Chapter: Human Movement Science

Know all definitions throughout the chapter

  • Biomechanics: the study of the action of external and internal forces on the living body, especially on the skeletal system.

Location Terminology

  • Superior: referring to a point higher or above
  • Inferior: referring to a point lower or below
  • Proximal: referring to a point closer to the origin of a limb
  • Distal: referring to a point farther from the origin of a limb
  • Anterior (or ventral): referring to a point nearer to the front of the body
  • Posterior (or dorsal): referring to a point nearer to the back of the body
  • Medial: referring to a point nearer to the mid-line of the body
  • Lateral: referring to a point further from the mid-line of the body
  • Contralateral: referring to a point on the opposite side of the body
  • Ipsilateral: referring to a point on the same side of the body

Planes of Motion, Axes and Joint Motions

  • Anatomic position: the erect position of the body with the face and gaze directed anteriorly, the upper limbs at the side, and the palms of the hands directed anteriorly.
  • Sagittal plane: a longitudinal plane that divides the body of a bilaterally symmetrical animal into right and left sections. 
  • Flexion: the act of bending a limb in the sagittal plane that typically decreases a joint angle. 
  • Extension: the act of extending a limb that typically increases a joint angle.
  • Hyperextension: the extension of a part of the body beyond normal limits.
  • Frontal Plane: a vertical plane at right angles to a sagittal plane, dividing the body intoanterior and posterior portions. Also called frontal plane .
  • Abduction: the act of moving a limb in the frontal plane that typically moves the limb away from the mid-line of the body.
  • Adduction: the act of moving a limb in the frontal plane that typically moves the limb back toward the mid-line of the body.
  • Transverse Plane: a plane across the body at right angles to the coronal and sagittal plane and perpendicular to the longitudinal axis of a body or object; also, a plane dividing the body into an upper and lower section.
  • Internal Rotation: the act of rotating a limb in the transverse plane toward the mid-line of the body; or counter-clockwise when viewed from a superior view.
  • External Rotation:  the act of rotating a limb in the transverse plane away from the mid-line of the body; or clockwise when viewed from a superior view.
  • Horizontal Abduction: transverse plane movement similar to that of a rear deltoid fly.
  • Horizontal Adduction: transverse plane movement similar to that of a chest fly.
  • Scapular Retraction:  the act of sliding the shoulder blades toward the mid-line of the body.
  • Scapular Motion: the act of sliding the shoulder blades away from the mid-line of the body.
  • Scapular Depression: the act of sliding the shoulder blades inferiorly
  • Scapular Elevation: the act of sliding the shoulder blades superiorly

Muscle Actions


  • Eccentric muscle action: when a muscle contraction is accompanied by lengthening muscle tissue.


  • Concentric muscle action: when a muscle contraction is accompanied by shortening muscle tissue.


  • Isometric muscle action: when a muscle contraction is accompanied by no change in the length of the muscle tissue.


  • Isokinetic muscle action: when a muscle maintains a constant speed during contraction.
  • Force: movement that results in the slowing down or speeding up of an object.
  • Length-Tension Relationships: optimal length of a muscle results in optimal force production.
  • Force-Couple: a group of muscles that work together to produce force on a joint.
  • Rotary Motion: rotational movement of the joints.
  • Torque: something that produces or tends to produce torsion or rotation; the moment of a force or system of forces tending to cause rotation.

Motor Behavior

  • Motor behavior: connecting the mind and body for an optimal performance response.
  • Motor control: is the process by which humans and animals use their brain/cognition to activate and coordinate the muscles and limbs.
  • Motor learning: the process of improving motor skills through practice, with long-lasting changes in the capability for responding.
  • Motor development: the growth of muscular coordination in an animal.
  • Muscle Synergies: Muscles controlled by the CNS that act to produce the same movement.
  • Proprioception: awareness of the position of one’s body produced by all sensory receptors.
  • Sensorimotor Integration: the cooperation of the nervous and muscular system in gathering and interpreting information and executing movement.

Motor Learning

  • Feedback: a biological system in which the output or response affects the input, the sensory system collects input from the motor system to promote the learning of motor skills.
  • Internal Feedback: what you feel during or after you have performed or practiced the skill. Your feelings provide you with information about the outcome of your motor response.
  • External Feedback: is information you receive about your performance from various sources, usually verbal, visual or written.

Compare to Figure 5.3 – Three Planes of Motion

Planes of Motion

Compare to Table 5.1 – 5.7 – Planes, Motions, and Axes


  • Divides the body into anterior and posterior portions
  • Anterior-Posterior Axis
  • Abduction and Adduction
PlaneJoint MotionAxis of RotationExercise

Adduction/Abduction&Ankle Eversion/ Inversion


Lateral Flexion


Abduction:Barbell shoulder press Cable hip abductionAdduction:

Pull up, Cable hip adduction


  • Divides the body into top and bottom portions
  • Longitudinal or vertical axis
  • Movements include all rotation, pronation, supination, horizontal abduction and adduction.
PlaneJoint MotionAxis of RotationExercise

Internal Rotation External Rotation&Horizontal Adduction Horizontal Abduction


Pronation Supination


Internal Rotation: Band Internal RotationTrunk Rotation: Wood chopHorizontal Adduction: Cable Chest Fly

Horizontal Abduction: Rear delt fly machine


  • Divides the body into left and right halves
  • Coronal or medial-lateral axis
  • Flexion and extension
PlaneJoint MotionAxis of RotationExercise

Flexion:Hamstring curl Barbell curlExtension:

Quad Extension, Triceps Skull Crusher

Compare to Table 5.3 – Common force couples

MusclesMovement Created
Shortening of the biceps brachii, brachioradialis, and brachialisElbow flexion in a Bicep Curl
Shortening of the Psoas major and minor, rectus femoris and illiacusHip Flexion in a leg lift
Shortening of the Pectoralis Major, Subscapularis and latissimus dorsiShoulder internal rotation

Different muscles pull from different angles but all work to produce the same joint movement. The biceps, brachioradialis and brachialis muscle all insert into different locations, but all work to flex the elbow.

Compare to Figure 5.15 – Levers


There are three types of levers.

A first-class lever is a stick where the fulcrum is between the weight and the energy moving the weight (your hands, for example). Some common first-class levers are see-saws, crowbars, pliers, scissors (which use two first-class levers together), and a hammer pulling a nail.

A second-class lever is a stick where the fulcrum is at one end of the stick, you push on the other end, and the weight is in the middle of the stick. Some common second-class levers are doors, staplers, wheelbarrows, and can openers.

A third-class lever is a stick where the fulcrum is at one end of the stick, you push on the middle, and the weight is at the other end of the stick. With a third-class lever, you have to put in more energy than you would just lifting the weight, but you get the weight to move a longer distance in return. Some common examples are a broom, a hoe, a fishing rod, a baseball bat, and our own human arms.