🪃Principles of Strength and Conditioning Unit 2 – Anatomy and Physiology Fundamentals

Key Anatomical Structures

• Skeletal muscles generate force and movement through contraction and relaxation
• Bones provide structural support, protection for organs, and attachment points for muscles
• Ligaments connect bones to other bones, providing stability and limiting excessive joint movement
• Tendons attach muscles to bones, transmitting the force generated by muscle contraction
• Cartilage covers the ends of bones in joints, reducing friction and absorbing shock
• Fascia is a connective tissue that surrounds and separates muscles, organs, and other structures
• Nerves carry electrical signals between the brain, spinal cord, and muscles to control movement
  • Sensory nerves convey information from receptors to the central nervous system
  • Motor nerves transmit signals from the central nervous system to muscles, initiating contraction

Physiological Systems Overview

• Cardiovascular system consists of the heart, blood vessels, and blood, delivering oxygen and nutrients to tissues
  • Heart pumps blood through the circulatory system
  • Arteries carry oxygenated blood away from the heart to the body's tissues
  • Veins return deoxygenated blood from the tissues back to the heart
• Respiratory system includes the lungs, airways, and respiratory muscles, facilitating gas exchange
  • Diaphragm and intercostal muscles enable breathing by changing the volume of the thoracic cavity
• Endocrine system comprises glands that secrete hormones to regulate various physiological processes
  • Hormones influence growth, development, metabolism, and homeostasis
• Digestive system breaks down food into nutrients, absorbs them, and eliminates waste
• Urinary system filters blood, removes waste products, and regulates fluid and electrolyte balance
• Immune system defends the body against pathogens and foreign substances
• Integumentary system (skin, hair, and nails) provides a protective barrier, regulates body temperature, and synthesizes vitamin D

Muscle Mechanics and Function

• Muscles are composed of bundles of muscle fibers (cells) that contract to generate force
• Muscle fibers contain myofibrils, which are composed of sarcomeres, the basic functional units of muscle contraction
  • Sarcomeres contain thick (myosin) and thin (actin) filaments that slide past each other during contraction
• Muscle contraction is initiated by an action potential from a motor neuron, causing the release of calcium ions
  • Calcium ions bind to troponin, exposing binding sites on actin for myosin heads
  • Myosin heads attach to actin, forming cross-bridges and pulling the thin filaments toward the center of the sarcomere (sliding filament mechanism)
• Types of muscle contractions include concentric (muscle shortens), eccentric (muscle lengthens under tension), and isometric (muscle length remains constant)
• Muscle fiber types are classified as Type I (slow-twitch) and Type II (fast-twitch)
  • Type I fibers have high endurance, low force output, and rely primarily on aerobic metabolism
  • Type II fibers generate high force, fatigue quickly, and rely more on anaerobic metabolism
• Muscles work in pairs called agonists (prime movers) and antagonists to produce smooth, coordinated movements

Skeletal System and Joint Movements

• Skeletal system provides a framework for the body, protects organs, and enables movement
• Bones are composed of compact (dense) and spongy (trabecular) bone tissue
  • Bone matrix consists of collagen fibers and mineral deposits (primarily calcium and phosphate)
• Joints are classified based on their structure and function, including fibrous, cartilaginous, and synovial joints
  • Synovial joints are the most common and allow the greatest range of motion (e.g., hinge, ball-and-socket, gliding)
• Joint movements are described using anatomical planes and axes
  • Sagittal plane divides the body into left and right halves (flexion/extension)
  • Frontal plane divides the body into front and back halves (abduction/adduction)
  • Transverse plane divides the body into upper and lower halves (rotation)
• Range of motion is influenced by joint structure, muscle flexibility, and connective tissue elasticity
• Proper joint alignment and stability are essential for efficient movement and injury prevention

Energy Systems in Exercise

• Energy for muscle contraction is supplied by the breakdown of adenosine triphosphate (ATP)
• Three energy systems produce ATP: phosphagen (ATP-PC), glycolytic, and oxidative
  • Phosphagen system provides immediate energy for high-intensity, short-duration activities (1-10 seconds)
    • Creatine phosphate (PC) is used to rapidly regenerate ATP
  • Glycolytic system predominates in moderate to high-intensity activities lasting 30 seconds to 2 minutes
    • Glucose or glycogen is broken down anaerobically to produce ATP and lactic acid
  • Oxidative system is the primary energy source for low to moderate-intensity activities lasting more than 2 minutes
    • Aerobic metabolism of carbohydrates, fats, and proteins in the presence of oxygen produces ATP
• Energy system contribution depends on the intensity and duration of the activity
  • High-intensity, short-duration activities rely more on the phosphagen and glycolytic systems
  • Low to moderate-intensity, long-duration activities rely primarily on the oxidative system
• Training can improve the efficiency and capacity of each energy system
  • High-intensity interval training enhances the phosphagen and glycolytic systems
  • Endurance training increases the oxidative system's capacity and efficiency

Nervous System and Motor Control

• Nervous system consists of the central nervous system (CNS) and peripheral nervous system (PNS)
  • CNS includes the brain and spinal cord, processing information and generating motor commands
  • PNS includes sensory and motor nerves that carry signals between the CNS and the rest of the body
• Motor units are the functional units of the neuromuscular system, consisting of a motor neuron and the muscle fibers it innervates
  • Recruitment of motor units depends on the force required and the principle of size (Henneman's size principle)
• Proprioception is the sense of body position and movement, provided by sensory receptors in muscles, tendons, and joints
  • Muscle spindles detect changes in muscle length and rate of change
  • Golgi tendon organs monitor muscle tension
• Reflexes are automatic, involuntary responses to specific stimuli
  • Stretch reflex (myotatic reflex) maintains muscle length and posture
  • Golgi tendon reflex (inverse myotatic reflex) protects muscles from excessive tension
• Motor learning involves the acquisition, refinement, and retention of motor skills
  • Stages of motor learning: cognitive, associative, and autonomous
  • Feedback, practice, and task complexity influence motor learning and performance

Adaptations to Training

• Specificity principle states that adaptations are specific to the type of training performed
  • Resistance training induces muscle hypertrophy, increased strength, and neural adaptations
  • Endurance training improves cardiovascular function, capillary density, and oxidative enzyme activity
• Progressive overload involves gradually increasing the stress placed on the body to stimulate further adaptations
  • Factors include intensity, volume, frequency, and rest intervals
• Reversibility principle (detraining) occurs when training stimulus is reduced or removed, leading to a partial or complete loss of adaptations
• Cardiovascular adaptations to endurance training:
  • Increased stroke volume, cardiac output, and oxygen delivery to muscles
  • Decreased resting heart rate and blood pressure
  • Improved capillary density and blood flow distribution
• Skeletal muscle adaptations to resistance training:
  • Hypertrophy of muscle fibers (increased cross-sectional area)
  • Increased motor unit recruitment and firing rate
  • Shift in muscle fiber type composition (Type IIx to Type IIa)
• Bone adaptations to weight-bearing exercise:
  • Increased bone mineral density and content
  • Improved bone strength and resistance to fracture

Practical Applications in Strength and Conditioning

• Assess individual needs, goals, and limitations to design safe and effective training programs
  • Consider age, gender, fitness level, health status, and sport-specific requirements
• Incorporate a variety of training methods to target different physiological adaptations
  • Resistance training for muscle strength, power, and hypertrophy
  • Plyometric training for power, speed, and agility
  • Aerobic and anaerobic conditioning for cardiovascular endurance and metabolic efficiency
• Periodize training programs to manage fatigue, optimize adaptations, and peak for competition
  • Divide training into phases (e.g., preparatory, competitive, and transition) with specific goals and emphases
• Implement proper warm-up and cool-down routines to prepare the body for exercise and promote recovery
  • Dynamic stretching, activation exercises, and sport-specific drills in the warm-up
  • Static stretching and low-intensity aerobic exercise in the cool-down
• Monitor and adjust training based on individual responses, progress, and performance
  • Use objective measures (e.g., strength tests, time trials) and subjective feedback to assess adaptations
  • Modify training variables (intensity, volume, frequency) as needed to optimize results and prevent overtraining
• Emphasize proper technique, posture, and alignment to maximize performance and minimize injury risk
  • Provide clear instructions, demonstrations, and feedback during exercise
  • Correct improper form and progressively refine movement patterns
• Educate athletes on the importance of nutrition, hydration, sleep, and recovery for optimal performance and adaptation to training
  • Provide guidelines for pre, during, and post-exercise nutrition and hydration
  • Encourage adequate sleep and rest between training sessions