating body moves.

• Angle of release: The angle at which an object is projected into the air.

• Resistance: Any force that opposes the motion of an object.

• Height of release, Speed of release, Projectile, Levers (3 classes).

• Analyzing human movement from a biomechanical perspective includes concepts of linear and angular motion, equilibrium, velocity/speed, stability, momentum, impulse, and balance.

What is Biomechanics?

• The science studying living things from a mechanical perspective.

• Used by elite athletes to enhance performance, equipment, and technique.

• Principles of biomechanics lead to improved performance and efficiency in sports and physical activity.

Types of Biomechanical Analysis

• Quantitative Analysis: Involves numerical data collection.

  • Example: Measuring time in a 200m race, analyzing stride rates and lengths.

• Qualitative Analysis: Involves descriptive techniques.

  • Example: Comments on an athlete's starting technique based on their body position.

Key Biomechanical Concepts

Force, Torque, and Momentum

• Force: Defined as a push or pull; can change an object's shape or motion.

  • Formula: Force = Mass x Acceleration.

• Torque: The turning effect produced by a force; it influences angular motion.

• Momentum: The measure of motion an object possesses.

  • Formula: Momentum = Mass x Velocity.

  • High momentum is associated with higher velocity.

  • Example: A heavier moving player will be less affected in a collision.

Types of Motion in Human Movement

• Linear Motion: Involves straight-line movement.

  • Example: Jogging forward.

• Angular Motion: Rotation around an axis.

• Projectile Motion: Objects in the air influenced by gravity and air resistance.

Factors Influencing Projectile Motion

1. Angle of Release: Affects flight path.

2. Speed of Release: Determines distance and height.

3. Height of Release: Optimizes angle and trajectory based on launch height.

Equilibrium and Stability

• Equilibrium: A state where all forces and torques are balanced, leading to constant velocity.

• Static Equilibrium: Must meet conditions to maintain stationary positions.

• Dynamic Equilibrium: Involves constant velocity movement.

Factors Affecting Stability

1. Base of Support: A larger base increases stability.

2. Centre of Gravity (COG): The mass distribution influences stability.

3. Line of Gravity: Should align with the base of support for improved stability.

4. Body Mass and Friction: Greater mass requires more force to disrupt equilibrium; increased friction enhances stability.

Lever Mechanics in Human Movement

• Description of Levers: Rigid bars (bones), pivot points (joints), resistance, and applied force.

• Classifications of Levers:

  • 1st Class: Axis between force and resistance; seen in balancing actions.

  • 2nd Class: Resistance between force and axis; great for moving heavy loads.

  • 3rd Class: Force between resistance and axis; advantageous for speed and range of motion.

Mechanical Advantage of Levers

• Calculated by the ratio of force arm to resistance arm.

• Benefits of Mechanical Advantage:

  • 1 requires less effort to move resistance.

  • <1 increases range of motion and speed but requires greater force.

Conclusion

• Mastery of biomechanics enhances understanding of movement mechanics and improves athletic performance. Understanding these principles can significantly aid in training and competition, contributing to both physical efficiency and injury prevention.