Levers and Personality Notes

Levers in Movement and Sport

Introduction to Levers

• Levers are rigid rods that rotate around a fixed pivot (fulcrum) when force is applied.
• They are simple machines.
• Rotation tendency depends on:
  • Magnitude of applied forces
  • Distance between fulcrum and force's line of action
• In human movement, bones act as levers when muscles contract.

Parts of a Lever

• Rigid rod
• Fulcrum (axis)
• Load force
• Effort force
• Moment arm: Perpendicular distance from force's action line to the fulcrum.
• Load arm: Distance from the load to the fulcrum.
• Effort arm: Distance from the effort to the fulcrum.

Mechanical Advantage (MA) of a Lever

• MA indicates how much the effort force is multiplied to overcome the load.
• Calculated as: $MA = \frac{effort \, arm}{load \, arm}$ and $MA = \frac{magnitude \, of \, effort}{magnitude \, of \, load}$
• MA > 1.0 is considered efficient.

Types of Levers

• Classified by the positions of effort and load relative to the fulcrum:
  • First-class
  • Second-class
  • Third-class

First-Class Levers

• Effort and load are on opposite sides of the fulcrum.
• Effort arm can be smaller, equal to, or greater than the load arm.
• Rare in the human body.
• Example: Neck muscles overcoming the weight of the head.

Second-Class Levers

• Effort and load are on the same side of the fulcrum, with the effort arm longer than the load arm.
• MA > 1, meaning a small effort can overcome a large resistance.
• Rare in the human body.
• Example: Calf muscles providing effort when standing on toes (plantarflexion).

Third-Class Levers

• Effort and load are on the same side of the fulcrum, but the effort arm is shorter than the load arm.
• MA < 1, requiring large effort forces to overcome small load forces.
• Advantage: Magnified range of motion and speed.
• Common in the human body.
• Example: Biceps brachii providing effort at the elbow joint to hold a weight.

Levers and Mechanical Advantage

• First-class levers can have MA > or < 1.0
• Second-class levers always have MA > 1.0
• Third-class levers always have MA < 1.0

Levers Inside the Body

• Bones act as levers, rotated by muscles at joints.
• Most muscles operate within first or third-class lever systems.
• Most first-class lever systems have MA < 1.0 due to short moment arms of muscle tendons.

Levers Outside the Body

• External levers can enhance performance in sports.
• Example: Baseball bat; effort is the force, fulcrum is the shoulder, and load is the baseball.

Factors Affecting Moment of Resistance

• The moment of resistance and the training effect on muscles can be varied by:
  • Altering the moment arm of the weight of the body part that is moved.
  • Increasing the load by adding weights.
  • Altering the line of action of the load.

Linking Question: External Levers and Skill Acquisition

• How can changing external levers (e.g., pole length in pole vault) affect skill acquisition?
  • Time to adapt to a shorter/longer pole.
  • Force and coordination requirements.
  • Timing and spatial awareness.
  • Psychological effects on athletes.

Personality

Introduction to Personality

• Personality refers to individual differences in thinking, feeling, and behaving; interaction between genetics and environment.
• Social learning theory: situational approach to behaviour.
• Personality can change over time.

Defining Personality

• Personality: relatively stable and enduring aspects that distinguish individuals (Gross, 1992).
• The stability allows for prediction of behavior and building relationships.

Trait-Based Approaches

• Use psychometric tools to measure personality.
• State: thinking, feeling, behaving at one point in time.
• Trait: consistent across social situations.
• Traits predispose individuals to certain behaviors, but it's not guaranteed.

The Big Five Personality Traits

1. Openness to Experience: Likes trying new things vs. prefers routine.
2. Conscientiousness: Responsible and organized vs. forgetful.
3. Extraversion: Outgoing and social vs. enjoys solitude (introversion).
4. Agreeableness: Friendly and cooperative vs. unkind.
5. Neuroticism: Worries easily vs. emotionally stable.

Measuring Personality

• LOTS data:
  • L-data: Lifetime history
  • O-data: Observations from others
  • T-data: Experimental procedures and standardized tests
  • S-data: Self-reported information

Big Five and Sports Performance

• Extraversion and conscientiousness linked to exercise adherence.
• Neuroticism negatively related to physical activity.

Paradox of Perfectionism

• Setting high standards and being critical of performance.
• Adaptive perfectionism: Focus on high standards without excessive concern over mistakes.
• Maladaptive perfectionism: Focus on high standards with concern over mistakes and others' opinions.

Interactionist View of Personality

• Lewin: Behavior is a function of the person and their environment: $B = f(P, E)$
• Mischel's social-cognitive approach: Considers competencies, encoding strategies, expectancies, and plans.