Chapter 7
Torque
A force that produces rotation; common unit of measurement is the Newton meter (Nm).
Motor unit
A motor neuron and all of the muscle fibers that it innervates.
Abduction
A movement in the frontal plane away from the midline of the body.
Eversion
A movement in which the inferior calcaneus (heel bone) moves laterally. The bottom of foot faces outward.
Inversion
A movement in which the inferior calcaneus (heel bone) moves medially. Bottom of foot faces inward.
Eccentric muscle action
A muscle action that occurs when a muscle develops tension while lengthening.
Concentric muscle action
A muscle action that occurs when a muscle is exerting force greater than the resistive force, resulting in a shortening of the muscle.
Hypermobility
A state where a lack of neuromuscular support leads to a joint having more range of motion than it should, greatly increasing the risk of injury at that joint.
Extension
A straightening movement in which the relative angle between two adjacent segments increases.
Scapular protraction
Abduction of scapulae; shoulder blades move away from the midline.
Antagonists
Muscles on the opposite side of a joint that are in direct opposition of agonist muscles.
Synergists
Muscles that assist agonists to produce a movement.
Stabilizers
Muscles that contract isometrically to stabilize the trunk and joints as the body moves.
Joint support systems
Muscular stabilization systems located in joints distal of the spine.
Stretch reflex
Neurological signal from the muscle spindle that causes a muscle to contract to prevent excessive lengthening.
Altered reciprocal inhibition
Occurs when an overactive agonist muscle decreases the neural drive to its functional antagonist.
Posterior
On or toward the back of the body
Contralateral
On the opposite side of the body
Radioulnar supination
Outward rotation of the forearm from a palm-down position to a palm-up position.
Mechanoreceptors
Specialized structures that respond to mechanical forces (touch and pressure) within tissues and then transmit signals through sensory nerves.
Series elastic component
Springlike noncontractile component of muscle and tendon that stores elastic energy.
What does the term force refer to?
The ability of one entity to act on another entity, causing acceleration or deceleration
Elasticity
The ability of soft tissues to return to resting length after being stretched.
Neuromuscular efficiency
The ability of the nervous system to recruit the correct muscles to produce force, reduce force, and dynamically stabilize the body's structure in all three planes of motion.
Feed-forward activation
When a muscle is automatically activated in anticipation of a movement.
Isometric muscle action
When a muscle is exerting force equal to the force being placed on it leading to no visible change in the muscle length.
Altered length-tension relationship
When a muscle's resting length is too short or too long, reducing the amount of force it can produce.
Muscle balance
When all muscles surrounding a joint have optimal length-tension relationships, allowing the joint to rest in a neutral position.
Reciprocal inhibition
When an agonist receives a signal to contract, its functional antagonist also receives an inhibitory signal allowing it to lengthen.
Muscle imbalance
When muscles on each side of a joint have altered length-tension relationships.
Hypomobility
When range of motion at a joint is limited.
Flexion
A bending movement in which the relative angle between two adjacent segments decreases.
Kinetic chain
A concept that describes the human body as a chain of interdependent links that work together to perform movement.
Ligament
A fibrous connective tissue that connects bone to bone.
Tendon
A fibrous connective tissue that connects muscle to bone.
Inferior
Below an identified reference point
Scapular retraction
Adduction of scapulae; shoulder blades move toward the midline.
Frontal plane
An imaginary bisector that divides the body into front and back halves. Movement in the frontal plane includes abduction, adduction, and side-to-side motions.
Sagittal plane
An imaginary bisector that divides the body into left and right halves.
Transverse plane
An imaginary bisector that divides the body into top and bottom halves.
Lateral flexion
Bending of the spine from side to side.
Force
An influence applied by one object to another, which results in an acceleration or deceleration of the second object.
Gait
Biomechanical motion of the lower extremities during walking, running, and sprinting.
Motor development
Change in skilled motor behavior over time throughout the life span.
Sensorimotor integration
Cooperation of the nervous and muscular system in gathering and interpreting information and executing movement.
The muscles of the lower leg, hamstrings, and low back region make up which of the following global muscular subsystems?
Deep longitudinal subsystem (DLS)
Scapular depression
Downward (inferior) motion of the scapulae.
Plantar flexion
Extension occurring at the ankle. Pointing the foot downwards.
Hyperextension
Extension of a joint beyond the normal limit or range of motion.
TRUE OR FALSE? The primary characteristic of closed-chain movements is that the distal segments, such as the person's hands or feet, are not fixed and are able to move freely.
False
Dorsiflexion
Flexion occurring at the ankle.
Isotonic
Force is produced, muscle tension is developed, and movement occurs through a given range of motion. Isotonic muscle actions are subdivided into concentric and eccentric muscle actions.
Muscle synergies
Groups of muscles that are recruited simultaneously by the central nervous system to provide movement.
Motor control
How the central nervous system integrates internal and external sensory information with previous experiences to produce a motor response.
External feedback
Information provided by some external source, such as a fitness professional, video, mirror, or heart rate monitor, to supplement the internal environment.
Motor learning
Integration of motor control processes through practice and experience, leading to a relatively permanent change in the capacity to produce skilled motor behavior.
Radioulnar pronation
Inward rotation of the forearm from a palm-up position to a palm-down position.
What are the three overarching types of muscle actions?
Isotonic, isometric, and isokinetic
Stretch-shortening cycle
Loading of a muscle eccentrically to prepare it for a rapid concentric contraction.
One of the most important concepts in motor control is that muscles are recruited by the nervous system in groups. What are these groups called?
Muscle synergies
Motor behavior
Motor response to internal and external environmental stimuli.
Adduction
Movement in the frontal plane back toward the midline of the body.
Osteokinematics
Movement of a limb that is visible.
Horizontal adduction
Movement of the arm or thigh in the transverse plane from a lateral position to an anterior position.
Horizontal abduction
Movement of the arm or thigh in the transverse plane from an anterior position to a lateral position.
Rotary motion
Movement of the bones around the joints.
Pronation of the foot
Multiplanar movement of the foot and ankle complex consisting of eversion, dorsiflexion, and ankle abduction; associated with force reduction.
Supination of the foot
Multiplanar movement of the foot and ankle complex consisting of inversion, plantar flexion, and ankle adduction; associated with force production.
Isometric
Muscle tension is created without a change in muscle length and no visible movement of the joint.
Internal feedback
Process whereby sensory information is used by the body to reactively monitor movement and the environment.
Medial
Relatively close to the midline of the body
External rotation
Rotation of a body segment away from the middle of the body.
Internal rotation
Rotation of a body segment toward the middle of the body.
Kinesiology
Study of movement as it relates to anatomy and physiology.
Proprioception
The body's ability to naturally sense its general orientation and relative position of its parts.
Human movement system (HMS)
The collective components and structures that work together to move the body: muscular, skeletal, and nervous systems.
Regional interdependence model
The concept describing the integrated functioning of multiple body systems or regions of the body.
Arthrokinematics
The description of joint surface movement; consists of three major types: roll, slide, and spin.
Muscle action spectrum
The full range of eccentric, isometric, and concentric muscle contractions required to perform a movement.
Resting length
The length of a muscle when it is not actively contracting or being stretched.
Flexibility
The normal extensibility of soft tissues that allows for full range of motion of a joint.
Neutral position
The optimal resting position of a joint that allows it to function efficiently through its entire normal range of motion.
Anatomic position
The position with the body erect, the arms at the sides, and the palms forward. It is the position of reference for anatomic nomenclature.
Agonists
The primary muscles providing force for a movement.
What concept describes how the function of one segment of the body can impact other areas?
The regional interdependence model
Length-tension relationship
The resting length of a muscle and the tension the muscle can produce at this resting length.
What is the imaginary line that bisects the body into right and left sides?
The sagittal plane
Biomechanics
The science concerned with the internal and external forces acting on the human body and the effects produced by these forces.
Isokinetic
The speed of movement is fixed, and resistance varies with the force exerted. It requires sophisticated training equipment often seen in rehabilitation or exercise physiology laboratories.
Sarcomere
The structural unit of a myofibril composed of actin and myosin filaments between two Z-lines.
Core
The structures that make up the lumbo-pelvic-hip complex (LPHC), including the lumbar spine, pelvic girdle, abdomen, and hip joint.
Force-couple relationship
The synergistic action of multiple muscles working together to produce movement around a joint.
Myosin
The thick myofilament that acts along with actin to produce muscular contraction.
Actin
The thin, stringlike, myofilament that acts along with myosin to produce muscular contraction.
Amortization phase
The transition from eccentric loading to concentric unloading during the stretch-shortening cycle.
Integrated performance paradigm
To move with efficiency, forces must be dampened (eccentrically), stabilized (isometrically), and then accelerated (concentrically).
Scapular elevation
Upward (superior) motion of the scapulae.
Feedback
Use of sensory information and sensorimotor integration to help the human movement system in motor learning.