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Chapter 7: Energy Systems and Physical Activity

Muscle Fiber Types

• Slow Twitch:

  • Generate and relax tension slowly.

  • Ideal for long-duration activities (e.g., swimming, cycling, running).

  • Rich in myoglobin, suitable for endurance.

• Fast Twitch:

  • Tense and relax quickly, generate large amounts of tension with lower endurance.

  • Well suited for explosive movements (e.g., sprinting, weightlifting).

  • Comprised of muscle fibers that have low myoglobin concentrations.

Nutritional Components Needed by the Body

• Water: Essential for hydration and bodily functions.

• Vitamins: Important for processes such as immune function and bone health (specific vitamins include D3, C, B, K).

• Minerals: Vital for various body functions (iron, calcium, magnesium, phosphorus, potassium, sodium, chlorine).

• Carbohydrates: Primary energy source.

• Lipids (Fats): Provide energy, insulation, and storage.

• Proteins: Essential for muscle repair and growth.

Human Energy Systems

What are Nutrients?

• Nutrients: Chemical substances from food necessary for energy, cellular activities, and tissue building/repair.

• All organisms require nutrients for life functions.

Key Energy Nutrients

• Carbohydrates: Main source of energy (sugars and starches).

• Proteins: Support growth and repair.

• Fats: Energy storage and insulation.

Role of Carbohydrates

• Glucose: Usual form of carbohydrate assimilation, stored as glycogen in muscles and liver.

• Glycogen: Energy source that can be quickly mobilized during muscular activity.

Page 2: ATP: The Common Energy Molecule

Conversion of Nutrients to Energy

• Nutrients need to be reconstituted into a usable form of energy (ATP).

• Adenosine Triphosphate (ATP): The universal energy molecule for all living organisms, fuels various cellular processes.

Energy Release from ATP

• Energy is released when a phosphate atom is removed from ATP, resulting in ADP + P + Energy.

Resynthesizing ATP

• ATP utilized quickly; requires resynthesis via:

  • Anaerobic (without oxygen): Rapid ATP regeneration for short, powerful activities.

  • Aerobic (with oxygen): More complex, slower generating ATP through complete glucose breakdown.

Page 3: Energy Systems

Two Energy Systems

Anaerobic:

• Quick ATP resynthesis in muscle fibers without oxygen; suitable for short-term physical activity.

Aerobic:

• Requires oxygen; leads to complete glucose breakdown to produce ATP over longer durations.

Three Metabolic Pathways for ATP Restoration

• ATP-PC (Anaerobic Alactic): Supplies quick energy for 10-15 seconds, used in short bursts of strength activities.

• Glycolysis (Anaerobic Lactic): Involves partial glucose breakdown, generating lactic acid, lasting from 15 seconds to 3 minutes, used in intermediate activities.

• Cellular Respiration (Aerobic): Utilizes oxygen for energy, lasting 120 seconds or more.

Page 4: Cellular Respiration Process

Pathways:

• Glycolysis: Optimized for production of ATP and begins aerobic system.

• Krebs Cycle: Eight chemical reactions yielding ATP and high-energy electrons.

• Electron Transport Chain: Produces large amounts of ATP with carbon dioxide and water as byproducts.

Outcomes:

• Aerobic cellular respiration leads to high ATP production; critical in prolonged activities (e.g., marathons).

Page 5: Muscle Fiber Types and Athletic Performance

Slow Twitch Muscle Fibers

• Dark in color; sustain lower tension over longer durations.

• Predominantly found in endurance athletes.

Fast Twitch Muscle Fibers

• Pale in color; generate quick, high tension but lack endurance.

• Crucial for sprinting and explosive movements.

Types of Muscle Fibers

• Type 1 (Slow Oxidative): Fatigue-resistant, reliant on aerobic processes.

• Type 2A (Fast Oxidative Glycolytic): Intermediate properties, suitable for high-speed energy.

• Type 2B (Fast Glycolytic): Store oxygen for quick, anaerobic contractions.

Page 6: Chapter 11: Biomechanics

Nature of Forces and Newton's Laws

• Biomechanics: Studies the body under the influence of forces; pivotal in optimizing athletic performance.

• Force: A push/pull affecting body movement or change in direction, measured in newtons.

Newton's Three Laws of Motion

1. Law of Inertia: An object remains at rest or in motion unless acted on by an external force.

2. Law of Acceleration: F = ma; force applied to an object results in acceleration proportional to the force.

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

Page 7: Motion Types

Linear and Angular Motion

• Linear Motion: Movement in a straight line, all parts moving in unison.

• Angular Motion: Rotation around an axis, analyzed through levers in the body.

Kinematics

• Describes motion: changes in position, speed, direction.

• Levers: Machines changing force direction/size; three classes based on fulcrum position.

Page 8: Classes of Levers

• Class 1: Fulcrum between effort and load (e.g., see-saw).

• Class 2: Load between effort and fulcrum (e.g., wheelbarrow).

• Class 3: Effort between load and fulcrum (e.g., biceps curl).

Page 9: Principles of Biomechanics

Stability

• Definition: Resistance to change in motion; affected by mass and position of the center of mass.

Maximum Effort and Velocity Production

• Utilize all joint movements for maximum force; larger joints first for velocity production.

Impulse-Momentum Relationship

• Greater impulse leads to increased momentum; exemplified in sports like high jump and volleyball.

Page 10: Principles 1-5

1. Stability Principle: Low center of mass enhances stability.

2. Maximum Effort: Utilize all joints for force maximization.

3. Maximum Velocity: Progressively utilize joints from proximal to distal.

4. Impulse-Momentum: Greater impulse creates greater velocity.

5. Direction of Applied Force: Usually opposite to the movement direction.

Page 11: Principles 6-7

Angular Motion Principles

6. Torque Principle: Produced by eccentric forces applied at a distance from the axis.

7. Conservation of Angular Momentum: Adjusting body position to maintain momentum during free fall, as seen in trampoline and skiing.