Chapter 7 - Human Movement Science

Question 1

Define biomechanics.

Answer 1

The study of applying laws of mechanics and physics to determine how forces affect human movement and to better predict performance in athletic events.

Biomechanics is concerned with the internal and external forces acting on the human body and the effects produced by these forces.

Question 2

Define superior.

Answer 2

Positioned above a point of reference.

Question 3

Define inferior.

Answer 3

Positioned below a point of reference.

Question 4

Define proximal.

Answer 4

Positioned nearest the center of the body, or point of reference.

Question 5

Define distal.

Answer 5

Positioned farthest from the center of the body, or point of reference.

Question 6

Define anterior (or ventral).

Answer 6

On the front of the body (usually point of reference is anatomic position).

Question 7

Define posterior (or dorsal).

Answer 7

On the back of the body (usually point of reference is anatomic position).

Question 8

Define medial.

Answer 8

Positioned near the middle of the body (usually point of reference is anatomic position).

Question 9

Define lateral.

Answer 9

Positioned toward the outside of the body (usually point of reference is anatomic position).

Question 10

Define contralateral.

Answer 10

Positioned on the opposite side of the body.

Question 11

Define joint motion.

Answer 11

Movement in a plane occurs on an axis running perpendicular to the plane.

Question 12

What are the three imaginary planes the body is divided into?

Answer 12

1. Sagittal Plane
2. Frontal Plane
3. Transverse Plane

Question 13

Define the anatomic position.

Answer 13

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 posteriod, medial and lateral, and abduction and adduction apply to the body when it is in the anatomic position.

Question 14

Define the sagittal plane.

Answer 14

• An imaginary bisector that divides the body into left and right halves.
• Occurs around Coronal Axis
• Movement: flexion and extension.
• Examples of predominately Sagittal Plane Movements:
  
  • bicep curls, triceps pushdowns, squats, front lunges, calf raises, walking, running, vertical jump, climbing stairs, shooting a basketball.

Question 15

Define flexion.

Answer 15

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

Question 16

Define extension.

Answer 16

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

Question 17

Define hyperextension.

Answer 17

Extension of a joint beyond normal limit or range of motion.

Question 18

Define the frontal plane.

Answer 18

• An imaginary bisector that divides the body into front and back halves.
• Occurs around an anterior-posterior axis
• Movements: abduction and adduction
• Examples of predominately Frontal Plane Movements:
  
  • side lateral raises, side lunges, side shuffling

Question 19

Define abduction.

Answer 19

• A movement in the frontal plane away from the midline of the body (usually point of reference is anatomic position).
• An increase in the angle between two adjoining segments, but the frontal plane
• Example: side bend (lateral flexion of spine) away from midline

Question 20

Define adduction.

Answer 20

• Movement in the frontal plane back toward the midline of the body (usually point of reference is anatomic position).
• A decrease in the angle between two adjoining segments, but in the frontal plane.
• Example: Shoulder adduction (moves hand from above head back down to side next to hip)

Question 21

Define transverse plane.

Answer 21

-An imaginary bisector that divides the body into top and bottom halves.
-Occurs around a longitudinal or vertical axis
-Movements: internal and external rotation (of limbs), right and left rotation (head and trunk), horizontal abduction and adduction of the limbs, radioulnar (forearm) pronation and supination.
Examples of predominately transverse plane movements:
Cable trunk rotations, dumbbell chest fly, throwing a ball, throwing a frisbee, and swinging a bat.

Question 22

Define internal rotation.

Answer 22

Rotation of a joint toward the middle of the body.

Question 23

Define external rotation.

Answer 23

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

Question 24

Define horizontal abduction.

Answer 24

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

Question 25

Define horizontal adduction.

Answer 25

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

Question 26

What are the primary scapular movements?

Answer 26

1. Retraction (adduction)
2. Protraction (abduction)
3. Elevation
4. Depression

Question 27

Define scapular retraction.

Answer 27

Adduction of scapula; shoulder blades move toward the midline (closer together).

Question 28

Define scapular protraction.

Answer 28

Abduction of scapula; shoulder blades move away from the midline (away from each other).

Question 29

Define scapular depression.

Answer 29

Downward (inferior) motion of the scapula (shoulder blades move downwards).

Question 30

Define scapular elevation.

Answer 30

Upward (and superior) motion of the scapula (shoulder blades move upwards towards the ears).

Question 31

What are the three primary muscle actions?

Answer 31

1. Isotonic (eccentric and concentric)
2. Isometric
3. Isokinetic

Question 32

Define isotonic muscle action.

Answer 32

• Constant muscle tension
• Force is produced, muscle tension develops, and movement occurs through a given range of motion.
• Two types: Eccentric and Concentric

Question 33

Define eccentric muscle action.

Answer 33

• An eccentric muscle action occurs when a muscle develops tension while lengthening.
• Occurs because the contractile force is less than the resistive force
• “Return to resting length” not actually increasing length as though being stretched.
• Synonymous with deceleration (like bench press, the weight of the bar must be decelerated and then stabilized to be properly accelerated.
• Examples: landing from a jump, lowering weight during resistance exercise, all forms of resistance training (walking on treadmill, bench pressing)
• Known as “a negative” - work is actually being done one the muscle because forces move the muscle, rather than the muscle doing the work (or the muscle moving the forces)

Question 34

Define concentric muscle action.

Answer 34

• When a muscle is exerting force greater than the resistive force, resulting in shortening of the muscle and visible joint movement.
• Synonymous with acceleration
• Examples: jumping upward, and the “lifting” phase during resistance training exercise.

Question 35

Define isometric muscle action.

Answer 35

• When a muscle is exerting force equal to the force being placed on it leading to no visible change in the muscle length.
• Example: when an individual pauses during a resistance training exercise in between the lifting and lowering phases.

Question 36

Define isokinetic muscle action.

Answer 36

• When a muscle shortens at a constant speed over the full range of motion.
• The tension in the muscle is at its maximum throughout the whole range of motion.
• Believed to improve strength, endurance, and neuromuscular efficiency.
• Requires use of expensive, sophisticated equipment that measures the a out of force generated by the muscles and adjusts the resistance (load) so that no matter how much the muscle tension is produced, movement remains constant (that harder you push, the more resistance/heavier you/it feel/s)

Question 37

Define force.

Answer 37

• An influence applied by one object to another, which results in an acceleration or deceleration of the second object.
• Characterized by magnitude (how much) and direction (which way they are moving)

Question 38

Describe the length-tension relationship.

Answer 38

• The resting length of a muscle and the tension of the muscle can produce at this resting length.
• There is an optimal muscle length when actin and myosin filaments have the greatest degree of overlap in sarcomere = potential, for maximal force production of that muscle.
• Lengthening beyond optimal, then stimulating it reduces overlap reducing force production.
• Shortening muscle too much then stimulating it creates maximal overlap and allows no further movement to occur between filaments, reducing force output.
• If muscle lengths are altered (ex. misaligned joints = bad posture), then they will not generate the needed force to allow for efficient movement.

Question 39

Define the force-velocity curve.

Answer 39

• The relationship of muscle’s ability to produce tension at differing shortening velocities.
• As velocity of concentric muscle increases, ability to produce force decreases (results thought to be bc overlapping filament may interfere with its ability to form cross-bridges with myosin)
• As velocity of eccentric muscle action increases, the ability to develop force increases (results thought to be bc elastic component of the connective tissue surrounding and within the muscle).

Question 40

Define the force-couple relationship.

Answer 40

• Synergistic action of muscles (muscle groups moving together) to produce movement around a joint.
• Provide divergent pulls on the bones or bones the connect with
• Due to the different attachment sites of each muscle, muscles create pulls at a different angle leading to different forces on the joint.
• The motion depends on the structure of the joint and the collective pull of each muscle involved.
• Proper force-couple relationships can only occur if the muscles are at the right length-tension relationships and the joints have proper arthrokinematics (joint motion), thus allowing proper sensorimotor integration and ultimately proper and efficient movement.

Question 41

Give examples of common force-couples.

Answer 41

1. Muscles: internal and external obliques
   Movement: trunk rotation
2. Muscles: upper trapezius and the lower portion of the serratus anterior
   Movement: upward rotation of the scapula
3. Muscles: gluteus maximus, quadriceps, and calf rotation
   Movement: produce hip and knee extension during walking, running, stair climbing, etc.
4. Muscles: gastrocnemius, peroneus longus, and tibialis posterior
   Movement: performing plantarflexion at the foot and ankle complex
5. Muscles: deltoid and rotator cuff
   Movement: performing shoulder abduction

Question 42

Describe the basic principle of levers in regard to muscle motion in the Human Movement System (HMS).

Answer 42

• A lever consists of a rigid “bar” that pivots around a stationary fulcrum (pivot point).
• In the HMS:
  
  • Fulcrum is the joint axis
  • Bones are the levers
  • Muscles create motion (effort)
  • Resistance can be the weight of the body part, or the weight of an object (barbells and Dumbbells)

Question 43

Give examples of first, second, and third-class levers in the HMS.

Answer 43

1. Fulcrum in middle like a seesaw (nodding head - top of spinal column is fulcrum).
2. Have resistance in the middle with fulcrum and effort on either side like a load in a wheelbarrow (push-up or calf raise - ball of foot fulcrum, body weight is resistance, effort applied by calf musculature).
3. Have effort placed between resistance and the fulcrum, effort travels a shorter distance and must be greater than resistance, most limbs in human body operate as third class levers (forearm- fulcrum is elbow, the effort is applied by the bicep muscle, the load is in the hand like dumbbell when performing bicep curl).

Question 44

Define rotary motion.

Answer 44

-Movement of levers (bones) that rotate around the axis (joints).

Question 45

Define torque.

Answer 45

• A force that produces rotation (the turning effect of a joint in a rotary motion).
• Common unit of torque is the newton-meter or Nm.
• Determined by distance that the weight is from the center of the joint and the muscle’s attachment and the line of pull (direction tension is being applied through tendon) is from the joint will determine efficiency with which muscles manipulate the movement.
• The closer the weight is to the point of rotation (joint), the less torque it creates.
• The farther the weight is from the point of rotation, the more torque it creates.

Question 46

Define motor behavior.

Answer 46

• Motor 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 movement using sensory information from internal and external environments.
• A collective study of motor control, motor learning, and motor development.

Question 47

Define motor control.

Answer 47

• The study of posture and movements with the involved structures and mechanisms used by the CNS to assimilate and integrate sensory information with previous experiences.
• Concerned with what CNS structures are involved with motor behavior to produce movement.
• How the central nervous system integrates internal and external sensory information with previous experiences to produce a motor response.

Question 48

Define motor learning.

Answer 48

-Integration of motor control processes through practice and experience, leading to a relatively permanent change in the capacity to produce skilled movements.

Question 49

Define motor development.

Answer 49

-The change in motor skill behavior over time throughout one’s lifespan.

Question 50

Define muscle synergies.

Answer 50

• Groups of muscles that are recruited by the central nervous system to provide movement.
• Simplifies movement by allowing muscles and joints to operate as a functional unit.
• Through practice of proper movement patterns (proper exercise technique), these synergies become more fluent and automated (muscle memory?).

Question 51

Define proprioception.

Answer 51

• The cumulative sensory input to the CNS from all mechanoreceptors (muscle spindle, Golgi tendon organ, and joint receptors) that provide information about body position, movement, and sensation as it pertains to muscle and joint force.
• Vital source for the CNS to gather info about environment to produce most efficient movement
• Altered after injury.

Question 52

Define sensorimotor integration.

Answer 52

• The ability of the nervous system to gather and interpret sensory information and select and execute the proper motor response.
• The cooperation of the nervous and muscular system in gathering and interpreting information and executing the movement.
• Implies that the nervous system dictates movement.
• It is very important to use the correct technique

Continuous performance of the chest press while rounding and elevating shoulders, can lead to:

• Altered length-tension relationships of muscles (altered muscle length)
• Altered force-couple relationships of muscles (improper recruitment pattern of muscles)
• Altered arthrokinematics (improper joint motion)
• Ultimately leads to shoulder impingement or other forms of muscle injury.

Question 53

Define feedback.

Answer 53

The use of sensory information and sensorimotor integration to help the HMS in the development of permanent neural representations of motor patterns/motor learning.

Question 54

Define internal feedback.

Answer 54

• “Sensory feedback”
• The process whereby sensory information is used by the body via length-tension relationships (posture), force-couple relationships, and arthrokinematics to reactively monitor movement and the environment.
• Acts as a guide, steering HMS to the proper force, speed, and amplitude of movement patterns.

Question 55

Define external feedback.

Answer 55

-Information provided by some external source, such as a health and fitness professional, videotape, mirror, or heart rate monitor, to help supplement the internal feedback.

Two major forms:

1. Knowledge of Results: used after completion of a movement to help inform a client about the outcome of the performance. Helps increase clients’ awareness and augment other forms of sensory feedback, leading to more effective exercise technique. Improves neuromuscular efficiency.
2. Knowledge of Performance: provides information about the quality of the movement during a exercise. Helps client get involved with his/her own sensory process.

Question 56

Define ipsilateral.

Answer 56

Positioned on the same side of the body.