Understanding The Kinectic Chain and Human Function

Question 1

Systems for Musculoskeletal Function: Facts

Answer 1

Muscles and joints must interact cooperatively and synergistically to properly move and stabilize the body during physical activity

Recruitment patterns are harmonized via the central nervous system (CNS) so that energy/force is transferred fluidly across joint segments (as shown with the tennis player)

Any loss of energy along the kinetic chain reduces the potential force applied at the point of contact

Functional recruitment for stability and efficient movement occurs through the coordinated actions of three systems:

Passive system – form closure

Active system – force closure

Control system – neural activation and coordination

Question 2

Form closure

Answer 2

efficiency of joint structures; primarily consists of bones and connective tissues

Question 3

Force closure

Answer 3

support of soft tissues which help maintain joint position; primarily consists of muscles and fascia

Question 4

Kinetic chain

Answer 4

refers to the force across body segments or chain of force transfer involved in properly moving the body

Question 5

Local & Global System FACTS

Answer 5

Local and global systems cooperate for movement efficiency and reduce the risk for injury via several mechanisms:

Local systems function in an anticipatory manner before movements/loading to brace the joint or body segment and maximize stability (very important for protecting the spine)

Local systems fire earlier than the fibers of global systems to anchor a motion segment before the global system pulls on it for bodily movement

Activity of local systems in the trunk should precede that of muscles responsible for limb movement (feed-forward response)

Key concept: delayed local system firing allows forces to go unmanaged and can lead to injury

Local-global cooperation must occur during both predictable and unpredictable loading scenarios or performance will suffer

When loading is relative, movements such as the back squat and bent over row have greater relative contribution from the trunk stabilizers due to trunk positioning, and overall load

Question 6

Local stabilizers

Answer 6

Role: Increase muscle stiffness to control segmental movement

Functions: Control neutral joint position; contraction does not produce change in muscle length or movement

Characteristics: fulfill, proprioceptive functions; activity is independent of the direction of movement. Activation is continuous in nature but reactive to offset forces.

Examples: Transverse Abdominis
Pelvic Floor
Diaphragm 
Multifidus
Internal obliques
Supraspinatus

Question 7

Global stabilizer

Answer 7

Role - generate torque to control
rande of movement

• Functions - control the inner and outer range of movement; tend to contract eccentrically
for low-load deceleration of momentum and rotational control

Characteristics: activity is direction dependent . Activation of noncontinuous.

Examples:
Quodratus Lumborum
Psoas Major
externa ano internar Oongues
Rectus Abdominis
Hip Adductors
Traneris
Levator scopala
Serratus Anterior
Rhomboids

Question 8

Global mobilizers

Answer 8

Role - generate torque to
produce movement

• Functions - produce joint movements especially movements in the sagittal plane, tend to contract concentrically and absorb shock forces from impacts

Characteristics-activity is
direction dependent-activation
is non-continuious

• examples

External Oblique
Rectus Abdominis
Erector Spinae
Psoas Major
Latissimmis Dorsi
Gluteus Maximus
Hip adductors
Hamstrings

Question 9

Static stability

Answer 9

the ability to maintain a position without movement while under load – e.g. planks or quadrupeds

Question 10

Integrated model of function

Answer 10

describes the cooperation and coordination between bodily systems

Question 11

Function

Answer 11

suggests the body can manage environments and conditions efficiently, without undue stress or restriction

Question 12

Dysfunction

Answer 12

suggests reduced performance efficiency and injury risk due to musculoskeletal deficiencies that create poor posture, faulty movement patterns, and/or incorrect

Question 13

Components of the integrated model of function:

Answer 13

Form closure – how well a joint aligns

Force closure – the ability of connective tissue to maintain joint positional alignment

Motor control – the proficiency of the neuromuscular system to anticipate and react to external stimuli

Emotion – one’s current psychological orientation which can impact neural activity

Question 14

Form closure:
Continued

Answer 14

Describes the structural aspects of the body and the specific architecture of joints; defining characteristics of joints stem from their structure, orientation, and shape:

If the segments fit together like a puzzle, significant support is provided (hip)

If the connecting surface area is limited, other tissues enhance stability (shoulder)

Question 15

Force closure:
Continued

Answer 15

Includes ligaments, tendons, muscle, and fascia that provide support and stability

Force closure supports any deficiency in form closure via muscular contractions and connective tissue compressive forces

Lack of stability in a joint reduces force production (weakest link in kinetic chain)

Question 16

Motor control

Answer 16

Refers to neuromuscular activation within motor units to produce movement via appropriate force

The magnitude of force and the timing of motor unit activation/deactivation dictate stability

Familiarity and movement practice (rehearsal) is key to improving motor control

Practice improves performance = layman’s understanding of “muscle memory”

Question 17

Emotion facts

Answer 17

Identifies the relationship between the brain and working muscles during physical actions

Emotion is physically expressed: can lead to postural adjustments, promote biomechanical changes (e.g., unnecessary tension), and impact focus

Affects motivation which affects force production

Has the greatest impact on finite actions (e.g., putting during golf)

The use of targeting, location stimuli, and other focal interactions with trained movements to stimulate the brain can improve focus, and therefore performance