NASM Chapter 7- Human Movement Science

Human Movement Science

Movement represents the integrated functioning of three main systems within the human body: the nervous system, the skeletal system, and the muscular system.

Kinetic Chain

A concept that describes the human body as a chain of interdependent links that work together to perform movement.

What is an example of the Kinetic Chain?

An individual’s arm, shoulder, and spine are interconnected segments that function together to perform movement.

Regional Interdependence

The concept describing the integrated functioning of multiple body systems or regions of the body.

What happens if a part of the kinetic chain isn’t functioning properly?

The entire link is compromised, resulting in less than optimal performance.

Biomechanics

The science concerned with the internal and external forces acting on the human body and the effects produced by these forces (how physics + movement relate, especially in the context of sport & exercise).

Anatomical Position

The position with the body erect, the arms at the sides, and the palms forward.

Kinesiology

While still concerned with the principles of biomechanics, it investigates movement further because it additionally relates to human anatomy and physiology.

What are the three planes of motion?

Sagittal, Frontal, and Transverse.

Multiplanar

Movement patterns that take the body through motions in more than one plane.

Osteokinematic

Movement of a limb that is visible.

Arthokinematic

The description of joint surface movement; consists of three major types: roll, slide, and spin.

Sagittal Plane

An imaginary bisector that divides the body into left and right halves.

Flexion

A bending movement in which the relative angle between two adjacent segments decreases.

Dorsiflexion

Flexion occurring at the ankle.

Extension

A straightening movement in which the relative angle between two adjacent segments increases.

Plantar flexion

Extension occurring at the ankle. Pointing the foot downwards.

Hyperextension

The extension of a joint beyond the normal limit or ROM and may result in injury.

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.

Abduction

A movement in the frontal plane away from the midline of the body.

Adduction

Movement in the frontal plane back toward the midline of the body.

Lateral Flexion

Bending of the spine from side to side.

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.

Transverse Plane

An imaginary bisector that divides the body into top and bottom halves.

Internal Rotation

Rotation of a body segment toward the middle of the body.

External Rotation

Rotation of a body segment away from the middle of the body.

Horizontal Abduction

Movement of the arm or thigh in the transverse plane from an anterior position to a lateral position.

Horizontal Adduction

Movement of the arm or thigh in the transverse plane from a lateral position to an anterior position.

Radioulnar Pronation

Inward rotation of the forearm from a palm-up position to a palm-down position.

Radioulnar Supination

Outward rotation of the forearm from a palm-down position to a palm-up position.

Isotonic

Force is produced as a muscle develops tension while visibly changing in length.

Eccentric

A muscle action that occurs when a muscle develops tension while lengthening

Deceleration

Synonymous with eccentric; more efficient than concentric exercise because it requires less motor units

Concentric

A muscle action that occurs when a muscle is exerting force grater than the resistive force, resulting in a shortening of the muscle; Synonymous with Acceleration.

Motor Unit

A motor neuron and all of the muscle fibers that it innervates.

Isometric

Occurs when the contractile force is equal to the resistive force, leading to no visible change in the muscle length. 

Core

The structures that make up the lumbo-pelvic-hip complex (LPHC), including the lumbar spine, pelvic girdle, abdomen, and hip joint.

Isokinetic

The muscle shortens at a constant speed over the full ROM; Requires sophisticated equipment that measures the amount of force generated by the muscles and adjusts the resistance (load) so that no matter how much muscular tension is produced, movement speed remains constant.

Muscle Action Spectrum

The full range of eccentric, isometric, and concentric muscle contractions required to perform a movement. 

Agonist

The primary muscles providing force for a movement. Ex: Biceps Brachii in Elbow FX

Antagonists

Muscles on the opposite side of a joint that are in direct opposition of agonist muscles. Ex: Triceps during Elbow FX.

Synergist

Muscles that assist agonists to produce a movement. Ex: Infraspinatus+ Teres Minor in Shoulder Ext Rot

Stabilizers

Muscles that contract isometrically to stabilize the trunk and joints as the body moves. Ex: Core during Hip Ext; Rotator Cuff during OH movement.

Feed-Forward Activation

When a muscle is automatically activated in anticipation of a movement. 

Closed Chain

The primary characteristic of closed-chain movements is that the distal segments, such as a person’s hands or feet, are fixed and remain in contact with a stationary surface.

Open Chain

The primary characteristics of open-chain movements is that the distal segments (hands and feet) are not fixed, and they are free to move in space.

What is the difference between open-chain and closed-chain?

Unlike closed-chain exercises, which activate multiple muscles, open-chain exercises tend to focus on isolating the prime mover muscles. Additionally, closed-chain exercises occur on a stationary substance, while open-chain exercises occur in mid-air.

Force

An influence applied by one object to another, which results in an acceleration or deceleration of the second object.

What are forces characterized by?

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.

Resting Length

The length of a muscle when it is not actively contracting or being stretched.

What two filaments have the greatest degree of overlap?

Actin and Myosin

Actin

The thin, stringlike, myofilament that acts along with myosin to produce muscular contraction.

Myosin

Thick filaments

Sarcomere

The structural unit of a myofibril composed of actin and myosin filaments between two Z-lines.

Muscle Balance

When all muscles surrounding a joint have optimal length-tension relationships, allowing the joint to rest in a neutral position.

Altered Length-Tension Relationship

When a muscle’s resting length is too short or too long, reducing the amount of force it can produce.

What position are muscles in that is the basis for poor posture?

The suboptimal position.

Reciprocal Inhibition

When an agonist receives a signal to contract, its functional antagonist also receives an inhibitory signal allowing it to lengthen.

Altered Reciprocal Inhibition

Occurs when an overactive agonist muscle decreases the neural drive to its functional antagonist.

Muscle Imbalance

When muscles on each side of a joint have altered length-tension relationships.

Neural Position

The optimal resting position of a joint that allows it to function efficiently through its entire normal range of motion.

Integrated Performance Paradigm

To move with efficiency, forces must be dampened (eccentrically), stabilized (isometrically), and then accelerated (concentrically).

Stretch-Shortening Cycle

Loading of a muscle eccentrically to prepare it for a rapid concentric contraction.

Series Elastic Component

Springlike non-contractile component of muscle and tendon that stores elastic energy.

Amortization Phase

The transition from eccentric loading to concentric unloading during the stretch-shortening cycle.

Stretch Reflex

Neurological signal from the muscle spindle that causes a muscle to contract to prevent excessive lengthening.

Force Velocity Curve

The force-velocity curve describes the inverse relationship between force and velocity and refers to a muscle’s ability to produce tension at differing contraction velocities.

Tendon

A fibrous connective tissue that connects muscles to bones.

Force Couple Reaction

The synergistic action of multiple muscles working together to produce movement around a joint.

Local Muscular System

Local muscles generally attach on or near the vertebrae and serve the primary purpose of stabilizing the trunk of the body.

Inner Unit

Rotatores, Miltifidus, Transverse abdominis, Diaphragm, Pelvic floor, and Quadratus lumborum.

Global Muscular System

The global muscular system is comprised of larger muscles that initiate movements and tend to function across one or more joints (divided into subsystems).

Deep Longitudinal Subsystem

Involves the Erector spinae, Biceps femoris, Tibialis anterior, and Peroneus tongus, working in a chain.

Posterior Oblique Subsystem

Involves the Latissimus dorsi, Sacroiliac joint, and the gluteus maximus. 

Oblique

Moved down and to the opposite side.

Anterior Oblique Subsystem

Involves the External obliques and the adductors.

Lateral Subsystem

Involves the Quadratus lumborum, Tensor fasciae latae, Gluteus medius, and adductors.

Levers

Consists of a rigid bar that pivots around a stationary pivot point (fulcrum).

1st Class Lever

First-class levers have the fulcrum in the middle, like a seesaw. 

What is an example of a 1st class Lever

Nodding the head, with the top of the spinal column as the fulcrum.

2nd Class Lever

Second-class levers have a resistance in the middle with the fulcrum and effort on either side, similar to a load in a wheel barrow where the axle and wheel are the fulcrum points.

What are examples of second class levers?

When one engages in a full-body push-up or calf raise.

3rd Class Lever

A third-class lever has the effort placed between the resistance and the fulcrum. The effort always travels a shorter distance and must be greater than the resistance.Most limbs of the human body operate as third-class levers.

Roatary Motion

Movement of the bones around the joints.

Torque

A force that produces rotation; the common unit of measurement in the Newton meter (Nm).