PhysioSensing SesingFuture Instructions for use

Clinical Practice Manual
BALANCE
Assessment & Training

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Version Manual: April 2018
The information contained in this manual was partially or fully
taken from the work of several authors and sources not being
original of the company Sensing Future Technologies. This
manual is intended to be a compilation of scientific evidence
applicable to the use of PhysioSensing and is currently
accessible to anyone. Anyone who reads this manual is able to
find more sources of information on this field or contact the
original authors.
Visit us:
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Table of contents
1. Balance 3
1.1. Good balance is often taken for granted 3
1.2. What is balance? 3
1.3. Sensory input 3
1.4. Input from the eyes 4
1.5. Input from the muscles and joints 4
1.6. Input from the vestibular system 4
1.7. Integration of sensory input 5
1.8. Processing of conflicting sensory input 5
1.9. Motor output 5
1.10. Motor output to the muscles and joints 6
1.11. Motor output to the eyes 6
1.12. The coordinated balance system 6
2. Assessment protocols 7
2.1. modified Clinical Test of Sensory Interaction on Balance - mCTSIB 7
2.2. Limits of Stability - LOS 9
2.3. Rhythmic Weight Shift - RWS 12
2.4. Weight Bearing/Squat - WBS 14
2.5. Unilateral Stance - US 16
2.6. Fall Risk - FR 17
3. Balance assessment and training applications 20
4. Scientific Evidence 21
5. Bibliography 30

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1. Balance
1.1. Good balance is often taken for granted
Good balance is often taken for granted. Most people don’t find it difficult to walk across a
gravel driveway, transition from walking on a sidewalk to grass, or get out of bed in the
middle of the night without stumbling. However, with impaired balance such activities can be
extremely fatiguing and sometimes dangerous. Symptoms that accompany the unsteadiness
can include dizziness, vertigo, hearing and vision problems, and difficulty with concentration
and memory.
1.2. What is balance?
Balance is the ability to maintain the body’s center of mass over its base of support (Figure
1). A properly functioning balance system allows humans to see clearly while moving,
identify orientation with respect to gravity, determine direction and speed of movement, and
make automatic postural adjustments to maintain posture and stability in various conditions
and activities. Balance is achieved and maintained by a complex set of sensorimotor control
systems that include sensory input from vision (sight), proprioception (touch), and the
vestibular system (motion, equilibrium, spatial orientation); integration of that sensory input;
and motor output to the eye and body muscles. Injury, disease, certain drugs, or the aging
process can affect one or more of these components. In addition to the contribution of
sensory information, there may also be psychological factors that impair our sense of
balance.
Figure 1 –Example of the center of mass in balance and outside the base of support (unstable -
person will fall).
1.3. Sensory input
Maintaining balance depends on information received by the brain from three peripheral
sources: eyes, muscles and joints, and vestibular organs (Figure 2). All three of these
information sources send signals to the brain in the form of nerve impulses from special
nerve endings called sensory receptors.
Balance Outside base of support

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Figure 2 –The human balance system: balance is achieved and maintained by a complex set of
sensorimotor control systems.
1.4. Input from the eyes
Sensory receptors in the retina are called rods and cones. Rods are believed to be tuned
better for vision in low light situations (e.g. at night time). Cones help with color vision, and
the finer details of our world. When light strikes the rods and cones, they send impulses to
the brain that provide visual cues identifying how a person is oriented relative to other
objects. For example, as a pedestrian takes a walk along a city street, the surrounding
buildings appear vertically aligned, and each storefront passed first moves into and then
beyond the range of peripheral vision.
1.5. Input from the muscles and joints
Proprioceptive information from the skin, muscles, and joints involves sensory receptors that
are sensitive to stretch or pressure in the surrounding tissues. For example, increased
pressure is felt in the front part of the soles of the feet when a standing person leans
forward. With any movement of the legs, arms, and other body parts, sensory receptors
respond by sending impulses to the brain. Along with other information, these stretch and
pressure cues help our brain determine where our body is in space. The sensory impulses
originating in the neck and ankles are especially important. Proprioceptive cues from the
neck indicate the direction in which the head is turned. Cues from the ankles indicate the
body’s movement or sway relative to both the standing surface (floor or ground) and the
quality of that surface (for example, hard, soft, slippery, or uneven).
1.6. Input from the vestibular system
Sensory information about motion, equilibrium, and spatial orientation is provided by the
vestibular apparatus, which in each ear includes the utricle, saccule, and three semicircular
canals. The utricle and saccule detect gravity (information in a vertical orientation) and linear
movement. The semicircular canals, which detect rotational movement, are located at right
angles to each other and are filled with a fluid called endolymph. When the head rotates in
the direction sensed by a particular canal, the endolymphatic fluid within it lags behind
because of inertia, and exerts pressure against the canal’s sensory receptor. The receptor

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then sends impulses to the brain about movement from the specific canal that is stimulated.
When the vestibular organs on both sides of the head are functioning properly, they send
symmetrical impulses to the brain.
1.7. Integration of sensory input
Balance information provided by the peripheral sensory organs –eyes, muscles and joints,
and the two sides of the vestibular system –is sent to the brain stem. There, it is sorted out
and integrated with learned information contributed by the cerebellum (the coordination
center of the brain) and the cerebral cortex (the thinking and memory center). The
cerebellum provides information about automatic movements that have been learned
through repeated exposure to certain motions. For example, by repeatedly practicing serving
a ball, a tennis player learns to optimize balance control during that movement. Contributions
from the cerebral cortex include previously learned information; for example, because icy
sidewalks are slippery, one is required to use a different pattern of movement in order to
safely navigate them, see Figure 3.
Figure 3 –Balance control system.
1.8. Processing of conflicting sensory input
A person can become disoriented if the sensory input received from his or her eyes, muscles
and joints, or vestibular organs sources conflicts with one another. For example, this may
occur when a person is standing next to a bus that is pulling away from the curb. The visual
image of the large rolling bus may create an illusion for the pedestrian that he or she –rather
than the bus is moving. However, at the same time the proprioceptive information from his
muscles and joints indicates that he is not actually moving. Sensory information provided by
the vestibular organs may help override this sensory conflict. In addition, higher level
thinking and memory might compel the person to glance away from the moving bus to look
down in order to seek visual confirmation that his body is not moving relative to the
pavement.
1.9. Motor output
As sensory integration takes place, the brain stem transmits impulses to the muscles that
control movements of the eyes, head and neck, trunk, and legs, thus allowing a person to
both maintain balance and have clear vision while moving.

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1.10. Motor output to the muscles and joints
A baby learns to balance through practice and repetition as impulses sent from the sensory
receptors to the brain stem and then out to the muscles form a new pathway. With repetition,
it becomes easier for these impulses to travel along that nerve pathway –a process called
facilitation –and the baby is able to maintain balance during any activity. Strong evidence
exists suggesting that such synaptic reorganization occurs throughout a person’s lifetime of
adjusting to changing motion environs.
This pathway facilitation is the reason dancers and athletes practice so arduously. Even very
complex movements become nearly automatic over a period of time. This also means that if
a problem with one sensory information input were to develop, the process of facilitation can
help the balance system reset and adapt to achieve a sense of balance again.
For example, when a person is turning cartwheels in a park, impulses transmitted from the
brain stem inform the cerebral cortex that this particular activity is appropriately
accompanied by the sight of the park whirling in circles. With more practice, the brain learns
to interpret a whirling visual field as normal during this type of body rotation. Alternatively,
dancers learn that in order to maintain balance while performing a series of pirouettes, they
must keep their eyes fixed on one spot in the distance as long as possible while rotating their
body.
1.11. Motor output to the eyes
The vestibular system sends motor control signals via the nervous system to the muscles of
the eyes with an automatic function called the vestibulo-ocular reflex (VOR). When the head
is not moving, the number of impulses from the vestibular organs on the right side is equal to
the number of impulses coming from the left side. When the head turns toward the right, the
number of impulses from the right ear increases and the number from the left ear decreases.
The difference in impulses sent from each side controls eye movements and stabilizes the
gaze during active head movements (e.g., while running or watching a hockey game) and
passive head movements (e.g., while sitting in a car that is accelerating or decelerating).
1.12. The coordinated balance system
The human balance system involves a complex set of sensorimotor-control systems. Its
interlacing feedback mechanisms can be disrupted by damage to one or more components
through injury, disease, or the aging process. Impaired balance can be accompanied by
other symptoms such as dizziness, vertigo, vision problems, nausea, fatigue, and
concentration difficulties.
The complexity of the human balance system creates challenges in diagnosing and treating
the underlying cause of imbalance. The crucial integration of information obtained through
the vestibular, visual, and proprioceptive systems means that disorders affecting an
individual system can markedly disrupt a person’s normal sense of balance. Vestibular
dysfunction as a cause of imbalance offers a particularly intricate challenge because of the
vestibular system’s interaction with cognitive functioning, and the degree of influence it has
on the control of eye movements and posture.

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2. Assessment protocols
2.1. modified Clinical Test of Sensory Interaction on Balance -
mCTSIB
Use the mCTSIB to quantify postural sway velocity (Figure 4) during four sensory conditions:
1. Eyes open firm surface;
2. Eyes closed firm surface;
3. Eyes open unstable surface (foam);
4. Eyes closed unstable surface (foam).
Each condition has three trials of 10 seconds.
The mCTSIB is designed to help the clinician assess the need for further testing in patients
with complaints related to balance dysfunction, and to establish objective baselines for
treatment planning and outcome measurement. The mCTSIB cannot provide impairment
information specific to individual sensory, balance, or motor systems.
Figure 4 –Simplified illustrations of the center of pressure, sway angle and sway velocity (°/s).
At the end of performing all the conditions of the protocol it is possible to save the following
balance data and generate a clinical report (Figure 5).
Data
Description
Trial time
Elapsed time: 10 seconds. In the case of loss of balance, appears the
time until the fall has occurred
Sway velocity
Distance travelled by the center of pressure divided by the test time
(°/s). If a fall occurs the value is 6 °/s
Mean sway velocity
Mean sway velocity for each condition
Composite sway velocity
Mean sway velocity for all 12 trials
COP alignment
Patient’s initial COP position relative to the base of support center at the
beginning of each test, expressed as a percentage of the Limit of
Stability (LOS) and degrees
COP

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Figure 5 –Example of the results section of the mCTSIB clinical report.
Normal Response (indicated by green): The four conditions of the mCTSIB are designed to
simulate conditions frequently encountered in daily life activities. Normal individuals maintain
their COG near the center of the support base and minimize their sway regardless of the
sensory challenge or condition.
Abnormal Response (indicated by red): For most patients with disequilibrium (with or without
established etiology), the mCTSIB will document the presence of a balance problem and
provide the information required to support further assessments. It also provides focus for
the rehabilitation plan.
Clinical Significance: The mCTSIB can also be used, to a limited extent, to document
progress in a rehabilitation program. Although the results of the mCTSIB can be used to
distinguish normal balance performance versus abnormal balance performance, it cannot be
used to discern the specific patterns of dysfunction. The combination of the mCTSIB and

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LOS forms an objective screening tool for balance problems that can differentiate those
patients who will benefit from a course of rehabilitation from those who require further
diagnostic testing and more advanced balance rehabilitation.
2.2. Limits of Stability - LOS
The LOS protocol quantifies impairments in ability to intentionally displace the COG to the
patient’s stability limits without losing balance. The patient performs the task while viewing a
real-time display of their COP position in relation to targets placed at the center of the base
of support and at the stability limits (Figure 6). For each of eight directions, the test
measures movement reaction time, movement velocity, movement distance, and movement
directional control. For each of eight trials, the patient, on command, moves the COP cursor
as quickly and accurately as possible towards a second target located on the LOS perimeter,
set at 100% of the theoretical limits of stability, and then holds a position as close to the
target as possible. The patient is allowed up to 8 seconds to complete each trial.
Figure 6 –Interface of LOS protocol.
This protocol is appropriate for:
•Older adults with mobility impairments;
•Athletes interested in rapid ‘off the block’ reactions and direction changes;
•Patients with peripheral neuropathic disorders: diabetes, polyneuropathy;
•Patients with central nervous system pathologies:
oDegenerative diseases: Parkinson’s disease, multiple sclerosis;
oAcquired paralysis and paresis: stroke, brain injury.
The 8 directions of the protocol are: front, front/right, right, back/right, back, back/left, left and
front/left. The distances of the limits of stability are calculated according to the height of the
patient's center of gravity. These distances are calculated for 100% LOS, i.e. 8° left, right
and front, and 4.5° back (see Figure 7).

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Figure 7 –Theoretical boundaries of the limits of stability.
At the end of the protocol appears the trace of the pressure center and the following data
can be saved and exported as a clinical report (Figure 8):
Data
Description
Reaction time
Time between the indication to move (2 seconds after clicking
the Start button Time the color of the point changes) and the
first movement of the patient, in seconds
Mean reaction time per cartesian
axis
Mean reaction time per cartesian axis (front, right, back and left)
Movement velocity
Distance traveled by the center of pressure, between 5% and
95% of the first attempt, divided by 8 seconds (°/s).
Mean movement velocity per
cartesian axis
Mean movement velocity per cartesian axis
Endpoint excursion
Distance from the first attempt to reach the orange dot,
expressed as a percentage of LOS. The end of the first attempt
is considered the point at which the initial movement towards
the goal ceases
Endpoint excursion per cartesian
axis
Mean endpoint excursion per cartesian axis
Maximum excursion
Maximum distance reached during 8 seconds, expressed as a
percentage of LOS
Maximum excursion per
cartesian axis
Mean maximum excursion per cartesian axis
Directional control
Percentage of movement in the intended direction minus off-
axis movement during the first attempt
Directional control per cartesian
axis
Mean directional control per cartesian axis

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Figure 8 –Example of the results section for the LOS clinical report.
Normal Response (indicated by green): Performance within age-matched normative range is
indicative of good voluntary motor control and adequate lower extremity proprioception,
range of motion, and strength for mobility.

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Abnormal Response (indicated by red): Abnormal performance is representative of a
voluntary motor impairment. This can be a result of factors including:
•Biomechanics (range, strength);
•Sensory awareness;
•Central movement disorders;
•Perception (fear).
Clinical Significance: Provides information regarding voluntary motor control for safe and
independent function in all activities of daily living (ADLs).
Ability to voluntarily move the COG to positions within the LOS is fundamental to mobility
tasks such as reaching for objects, transitioning from a seated to standing position (or
standing to seated), and walking.
Reaction time delays are commonly associated with difficulties in cognitive processing
and/or motor diseases. Reduced movement velocities are indicative of high level central
nervous system deficits such as Parkinson’s disease and age-related disorders. Inability to
reach targets in single movements, such as reduced endpoint excursions or excessively
larger maximum excursions and poor directional control are indicators of motor control
abnormalities. Excursions may be restricted by biomechanical limitations. Dizzy and/or
unsteady patients and those fearful of falling may artificially restrict their excursions, while
the strength of those with lower extremity weakness may be insufficient to attain and/or
maintain stable target positions.
Limitations in the LOS may correlate to risk for fall or instability during weight shifting
activities such as leaning forward to take objects from a shelf, leaning back for hair washing
in the shower, or opening the refrigerator door. Patients with reduced stability limits in the AP
direction tend to take smaller steps during gait, while laterally reduced limits can lead to
broad-based gaits.
2.3. Rhythmic Weight Shift - RWS
Use the Rhythmic Weight Shift protocol to evaluate the transfer capacity of the center of
pressure rhythmically in the sagittal and anteroposterior plane, at three different velocities:
slow (3s), moderate (2s) and fast (1s). This protocol measures the velocity in the axis and
the movement control between two targets at 50% of patient’s LOS (Figure 9).
Figure 9 - Interface of RWS protocol for the two planes: sagittal and anteroposterior.

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During performance of each task, the patient views a real time display of their COP position
relative to a target moving (gray ball) at the desired pace and amplitude. The patient has to
reach the gray ball, which is in motion, and control the load transfer at same pace as the
gray point. The patient must change direction when reaching the blue line, at the same time
of the beep signal. For each direction and pace, the RWS measures movement velocity and
directional control.
Appropriate for patients with:
•Central Nervous System Pathologies:
oDegenerative diseases: Parkinson’s disease, multiple sclerosis;
oAcquired paralysis and paresis: stroke, brain injury;
•Peripheral Neuropathic Disorders:
oDiabetes, polyneuropathy;
•Inability to perform the LOS even after instruction and attempt. The RWS then
becomes the voluntary movement test of choice.
At the end of the protocol the pressure center trace for each of the tests, in the sagittal and
anteroposterior directions, at the three speeds mentioned appears (Figure 10). These
images also appear in the clinical report, such as the following data (Figure 11):
Data
Description
On-axis velocity
COP movement velocity along the specified direction (°/s)
Composite on-axis velocity
Mean velocity at the three speeds
Directional control
Percentage of movement in the desired direction minus
off-axis movement
Composite directional control
Mean directional control at the three speeds
The normative values for each variable are presented next to the results.
Figure 10 –Example of the trace of the COP for the two directions at the three speeds tested.

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Figure 11 –Example of the results section for the RWS clinical report.
Normal Response (indicated by green): Subjects attain the required average velocities set
by the pacing target and cover the full distance between the specified movement boundaries
(50% LOS) with good directional control.
Abnormal Response (indicated by red): Patients with motor disorders disrupting normal
timing of movement control may exhibit slower than normal movement velocities, poor
directional control, or a combination of these two problems.
Clinical Significance: Provides information regarding a patient's effective timing of motor
control for basic safety in performance of activities of daily living (ADLs) and gait weight
transfer.
Normal individuals attain the required average velocities by maintaining the rhythm set by
the pacing target and by covering the full distance between the specified movement
boundaries. At the same time, their movements are straight and well coordinated, with
motions in the off-axis direction being a small percentage of the on-axis motion. Functional
consequences include an inability to meet the timing demands of the environment, such as
crossing the street and stepping onto elevators/escalators. Instability may result when
performing activities that require rapid movement speeds, variability in speeds, or changing
directions. Rhythmic, reciprocal movement patterns are required in many high level athletic
and leisure interests.
2.4. Weight Bearing/Squat - WBS
The WBS protocol quantifies the patient’s ability to perform squats with the knees flexed at
30°, 60°, and 90°, while maintaining equal weight on the two legs (Figure 12). In the erect
position, most body weight is borne through the skeletal system, and relatively less stress is
placed on the knee and hip joints. Increasing depths of squat place greater stress on the
knees and hips, making these positions more sensitive in detecting weight-bearing
abnormalities related to lower extremity musculoskeletal injuries.

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Figure 12 - Interface of WBS protocol with the various angles of knee flexion: 0º, 30º, 60º and 90º.
This protocol allows observation of weight distribution in the sagittal plane with the patient
standing up with different knee flexion angles.
At the end, a graph with the percentage of body weight of the patient on each side (left and
right) with knees straight (at 0°) and with knees bent at 30°, 60° and 90° appears. It is also
possible to save this data and generate a clinical report (Figure 13).
Data
Description
Percentage of body weight
Percentage of weight on each side of the sagittal plane, for each
angle of knee flexion
Figure 13 –Example of the results section for the WBS clinical report.
Normal Response (indicated by green): Normal individuals maintain body weight within ±7%
of equal on the two legs over the full range of squatting positions.
Abnormal Response (indicated by red): Reduced weight bearing on one leg may reflect
sensory (proprioceptive) or strength loss, reduced range of motion, and/or pain. Bending,
stooping and squatting positions substantially increase stress on the ankles and knees, and
may identify weight-bearing differences not detectable in a less challenging (fully erect)
position.

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Clinical Significance: Provides information regarding the symmetry of the patient's voluntary
motor control for basic safety in performance of activities of daily living (ADLs), sports or
leisure activities.
Patients with lower extremity orthopedic injuries may exhibit equal weight bearing in the
erect position, but will bear a preponderance of weight on the uninvolved side during more
stressful squatting positions. Patients with generalized or unilateral weaknesses will
demonstrate impaired motor control for sit-to-stand transitions or an inability to safely
retrieve objects from the floor. In the athletic population, impairments may result in reduced
readiness to move side-to-side or accuracy of weight shift or thrust during squat-to-extend
movements.
2.5. Unilateral Stance - US
The US assessment quantifies the patient’s ability to maintain postural stability while
standing on one leg at a time with the eyes open and closed (Figure 14). The US enhances
the observational testing of single leg stance performance by providing an objective measure
of patient sway velocity for each of the four task conditions. The length of each trial is ten
seconds.
The US is highly sensitive, but not specific because a large number of independent factors
can impact performance. A partial list of these factors includes lower extremity strength and
weight bearing control, sensory balance control, movement strategies, and prior practice
with the task.
Use this protocol to measure the balance in four conditions: left foot lifted up with eyes open,
left foot lifted up with eyes closed, right foot lifted up with eyes open and right foot lifted up
with eyes closed. This protocol also allows to evaluate the difference of oscillation (in
percentage) between the left and right side with the eyes opened and closed.
Figure 14 - Interface of US protocol, for left and right foot, respectively.
At the end, the following results are presented for each of the indicated conditions, in the
form of graphs (Figure 15).

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Data
Description
Trial time
Elapsed time: 10 seconds. In the case of loss of equilibrium, appears
the time until the fall has occurred
Sway velocity
Distance traveled by the center of pressure divided by the test time
(°/s). If a fall occurs the value is 6 °/s
Mean sway velocity
Mean sway velocity for each condition
Sway velocity difference
Sway velocity difference (in percentage) between left and right side
with eyes open and closed. The bar points to the side with better
performance
In the clinical report can be observed the pressure center trace for each test, as well as the
graphs with the aforementioned data. The normative values for each variable are presented
below the results.
Figure 15 –Example of the results for the US protocol.
Normal individuals have significantly more sway standing on one foot versus two, and even
more sway on one foot with eyes closed. Patients who become unstable may have difficulty
using visual or somatosensory information for balance control, and/or may have
musculoskeletal problems that make it difficult to compensate. Functional consequences are
significant for performance of activities that require single-leg balance, such as donning
pants or hosiery, ascending or descending elevations, or navigating narrow support
surfaces, such as ladders and scaffolding.
2.6. Fall Risk - FR
Falls are a common occurrence among older people, even for those in good health and with
no apparent balance problems. Fall Risk test allows identification of potential fall candidates.
Test results are compared to age-dependent normative data. Scores higher than normative
values suggest further assessment for lower extremity strength, proprioception, and
vestibular or visual deficiencies. The quantification of the patient’s postural sway velocity can
be used to predict risk. Velocity can be described as the speed of an individual's sway as
balance is maintained. Higher velocities, when cues are given to specifically stand as
motionless as possible, are suggestive of postural control deficits. The Fall Risk test protocol

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(Figure 16) is based on research from the University of Dayton (Bigelow KE and Berme N.
2011. ‘Development of a protocol for improving the clinical utility of posturography as a fall-
risk screening tool’J Gerontol A Biol Sci Med Sci 66A: 228–233) and the University of
Jyväskylä in Finland (Pajala, S. et al. 2008. ‘Force platform balance measures as predictors
of indoor and outdoor falls in community-dwelling women aged 63-76 years’J Gerontol A
Biol Sci Med Sci 63A:171–178).
Figure 16 - Interface of Fall Risk protocol, for comfortable and narrow stance.
Use this protocol to measures the static balance in four conditions:
1. Comfortable stance with eyes open;
2. Comfortable stance with eyes closed;
3. Narrow stance with eyes open;
4. Narrow stance with eyes closed.
After performing all the conditions of the protocol, the value of the sway velocity index for
each of the conditions appears. This sequence of tests can provide a fall risk prediction.
At the end of the protocol, it is possible to save the following data and generate a clinical
report.
Data
Description
Velocity
Distance traveled in the sagittal plane divided by the test time, 45
seconds (mm/s)
Composite velocity
Mean velocity for all conditions
Sway velocity index (SVI)
Value based on the velocity and height of the patient, normalized
by the natural logarithm function
Composite SVI
Mean SVI for all conditions
Z-Score
Number of standard deviations of the SVI from the mean value
indicated in the normative values
Composite Z-Score
Mean Z-Score for all conditions
In the clinical report (Figure 17) can be observed the pressure center trace for each
condition. The normative values for each condition are presented next to the results. The
color of the bar will be green, yellow or red depending on the result, higher values will be red
(meaning less stable) and lower values than normative values will be green.

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Figure 17 –Example of the results section for the FR clinical report.