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.