i

Abstract

Balance is a crucial component of daily activity. It is a simplistic concept but the

mechanisms involved in monitoring, adjusting and percieving balance are highly complex. The

three systems associated with balance work together to maintain the body’s centre of mass over

the base of support. This report will discuss the physiology and responsibilities of the vestibular,

visual and the somatosensory systems and their role in balance. This report will also discuss

closed kinetic chain exercises and their progressions to retrain balance in individuals with lower

extremity injuries. The visual system is responsible for percieving movement, locating objects in

space and differentiating between exafferent and reafferent information. The vestibular system is

responsible for monitoring gravity changes and acceleration associated with head movement.

The somatosensory system monitors many bodily changes, but this report will focus on

proprioception. Proprioception is the ability to monitor and percieve the location of body parts

in space with the feedback of muscle spindles and golgi tendon organs. It is concluded that

closed kinetic chain exercises that progress to challenge the visual and somatosensory systems

are successful in retraining balance. It is recommended that the vestibular system be challenged

with rotational and lateral head movements to incorporate all three balance systems.

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Table of Contents

1.0 Introduction...........................................................................................................................1

1.1. Balance...........................................................................................................................1

1.1.1. Visual and Vestibular Systems.............................................................................2

1.1.2. Somatosensory System.........................................................................................4

1.2. Open vs. Closed Kinetic Chain Exercises......................................................................6

2.0 Methods and Findings...........................................................................................................7

2.1. Physical Therapy for the Vestibular System..................................................................7

2.2. Rehabiliation of the Visual System................................................................................8

2.3. Balance Exercises and the Somatosensory System.....................................................10

3.0 Conclusion..........................................................................................................................11

4.0 Recommendations...............................................................................................................12

5.0 Glossary..............................................................................................................................13

6.0 References...........................................................................................................................15

7.0 Appendix.............................................................................................................................17

8.0 Evaluation...........................................................................................................................19

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List of Tables and Figures

Figure 1.0. Anatomical structures of the vestibular labyrinth.....................................................2

Figure 2.0. Diagram of the ampulla within semicircular canals.................................................2

Figure 3.0. Otolith organs at rest and displaced..........................................................................3

Figure 4.0. GTO response to over contraction of bicep muscle..................................................4

Figure 5.0. Patellar reflex depicting muscle spindle activity......................................................5

Figure 6.0. OKC lat pull down vs. CKC pull up.........................................................................6

Figure 7.0. Ankle strategy (left) vs. Hip strategy (right)............................................................9

Table 1.0. Level progression for 26 participants at the end of a 6-week test period................10

1

1.0 Introduction

[name of clinic here] is a multi-disciplinary clinic that deals with a wide range of personal

and motor vehicle injuries to help promote and increase the rate of recovery. The role of the

kinesiology department is to implement the correct stretches and exercises for each individual

and progress accordingly based on therapists’ guidelines and assessment of injuries. A wide

range of injuries are present throughout the clinic, however, those involving the lower

extremities are often associated with one’s inability to maintain one’s balance. There are many

factors that can affect one’s balance, these include tramautic brain injuries, muscle or nerve

damage, concussions, age or visual acuity.

1.1 Balance

It is now understood that balance is maintained by three sensory systems, the vestibular,

visual and somatosensory system (Mohapatra, Krishnan & Aruin, 2011). The stimulation of

either of these systems evokes a deviation in balance and increases body sway. We are able to

depress or remove the systems while training for balance by closing the eyes to remove vision,

standing on a foam pad, one leg or uneven surface to hinder the somatosensory and vestibular

system. Proprioception* can be altered in many ways. Vibration introduced to the muscle

tendons will activate muscle spindles, producing a feeling of instability causing postural tilt in

the direction of the muscle vibrated, also known as vibration-induced falling (Van Ooteghem,

2010). This phenomena only occurs when the individual is not looking at the vibrated limb.

When vision is introduced, the sensation ceases and negates the vibrating effect (Van Ooteghem,

2010). This reflects how much one relies on the visual system for proprioceptive feedback. The

vestibular system is a highly complex system that monitors head movement through a labyrinth

of organs in the inner ear (Gray, n.d.). It works together with the visual system to differentiate

objects moving in our visual space and the movement of one’s own head. When working

optimally, the three components of balance work collectively to produce a stable body,

minimizing deviations from the central base of support by postural sway and reducing the risk of

injury from falls and instability.

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1.1.1 Vestibular and Visual Systems

One cannot describe the visual system and vestibular system individually without

referencing the other. This section will discuss the vestibulo-ocular pathway and its relationship

with balance. The vestibular system

is located in the inner ear and is

made of 3 semicircular canals

(SCCs) and 2 otolith organs, the

saccule and utricle, making up a

structure called the vestibular

labyrinth, shown in Figure 1.0

(Gray, n.d.). The semicircular

canals are responsible for detecting

angular acceleration and are

oriented 90° to each other (Gray, n.d.). Their orientation allows angular acceleration of the head

to be detected in the roll*, pitch* and yaw* directions, corresponding to the x,y,z axes (Gray,

n.d.). See Appendix A for a diagramatic view of each direction. Otolith organs oriented 90° from

one another detect linear changes in head movement, the utricles measure mostly horizontal

acceleration (ie. deceleration) while the saccules responds primarily to vertical acceleration (ie.

gravity) (Gray, n.d.). All 3 SCCs and both otolith organs innervate the vestibulocochlear nerve

(VIIIth CN) (Gray, n.d.).

At the entrance (ampulla) of each semicircular canal there is a gelatinous liquid called cupula

(Rutka, n.d.). Embedded in the cupula are

stereocilia, tiny hairs that extend out from

the vestibulocochlear nerve that respond to

mechanical shearing* in different directions

causing a chemical depolarization* or

hyperpolarization* of the nerve (Rutka,

n.d.). As the head moves, the cupula lags

behind and bends the hairs, resulting in a

reafferant* signal to the brain indicating that

Figure 1.0. Anatomical structures of the vestibular labyrinth.

Figure 2.0. Diagram of the ampulla within semicircular canals

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the head has moved (Rutka, n.d.). In relation to vision, each SCC innervates two ipsi-lateral* and

two contra-lateral* muscles of each eye, with six extraocular muscles in each eye, corresponding

to each of the three SCCs there is an innervation ratio of 2:1 (Rutka, n.d.). This level of control

allows for a fine response in eye movement, keeping a stable retina image (Rutka, n.d.).

Importantly, this allows us to differentiate between subjective and objective movements. This

phenomena can be demonstrated by placing your finger infront of your face and shaking your

head up and down, and left and right while fixing your gaze upon your finger (Clopton, 2007).

Your finger stays stationary while your head moves, but by shaking your finger while your head

is fixed, the finger appears blurry (Clopton, 2007). This is an example of the SCC portion of the

vestibulo-ocular pathway (Clopton, 2007).

Otolith organs lie between the semicircular canals and the cochlea within the vestibular

labyrinth (Rutka, n.d.). Responsible for gravitational movement, the saccule and utricle are

oriented at 90° from each other, detecting linear changes in the horizontal and vertical directions

(Rutka, n.d.). Otolith organs contain a gelatinous matrix* with cilia* projecting from the afferent

nerve endings, similar to the SCCs (Rutka, n.d.). However, the surface of the gelatinous matrix

contains a membrane with a layer of calcium carbonate crystals ontop, increasing the weight of

the membrane (Rutka, n.d.). Otolith mean’s “ear stones” in Greek (Rutka, n.d.). This blanket of

crystals causes drag on the top of the gelatinous matrix when the head is moved causing a

displacement of the matrix resulting in the hairs within the matrix to bend, similar to the function

of the SCCs (Rutka, n.d.). In turn, the otolith organs also stimulate the vestibulocochlear nerve

(Rutka, n.d.).

Figure 3.0 Otolith organs at rest and displaced

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1.1.2 Somatosensory System

The somatosensory* system is a collection of unnamed senses which includes vibration,

temperature, pain and proprioception (Arezzo, Schaumburg & Spencer, 1982). This report will

focus on proprioception and its involvement in balance and reafferent sensory feedback.

Proprioception is termed as the ability to perceive the location of our own body in space

(Van Ooteghem, 2010). It is part of the somatic division, or voluntary division, of the peripheral

nervous system, which includes the sensory neurons of the skin, joints, tendons and muscles

(Van Ooteghem, 2010). During balance rehabilitation there are two structures that are being

targeted and are responsible for fall prevention and limiting postural sway. These are golgi

tendon organs (GTOs) and muscle spindle fibers (Van Ooteghem, 2010).

Golgi tendon organs are innervated by encapsulated 1B nerve endings located at the muscle-

tendon junction and are arranged in series with the muscle and its tendon (Van Ooteghem, 2010).

Since muscles contract towards the muscles belly, the

most tension occurs at the tendons thus stimulating the

GTOs (Van Ooteghem, 2010). Response to tension

prevents the muscle from over contraction and

overexertion that could cause muscular damage at its

origin and insertion points as well as the muscle itself

(Van Ooteghem, 2010). GTOs are associated with a

negative feedback loop where an over contraction felt at

an agonist muscle, the collagen fibrils of the tendons

press on the 1B afferent neurons which synapses at the

spinal cord shutting off the 1A motor neuron of the same

agonist muscle, preventing damage from over contraction

(Van Ooteghem, 2010). This feedback loop also

prevents the muscle from fatigue and therefore

maintains muscle force (Van Ooteghem, 2010).

Figure 4.0. GTO response to over contraction of the bicep muscle

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Opposite GTOs are muscle spindle fibers. Muscle spindles are intrafusal* fibers,

innervated by gamma motor neurons and are located within the muscle belly (Van Ooteghem,

2010). Intrafusal fibers are not to be confused with extrafusal* fibers which are innervated by

alpha motor neurons, as they are both arranged in parallel to each other within the muscle belly

(Van Ooteghem, 2010). Muscle spindle fibers contain 2 sensory components, primary

(annulospiral) endings and the secondary (flower spray) endings (Van Ooteghem, 2010). Primary

endings output signals to the spinal cord via 1A afferent neurons, secondary endings via Group II

afferent neurons (Van Ooteghem, 2010). These components respond to stretching of the muscle,

which is dependent on sarcomere* length. Muscle spindles are involved in a feedback loop, also

known as the “stretch reflex” (Van Ooteghem, 2010). The stretch reflex is activated when the

muscle spindle fibers have been stretched quickly in a short period of time (Van Ooteghem,

2010). This elicits a response of the intrafusal fibers signalling via 1A and Group II afferent

neurons to the spinal cord where they synapse with alpha motor neurons of the agonist and

antagonist muscles (Van Ooteghem, 2010). The “stretch reflex” elicits a contraction of the

stretched agonist muscle and a relaxation of the antagonist muscle. A prime example is the

patellar reflex. The patellar tendon is struck with a reflex hammer, causing a stretch in the

muscle. This sudden stretch in the muscle causes the spindle fibers to respond. Information is

sent to through the stretch reflex loop and the quadriceps contract causing the leg to rise.

Figure 5.0. Patellar reflex depicting muscle spindle activity

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1.2 Open vs. Closed Kinetic Chain Exercises

Exercises can be broken down into two components, open kinetic chain (OKC) and

closed kinetic chain (CKC) exercises. OKC exercises are defined as an exercise where the distal*

segment of a limb (ie. hands, feet) is moving freely (Hooper, Morrissey, Morrissey & King,

2001). Straight leg raise, leg press, lat pull down and knee extension are examples of OKC

exercises. During CKC exercises, the distal end of the segment is fixed throughout the exercise

(Hooper, Morrissey, Morrissey & King, 2001). Isometric shoulder exercises, squats, pull-ups and

push ups are examples of CKC exercises.

Studies have shown that CKC exercises may be more beneficial

in the early rehabilitation stages because of its involvement in

activating more muscle groups in a more functional way rather

than isolating a single muscle group with OKC exercises

(Hooper, Morrissey, Morrissey & King, 2001). CKC exercises

are also conceived at better enhancing functional performance,

more than OKC excercises (Hooper, Morrissey, Morrissey &

King, 2001). For example, a CKC exercise such as a squat recruits twice as much hamstring

activity, greatest activation of quadriceps at full knee flexion as well as more vasti muscle

activation than an OKC leg press exercise (Escamilla, Fleisig, Zheng, Barrentine, Wilk &

Andrews, 1998). However, proper discretion must be taken into consideration when

implementing primarily CKC or OKC exercises to an individual’s routine. For anterior cruciate

ligament injuries, studies have found that greater strain was placed on the ligament with OKC

exercises than CKC exercises (Escamilla, Fleisig, Zheng, Barrentine, Wilk & Andrews, 1998).

However, many studies have concluded that although CKC exercises promotes greater functional

capabilities, OKC exercises must be incorporated to increase torque* in the lever muscle (ie.

tricep, quadriceps) (Escamilla, Fleisig, Zheng, Barrentine, Wilk & Andrews, 1998). This report

will focus on CKC exercises and their implementation in balance rehabilitation.

[The name of your hometown] Physiotherapy and Rehabilitation Centre caters to a large

demographic and a multitude of injuries. Treatments prescribed by the clinicians incorporate

Figure 6.0. OKC lat pull down vs CKC pull up

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many rehabilitation techniques and modalities to promote the healing of musculoskeletal

structures and systems. The role as a kinesiologist is to prescribe exercises and stretches based on

the clinician’s program requests and make changes if necessary. Many individuals at the clinic

experience issues with balance, whether from muscular or neural issues. This report will discuss

the utilization of CKC exercises and other methods to challenge the three balance systems. This

is a non-empirical report where formal reasoning and research of implemented CKC exercises

and rehabilitation methods for balance will be discussed and supplemented with critical analysis.

2.0 Methods and Findings

Balance rehabilitation must incorporate many areas of expertise and treatment to be able

to fully diagnose the root cause of an individual’s balance disorder. At [nonames] Physiotherapy

and Rehabilitation Centre there are a large majority of individuals with balance disorders

stemming from musculoskeletal issues such as lower extremity fractures*, ligament* and

muscular tendon* tears. Therefore, there is greater application of proprioceptive balance training.

This section will discuss methods of vestibular, visual and proprioceptive rehabilitation for

balance with most emphasis on proprioception through CKC exercises.

2.1 Physical Therapy for the Vestibular System

There are two branches of the vestibular system, central and peripheral. Physical therapy

is one method for treating vestibular system dysfunctions. Other forms of intervention include

pharmacological therapy and surgical intervention. This section will discuss the physical therapy

methods for treating the vestibular system. Imbalance in the peripheral vestibular system, which

consists of the inner ear organs, can cause mild to severe vertigo*, nausea and gait*

abnormalities which can be treated in multiple ways in the clinical setting (Brown, Whitney,

Marchetti, Wristley & Furman, 2006). Central vestibular dysfunctions are more difficult to treat

through physical therapy and must address the neurological issues involving the central nervous

system (Brown, Whitney, Marchetti, Wristley & Furman, 2006). Those with peripheral

vestibular dysfunction can benefit most from physical therapy (Brown, Whitney, Marchetti,

Wristley & Furman, 2006).

In a study by Brown et al, patients performed the Dynamic Gait Index (DGI), Timed Up

& Go(TUG) and Five Times Sit-to-Stand (FTSTS). The DGI is composed of 8 gait tasks;

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walking, walking at varying speeds, walking with head movements in the yaw and pitch

directions, walking over and around objects, pivoting and stair climbing (Brown, Whitney,

Marchetti, Wristley & Furman, 2006). TUG is a timed sitting, walking and standing examination

where the patient is asked to stand up from a chair, walk 3 metres and return back to their chair

and sit down (Brown, Whitney, Marchetti, Wristley & Furman, 2006). The FTSTS test measures

balance and lower extremity strength and it requires individuals to rise from a seated position

and sit back down without the aid of their arms (Brown, Whitney, Marchetti, Wristley &

Furman, 2006). The tests cause angular and linear accelerations of the head, exposing the

individual to movements that may cause discomfort and rehabilitating the issue. Significant

improvements in gait and balance were present at patient discharge after vestibular physical

therapy (Brown, Whitney, Marchetti, Wristley & Furman, 2006).

Benign paroxysmal positional vertigo (BPPV) is a common issue in vestibular

dysfunctions and can be treated more intensively with positional exercises and liberatory

maneuvers proposed by Semont et al and Epley (Brandt, 2000). This physical therapy treatment

involves rapid lateral head and trunk tilts to induce the feeling of vertigo. The patient is to remain

in the tilted position until vertigo subsides or duration of 30 seconds (Brandt, 2000). This process

can be repeated in different planes of the head and trunk to stimulate the different SSCs. The

purpose of these maneuvers is to loosen and break down clots that have accumulated in the

endolymph* of the inner ear (Brandt, 2000). The clot decreases the fluidity of the gelatinous

matrix, which lags behind causing nystagmus* and vertigo (Brandt, 2000). These maneuvers can

be performed in home without assistance from a clinician (Brandt, 2000). See Appendix B for a

schematic of the Semont maneuvers.

2.2 Balance and the Visual System

Vision is a crucial component in balance. Not only does vision allow us to detect hazards

and uneven surfaces, it also communicates with the vestibular system and perceive spatial

relationships with respect to objects in the environment (Lord, 2003). Without visual feedback to

the vestibular system, when standing with eyes closed there is a 20-70% increase in postural

sway (Lord, 2003). Impaired visual acuity also causes increases in postural sway and is

associated most with decreased near-visual acuity (Lord, 2003). Decreased peripheral vision is

also a cause of imbalance (Lord, 2003). People are limited in the ways they are able to increase

9

the acuity of their eye sight, therefore must compensate

with greater demand on the vestibular and

somatosensory systems (Lord, 2003).

Those who are visually impaired put more

emphasis on vestibular and somatosensory information

to adjust and monitor balance (Ray, Horvat, Croce,

Mason & Wolf, 2008). Older adults with adverse

vestibular affects and lessened visual acuity place more

priority on their proprioception (Ray, Horvat, Croce,

Mason & Wolf, 2008). It is reported that both

adolescent children and adults who are blind exhibit fear of falling and have decreased postural

stability (Ray, Horvat, Croce, Mason & Wolf, 2008). In a mixed trial where individuals with full

vision closed their eyes and balanced, and blind individuals closed their eyes, imbalance was

similar (Ray, Horvat, Croce, Mason & Wolf, 2008). However, with eyes open, blind individuals

demonstrated similar amounts of imbalance (Ray, Horvat, Croce, Mason & Wolf, 2008). This

indicates that those with vision absent do not fully adapt to vision loss (Ray, Horvat, Croce,

Mason & Wolf, 2008). The greater increase in postural sway was correlated to an increase in hip

shifting strategy, where the individuals reacted with the hip instead of through the ankles and

knees (Ray, Horvat, Croce, Mason & Wolf, 2008). Increased hip strategy can lead to an

increased chance of falls (Ray, Horvat, Croce, Mason & Wolf, 2008).

Therefore, greater emphasis of vestibular and somatosensory training must be implemented to

adapt for an individual’s visual impairment. A study by King et al proposed that rapid upper limb

movement can be beneficial in fall prevention, absorption and protect against head injury and hip

fractures for the visually impaired (King, McKay, Cheng & Maki, 2010). Training individuals to

use their peripheral vision to grasp for stable fixtures such as a handrail can reduce the chance of

falls (King, McKay, Cheng & Maki, 2010). A study was done to determine if there was a delay

in timing and accuracy of central and peripheral vision. Although it is surely advantageous to

reach and grasp with central vision, peripheral vision provides adequate information for balance

recovery for a fall (King, McKay, Cheng & Maki, 2010).

Figure 7.0. Ankle strategy (left) vs. Hip strategy (right)

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2.3 Balance Exercises and the Somatosensory System

Postural control can be described as the attempt to maintain coordination of body

segments without loss of balance for the facilitation of other actions (Strang, Haworth,

Hieronymus, Walsh & Smart, 2010). Postural sway is the continuous movement the body

undergoes to maintain this control (Strang, Haworth, Hieronymus, Walsh & Smart, 2010). Thus,

it can be interpreted that minimum postural sway is required to achieve significant postural

control. Balance can be improved in all demographics by training with balance-specific

exercises. Balance exercises have been shown to strengthen the lower extremities as well as

reduce recurring injuries (Strang, Haworth, Hieronymus, Walsh & Smart, 2010).

Holistic and progressive balance exercises can be prescribed in the clinical and

rehabilitative setting to improve postural control of individuals with balance issues (Strang,

Haworth, Hieronymus, Walsh & Smart, 2010). It has been noted by researchers that a healthy

postural sway reflects the individual’s flexibility, adaptability and automaticity of postural

control(Strang, Haworth, Hieronymus, Walsh & Smart, 2010). A limited, rigid postural sway

indicates a less-adaptable, attention-demanding control of posture (Strang, Haworth,

Hieronymus, Walsh & Smart, 2010).

In a study by Strang et al,

the following holistic balance

exercises were prescribed, within

each exercises were 4 progressive

stages increasing in difficulty.

Single leg stance, balance path,

double leg BOSU, single leg

squat and reach, Bongo Board, 4-

way tube resist and balance,

forward hop, side hop. The

descriptions and progressions of each exercise are illustrated in Appendix C. Vestibular, vision

and proprioception is tested in each of the exercises within their progressive stages. Trials with

eyes closed tested reliance on vision. Squats, forward and lateral hops and the balance path

would stimulate the vestibular system in both linear and angular directions. Proprioception is

Table 1.0. Level progression for 26 participants at the end of a 6-week test period

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tested in each of the trials by progression of exercises from a hard surface to foam surfaces,

inflatable discs, BOSU balls and Bongo Boards (Strang, Haworth, Hieronymus, Walsh & Smart,

2010). There were improvements in balance for each of the balance trials for each individual.

Table 1.0 illustrates the progression of each of the 26 individuals, and the number of successful

individuals to complete each task at the end of the trial period (Strang, Haworth, Hieronymus,

Walsh & Smart, 2010). Findings lead to the understanding that by training with restricted vision

and diminished proprioceptive feedback, a change in postural sway in the normal stance position

and improved postural control was observed (Strang, Haworth, Hieronymus, Walsh & Smart,

2010).

3.0 Conclusions

In a physical rehabilitation setting balance is a featured component in most injuries,

especially those regarding the lower extremities. Composed of an elaborate system of

interconnected feedback pathways, balance is a complex but crucial component in everyday life.

The vestibular labyrinth within the inner ear is continuously monitoring head movement

and can be manipulated and rehabilitated with simple head and trunk movements. Treating for

vertigo and addressing balance issues, exercises can be administered to the individual and be

self-treated in-home or more intensive physical therapy maneuvers can be performed by a

clinician. The SSCs, Utricles and Saccules are targeted with these maneuvers and by reproducing

the symptoms, vertigo and balance issues can be resolved.

Closely linked to the vestibular system, slight alterations in vision can cause imbalance,

increased postural sway by 20-70%, and issues with fall control and fall prevention. By training

reach-and-grasp for the peripheral vision, one can decrease their chance of falling by increasing

the accuracy of their grasp and speed at which they reached. Reducing the amount of hip strategy

used by those visually impaired and instructing the use of the ankle strategy one can also reduce

the chance of falls.

Progressive proprioceptive balance training is an important area to train because it

incorporates all components of balance as well as training the somatosensory system with

perturbations, uneven and unsteady surfaces. Golgi tendons and muscle spindles are active in all

movements but are specifically triggered during high velocity movements and those involved in

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re-establishing balance such as falls, wobble board training, BOSU stance and forward and

lateral hops.

4.0 Recommendations

With extensive research of the physiology of each system and their corresponding

methods of training, [The Cool People Rehab Clinic] should implement a balance training

protocol that incorporates the vestibular as a major component of training. Removal of vision by

performing exercises with eyes closed and the addition of an unstable surface to challenge the

proprioceptive system is commonplace in a rehabilitative setting. However, vestibular training

can be implemented to further challenge vision and the somatosensory system. By having

individuals stand on one leg with eyes closed on an unstable surface while moving their head in

the yaw and pitch directions, all systems are included in one exercise. There are a lot of clinical

based exercises for balance focused on proprioception, by introducing a wobble board, foam mat

or BOSU ball and progressing to eyes closed but few have considered introducing head

movement to stimulate the vestibular system in addition to the other components. Begin with

vestibular movements similar to those mentioned in Section 2.1 and progress to standing and one

foot balance positions to challenge proprioception, then finally removing vision. This

progression will allow for extensive balance training and incorporate all three areas of balance.

5.0 Glossary

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Cilia – minute hairlike organelles lining the surface of cells

Contra-lateral – pertaining to the opposite side

Depolarization – the influx of sodium ions across a membrane, causing an action potential

stimulating the nerve

Distal – situated away from the point of origin

Endolymph – fluid within the labyrinth of the inner ear

Extrafusal – situated outside of a muscle spindle

Fracture – a break in the continuity of the bone

Gait – a pattern of movements for walking or moving on foot

Hyperpolarization – efflux of potassium ions across a membrane preventing or inhibiting an

action potential

Intrafusal – situated within a muscle spindle

Ipsi-lateral – pertaining to the same side

Ligament – fibrous tissue that connects bones to bones

Matrix – a material or substance that specialized structures are embedded

Nystagmus – fast, uncontrollable movement of the eyes

Pitch – forwards and backwards movement of the head on the y-axis

Proprioception – the body’s awareness of the position of its limbs in space

Reafferent – stimulation as a result of one’s own body movements

Roll – lateral movement of the head side to side on the x-axis

Sarcomere – basic unit of striated muscle fibers

Shear – force acting parallel to the transverse plane

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Somatosensory – sensations pertaining to the skin and deep tissues of the body

Tendon – fibrous tissue that connects muscle to bone

Torque – a moment of force to produce rotation about an axis

Vertigo – a feeling of motion, dizziness or confusion

Yaw – rotational movement of the head side to side on the z-axis

6.0 References

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1. Arezzo, J. C., Schaumburg, H. H., & Spencer, P. S. (1982). Structure and function of the somatosensory system: A neurotoxicological perspective. Environmental Health Perspective, 44, 23-30. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1568957/pdf/envhper00461-0029.pdf

2. Brown, K. E., Whitney, S. L., Marchetti, G. F., Wrisley, D. M., & Furman, J. M. (2006). Physical therapy for central vestibular dysfunction. American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation, 87(87), 76-81. doi: 10.1016/j.apmr.2005.08.003

3. Brandt, T. (2000). Management of vestibular disorders. 491-499.

4. Clopton, J. (2007). Balanced vision: How the visual and vestibular system interact. Unpublished manuscript, Retrieved from http://www.sifocus.com/files/Balanced Vision- How the Visual and Vestibular Systems Int….pdf

5. Escamilla, R., Fleisig, G., Zheng, N., Barrentine, S., Wilk, K., & Andrews, J. (1998). Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises. Medicine and science in sports and exercise, doi: 10.1097/00005768-199804000-00014

6. Gray, L. (n.d.). Chapter 10: Vestibular system: Structure and function. Informally published manuscript, Department of Communication Sciences and Disorders, James Madison University, Houston, Tx, Retrieved from http://neuroscience.uth.tmc.edu/s2/chapter10.html

7. Hooper, D. M., Morrissey, M. C., Drechsler, W., Morrissey, D., & King, J. (2001). Open and closed kinetic chain exercises in the early period after anterior cruciate ligament reconstruction. The american journal of sports medicine, 29(2), 167-174.

8. King , E. C., McKay, S. M., Cheng, K. C., & Maki, B. E. (2010). The use of peripheral vision to guide perturbation-evoked reach-to-grasp balance-recovery reactions. 105-118. doi: 10.1007/s00221-010-2434-9

9. Lord, S. R. (2003). Vision, balance and falls in the elderly. Informally published manuscript, Retrieved from http://www.cmellc.com/geriatrictimes/g031209.html

10. Mohapatra, S., Krishnan, V., & Aruin, A. (2011). Postural control in response to an external perturbation: effect of altered proprioceptive information. doi: 10.1007/s00221-011-2986-3

11. Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001. Other Afferent Feedback that Affects Motor Performance. Retrieved from: http://www.ncbi.nlm.nih.gov/books/NBK10986/

12. Purves D, Augustine GJ, Fitzpatrick D, et al., editors. Neuroscience. 2nd edition. Sunderland (MA): Sinauer Associates; 2001. The Otolith Organs: The Utricle and Sacculus. Retrieved from: http://www.ncbi.nlm.nih.gov/books/NBK10792/

13. Ray, C. T., Horvat, M., Croce, R., Mason, R. C., & Wolf, S. L. (2008). The impact of vision loss on postural stability and balance strategies in individuals with profound vision loss. Gait & Posture, 28, 58-61.

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14. Rutka, J. A. (n.d.). Physiology of the vestibular system. Informally published manuscript, Retrieved from http://www.bcdecker.com/SampleOfChapter/1550092634.pdf

15. Strang, A. J., Haworth, J., Hieronymus, M., Walsh, M., & Smart Jr, L. J. (2010). Structural changes in postural sway lend insight into effects of balance training, vision, and support surface on postural control in a healthy population. 1485-1495. doi: 10.1007/s00421-010-1770-6

16. Van Ooteghem, K. (2010). An Introduction to Psychomotor Behaviour. University of Waterloo.

17. Vestibular exercises. Unpublished raw data, University of Mississippi, Jackson, MS, Retrieved from http://www.umc.edu/uploadedfiles/umcedu/content/education/schools/medicine/clinical_science/otolaryngology__communicative_sciences/handouts/vestibularexercise.pdf

7.0 Appendix

A. Diagrammatic view of Roll, Pitch and Yaw directions

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B. Schematic of the Semont maneuvers

C. Description of holistic exercises and their progressions

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