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Course Content. Introduction to the Course Biomechanical Concepts Related to Human Movement Anatomical Concepts Related to Human Movement Qualitative Analysis of Human Movement. Anatomical Concepts Related to Human Movement. The Skeletal System The Muscular System The Nervous System.
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Course Content • Introduction to the Course • Biomechanical Concepts Related to Human Movement • Anatomical Concepts Related to Human Movement • Qualitative Analysis of Human Movement
Anatomical Concepts Related to Human Movement • The Skeletal System • The Muscular System • The Nervous System
The Muscular System • Organ Level Structure & Function • System Level Structure & Function • Injury to the Musculoskeletal System
The Muscular System • Organ Level Structure & Function • System Level Structure & Function • Injury to the Skeletal System • Musculoskeletal Function
General Structure • ~ 434 muscles • 40%-45% of body weight • 75 pairs of muscles • Organized into compartments • Utilizes 50% of body’s metabolism • Controlled by somatic nervous system
General Function • Provides force/torque for movement • Maintenance of upright posture • Body transport • Object manipulation • Aids in venous return • Maintains body temperature
Organ Level Structure and Function • Structure of the Muscle Organ • Function of the Muscle Organ
Organ Level Structure and Function • Structure of the Muscle Organ • Function of the Muscle Organ
Muscle Tissue – Active Component
Properties of Skeletal Muscle Tissue • Excitability (Irritability) • Conductivity • Contractility • Extensibility • Elasticity
Connective Tissue – Passive Component
Nerve Tissue – Passive Component
Structure of the Muscle Organ • Muscle organ: 40,000 -1,000,000 fibers • Fascicle: 10-200 fibers • Fiber: 8000 fibrils
Organ Level Structure and Function • Structure of the Muscle Organ • Function of the Muscle Organ
Function of the Muscle Organ Force Production
Factors That Affect Force Output • Physiological factors • Cross-sectional area • Fiber type • Neural factors • Muscle fiber activation • Rate of motor unit activation • Biomechanical factors • Muscle architecture • Force-length relationship • Force-velocity relationship
Physiological Factors: CSA Training?
Physiological Factors: Muscle Fiber Type • Type I • Red, SO, slow-twitch • Type IIa • Red, FOG, fast-twitch, intermediate • Type IIb • White, FG, fast-twitch Training??
Factors That Affect Force Output • Physiological factors • Cross-sectional area • Fiber type • Neural factors • Muscle fiber activation • Rate of motor unit activation • Biomechanical factors • Muscle architecture • Force-length relationship • Force-velocity relationship
Neurological Factors: Muscle Fiber Activation • All-or-None Principle • Same fiber type within MU • 10-2000 fibers per MU • 120-580 MUs / muscle • MU size influences precision & force of movement
Neurological Factors: Muscle Fiber Activation • # of activated MUs, force • Training?
Neurological Factors: Rate of Motor Unit Activation • rate of MU activation, force
Single Twitch Multiple Twitch Tetanus Training??
Factors That Affect Force Output • Physiological factors • Cross-sectional area • Fiber type • Neural factors • Muscle fiber activation • Rate of motor unit activation • Biomechanical factors • Muscle architecture • Force-length relationship • Force-velocity relationship
Nonpennate Muscle Pennate Muscle
Ranges of Muscle Pennation in Humans (Yamaguchi et al., 1990)
Nonpennate Muscle Pennate Muscle
Biomechanical Factors: Muscle Architecture • Pennate • Greater force (force ~ PCSA) • Non-pennate • Greater range of muscle lengths • Larger ROM • Greater operating range • Shorten at higher velocities • Training?
Factors That Affect Force Output • Physiological factors • Cross-sectional area • Fiber type • Neurological factors • Muscle fiber activation • Rate of motor unit activation • Biomechanical factors • Muscle architecture • Force-length relationship • Force-velocity relationship
60% 160% Single Joint Muscles 110-120%
Multi Joint Muscles >160% 60%
Factors That Affect Force Output • Physiological factors • Cross-sectional area • Fiber type • Neurological factors • Muscle fiber activation • Rate of motor unit activation • Biomechanical factors • Muscle architecture • Force-length relationship • Force-velocity relationship
110-180% isometric Biomechanical Factors: Force-Velocity Relationship Eccentric Concentric Velocity
Factors that Affect Force Output • Physiological factors • Cross-sectional area • Fiber type • Neurological factors • Muscle fiber activation • Rate of motor unit activation • Biomechanical factors • Muscle architecture • Length-tension relationship • Force-velocity relationship
Summary • Numerous factors affect the force output of the muscle organ. • Identification of these factors allows us to better understand muscle strength and explore alternative training methods that may be effective in increasing muscle strength.