Human Movement Science Chapter 5 An introduction into Biomechanics

Introduction to Human Movement Science (HMS): HMS collective components: Nervous System (central and peripheral) Skeletal System (articular) Muscular System Biomechanics: The science concerned with the internal and external forces acting on the human body and the effects produced by these forces.

Anatomic Locations: Super: Positioned above a point of reference Inferior: Positioned below a point of reference Proximal: Positioned nearest the center of the body, or point of reference. Medial: Positioned near the middle of the body. Distal: Positioned farthest from the center of the body, or point of reference. Anterior (ventral): On the front of the body Posterior (dorsal): on the back of the body

Anatomic Locations: continued Anterior (ventral): On the front of the body Posterior (dorsal): on the back of the body Lateral: Positioned toward the outside of the body Contralateral: Positioned on the opposite side of the body Ipsilateral: Positioned on the same side of the body

Anatomic Position: The position with the body erect with the arms at the sides and the palms forward. The anatomic position is of importance in anatomy because it is the position of reference for anatomic nomenclature. Anatomic terms such as anterior and posterior, medial and lateral, and abduction and adduction apply to the body when it is in the anatomic position.

Planes of Motion, Axes, and Joint Motions Sagittal Plane: an imaginary bisector that divides the body into left and right halves. Frontal Plane: an imaginary bisector that divides the body into front and back halves. Transverse Plane: an imaginary bisector that divides the body into top and bottom halves.

Inversion vs. Eversion

Muscle Action Spectrum Eccentric: Moving in the same direction as the resistance. Decelerate or reduces force Concentric: Moving in opposite direction of force. Accelerates or produces force

Muscle Action Spectrum Isotonic: Force is produced, muscle tension is developed and movement occurs through a given range of motion Isometric: No visible movement with or against resistance

Eccentric vs. Concentric and Isotonic vs. Isometric

Isokinetic Muscle Action The speed of movement is fixed, and resistance varies with the force exerted.

Motor Behavior and Motor Control Force-couple relationships: Muscle groups moving together to produce movement around a joint. Muscle Synergies: Groups of muscles that are recruited by the central nervous system to provide movement.

Force Couples and Muscle Synergies

Muscle Synergies: Squat (back, smith-machine)

Muscle Synergies: Deadlift

Functional Anatomy of Muscles: Muscle Force: An influence applied by one object to another, which results in an acceleration or deceleration of the second object. Magnitude (how much) and Direction (which way they are moving) Length-Tension Relationship: The resting length of a muscle and the tension the muscle can produce at this resting length. Myosin + Actin = Force

Force-Velocity Curve The force velocity curve refers to the relationship of muscles ability to produce tension at differing shortening velocities. As the Velocity of the concentric muscle action increases, its ability to produce force decreases. Resulting of overlapping the actin filament that may interfere with its ability to form cross-bridges with myosin. Conversely, with eccentric muscle action, as the velocity of muscle action increases, the ability to develop force increases. Resulting of the use of the elastic component of the connective tissue surrounding and within the muscle.

Muscular Leverage and Arthrokinematics (movement in joint surfaces)

Torque: A force that produces rotation. The farther away the object being used for resistance (dumbbell) is away from the point of rotation, the greater the amount of torque created. Example: When holding a dumbbell straight out to the side at arms length (shoulder ___________) the weight is approximately 24 inches from the center of the shoulder joint. Prime Mover Muscle: ______________ If its attachment is approximately 2 inches from the joint center there is a difference of 22 inches (11 times greater). However, if the weight is moved closer to the joint center, to the elbow, the resistance is only approximately 12 inches from the joint center. Meaning the difference is only 10 inches (5 times greater). Weight was reduced by

Load and Torque Relationships

Human Movement Systems (HMS): Motor Behavior The HMS response to internal and external environmental stimuli. The study of motor behavior examines the manner by which the nervous , skeletal, and muscular systems interact to produce skilled movements using sensory information from internal and external environments.

Human Movement Systems (HMS): Motor Behavior Motor Control: CNS integrates internal and external sensory information with previous experiences to produce a motor response. Motor Learning: Integration of motor control processes through practice and experience, leading to a relatively permanent change in the capacity to produce skilled movements. Practice and experience that lead to relative permanent change in ones capacity to produce skilled movements. Motor Development: The change in motor skill behavior over time throughout the lifespan.

Feedback: Internal feedback: The process whereby sensory information is used by the body to reactively monitor movement and the environment. External feedback: Information provided by an external source; fitness professional, videotape, mirror, and or heart rate monitor. Knowledge of results: Feedback used after the completion of a movement, to help inform the client about the outcome of their performance. (good job, how did that feel, etc) Knowledge of performance: Feedback that provides information about the quality of the movement during exercise. Asking client if he/she felt or saw anything different about those reps…