1274.full

Research Report

Sensory-Specific Balance Training in
Older Adults: Effect on Proprioceptive
Reintegration and Cognitive Demands
Kelly P Westlake, Elsie G Culham
KP Westlake, PT, PhD, MSc, is
Post-Doctoral Fellow, Rehabilita-
tion Research and Development
Background and Purpose
Center, VA Palo Alto HCC, 3801 Age-related changes in the ability to adjust to alterations in sensory information
Miranda Ave, Palo Alto, CA 94304 contribute to impaired postural stability. The purpose of this randomized controlled
(USA). Address all correspondence trial was to investigate the effect of sensory-specific balance training on propriocep-
to Dr Westlake at: westlake@rrd.
stanford.edu.
tive reintegration.

EG Culham, PT, PhD, is Professor Subjects
and Director, School of Rehabilita-
tion Therapy, Queen’s University, The subjects of this study were 36 older participants who were healthy.
Kingston, Ontario, Canada.

[Westlake KP, Culham EG.
Methods
Sensory-specific balance training Participants were randomly assigned to a balance exercise group (n 17) or a falls
in older adults: effect on proprio- prevention education group (n 19). The primary outcome measure was the center-
ceptive reintegration and cogni- of-pressure (COP) velocity change score. This score represented the difference
tive demands. Phys Ther.
2007;87:1274 –1283.]
between COP velocity over 45 seconds of quiet standing and each of six 5-second
intervals following proprioceptive perturbation through vibration with or without a
© 2007 American Physical Therapy secondary cognitive task. Clinical outcome measures included the Fullerton Ad-
Association
vanced Balance (FAB) Scale and the Activities-specific Balance Confidence (ABC)
Scale. Assessments were conducted at baseline, postintervention, and at an 8-week
follow-up.

Results
Following the exercise intervention, there was less destabilization within the first 5
seconds following vibration with or without a secondary task than there was at
baseline or in the falls prevention education group. These training effects were not
maintained at the 8-week follow-up. Postintervention improvements also were seen
on the FAB Scale and were maintained at follow-up. No changes in ABC Scale scores
were identified in the balance exercise group, but ABC Scale scores indicated
reduced balance confidence in the falls prevention education group postintervention.

Discussion and Conclusion
The results of this study support short-term enhanced postural responses to propri-
oceptive reintegration following a sensory-specific balance exercise program.

Post a Rapid Response or
find The Bottom Line:
www.ptjournal.org

1274 f Physical Therapy Volume 87 Number 10 October 2007

Balance Training in Older Adults

P
ostural control depends on the sensory environments, result in in- strate reduced postural destabiliza-
ability to extract peripheral sen- creased postural stability compared tion and earlier restabilization imme-
sory inputs, integrate this infor- with the effects of nonspecific activ- diately following the termination of
mation within the central nervous ity interventions, such as running or proprioceptive perturbation through
system (CNS), and coordinate and strength training, lend support to vibration in comparison with pre-
execute an appropriate motor re- this theory.11–13 exercise outcomes or with the out-
sponse. Proprioception is an essen- comes in a falls prevention educa-
tial component of this sequence of One method used to evaluate the tion group. These effects were
events, providing orientation infor- contribution of proprioceptive in- postulated to improve during a con-
mation about passive and active puts to postural control and the in- comitant cognitive task. The second-
movements and positions of the tegrity of the integrative mechanisms ary hypothesis was that the en-
joints as well as the force resulting within the CNS is to measure hanced postural stability would be
from muscular contractions. Age- changes in postural sway during or reflected in superior scores on a bal-
related changes in the ability to as- following vibration applied over the ance performance scale and a
sess the contribution of propriocep- muscle belly or tendon.14 This tech- balance confidence questionnaire.
tive inputs relative to those of other nique directly targets the primary
sensory inputs become evident un- muscle afferents contributing to pro- Method
der conditions in which the propri- prioception and may effectively re- Study Participants and
oceptive inputs are distorted or dis- flect a perturbation of this system. Study Design
torted and then suddenly restored.1 Participants were volunteers over 65
Whereas young adults who are Muscle vibration evokes a sensation years of age who were healthy and
healthy are able to restore balance of movement in a direction that nor- recruited through advertisements
quickly by taking advantage of sen- mally would cause elongation of the and flyers in the community. Exclu-
sory redundancy and centrally re- vibrated muscle. Accordingly, vibra- sion criteria were pre-existing major
weighing available information,2– 4 tion of antagonistic muscle groups lower-extremity pathology (eg,
older adults do not as readily inter- results in immediate disruption of chronic ankle instability or severe
pret misleading cues or recognize the proprioceptive system.3 Postural osteoarthritis), neurological disor-
and reintegrate accurate propriocep- responses to such a perturbation ders or balance difficulties (eg, ver-
tive information and therefore can then can be assessed in a quiet stand- tigo, poor vision, dizziness, stroke,
experience postural instability.3,5 ing position by recording center-of- or epilepsy) that would prevent
These effects are particularly evident pressure (COP) outcomes on a force standing for the duration of the test-
when attentional resources are platform.3,15 This position effectively ing procedures without the aid of an
divided.3,6 – 8 reduces confounding variables, such assistive device, and health condi-
as muscle activation, torque genera- tions (eg, heart disease, uncontrolled
Given that the sensory inputs related tion, and biomechanical changes, hypertension, chronic obstructive
to various environmental conditions that are present during more dy- pulmonary disease, or osteoporosis)
are constantly changing,9 the ability namic tasks. Such variables inevita- that would preclude participation in
to adjust instantly to a change in sen- bly would become a source of accu- a balance exercise program.
sory information is central to the re- rate proprioceptive information that
duction of fall risk in older adults.10 could override the controlled effect A brief clinical examination was used
To date, there have been no reports of proprioceptive perturbation at the to screen for symptoms of peripheral
of training interventions designed to ankle joints. Because the present neuropathy, which are considered a
enhance the ability of older adults to study represents one of the earliest risk factor for falls.16 This examina-
use proprioceptive information in reports on the ability to train sensory tion identified the presence, diminu-
balance control. The successful iden- integration immediately following vi- tion, or absence of sensation to light
tification of training effects necessar- bration perturbation, the quiet stand- touch on the dorsal and plantar as-
ily involves a randomized controlled ing protocol was considered advan- pects of the foot, the Achilles tendon
trial with an exercise intervention tageous as a means to isolate changes reflex, and position sensation of the
designed to induce specific changes in this ability. big toe. Subjects demonstrating the
in the recognition and effective use absence or diminution of one or
of sensory information. Findings that Thus, the primary hypothesis of the more of these characteristics were
sensory-specific balance exercises, present study was that older adults, excluded from participation. Physi-
such as training on unsteady support having completed a sensory-specific cian approval was required before
surfaces with transitions between exercise program, would demon- the subjects were allowed to partic-

October 2007 Volume 87 Number 10 Physical Therapy f 1275


together position. Progressions to
these tasks included simultaneous
alterations of visual and vestibular
inputs. To alter visual cues, partici-
pants were instructed to close their
eyes, to engage vision with a reading
or tracking secondary task, or to per-
form balance tasks with a distracting
background, such as a checked pat-
tern or moving people. To modify
vestibular cues, participants were in-
structed to tilt their head backward
or to quickly move their head side to
side and up and down.

Measurement of Central
Integration and Attentional
Capacity
The mean COP velocity for the total
COP path length was measured on a
force platform* as an estimate of the
Figure 1. frequency of postural corrections.
Experimental setup of the vibrators at the Achilles and tibialis anterior tendons. Par- Of the COP stability parameters,
ticipants stood as steadily as possible with arms alongside the body, heels positioned
COP velocity generally is considered
according to height, and forefeet splayed to a comfortable stance.
to be most useful in identifying age-
related changes and fall risk.18 –20
The mean velocity also demon-
ipate in the exercise program. All by participants in the exercise group strated the highest sensitivity to the
subjects gave written informed con- and the education group were 21.5 effects of vibration on posturo-
sent prior to data collection. (89.9%) and 5.4 (66.3%), respec- graphic measurements21 and had the
tively. The 36 participants who com- smallest reproducibility error (intra-
In this single-blind, randomized con- pleted the exercise (n 17) and individual standardized coefficient of
trolled trial, participants were as- education (n 19) interventions re- variation of 14) over a 1-week
signed to an exercise group or a falls turned for postintervention testing. period.20
prevention education group. Both By the 8-week follow-up, conducted
groups were assessed at baseline only with the exercise group, 15 par- Data were sampled at 200 Hz and
and within 1 week postintervention. ticipants returned for testing. smoothed with a fourth-order
Follow-up testing was done for the double-pass Butterworth filter with a
exercise group only at 8 weeks Sensory-specific balance classes cutoff frequency of 10 Hz. Proprio-
postintervention. were held 3 times per week, for 1 ceptive input was perturbed by use
hour each session, over an 8-week of 4 vibrators oscillating at 80 Hz, 1
Of the 64 older adults who re- period. The exercise protocol fol- mm in amplitude,2,22 and secured at
sponded to study advertisements, 44 lowed the FallProof Program,17 both ankles with 3-cm-wide elastic
met study criteria and were random- which emphasizes static and dy- bands (Fig. 1).
ized into the exercise or education namic balance exercises with transi-
group. Eight participants dropped tions between different sensory con-
The COP velocity was measured for
out of the study for reasons such as ditions. Activities were designed to
each of the 45-second postural con-
time commitment issues, lack of optimize and force use of the so-
ditions shown in Table 1, completed
transportation, language barrier, and matosensory system. Tasks included
as one set in a random order, fol-
disinterest. By the end of the 8-week standing or walking on various sup-
lowed by 3 minutes of seated rest.
interventions, 17 and 19 participants port surfaces, such as a rocker board,
remained in the exercise and educa- foam, or narrow beam, and standing
tion programs, respectively. The in a tandem position, a semitandem * Biodex Medical Systems Inc, 20 Ramsay Rd,
mean numbers of all visits attended position, on one leg, or in a feet- Shirley, NY 11967.



Three sets were performed, and the Table 1.
average of 3 trials was recorded for Postural Conditions Used to Evaluate Proprioceptive Reintegration With or Without a
each condition. Conditions 3 and 4 Secondary Task
included 5 seconds of stable stand- Testing Description
ing followed by 10 seconds of vibra- Conditiona
tion activation3,21 and then 30 sec- 1 Quiet standing, eyes closed
onds of deactivation. The initial 5
2 Quiet standing, eyes closed, secondary task
seconds was used so that partici-
pants could become acclimated to 3 Quiet standing, eyes closed, vibration
standing on the force platform prior 4 Quiet standing, eyes closed, vibration, secondary task
to the onset of vibration. The third, a
The duration of each condition was 45 seconds.
30-second interval was used because
previous work had indicated that 10
seconds was insufficient for com-
responsiveness of the FAB Scale fol- ence of strength (force-generating
plete recovery of postural stability in
lowing an exercise intervention had capacity) between and within
the absence of vision in either a
not yet been established. groups. Following one practice trial,
young or an older population.3 The
an average of the best 3 of 5 peak
COP velocity was analyzed over
The Activities-specific Balance Confi- torque values normalized to body
5-second intervals from the moment
dence (ABC) Scale was used to assess weight was recorded.
the vibration was turned off, at 15.05
participants’ level of balance confi-
to 20 seconds (time 1), 20.05 to 25
dence in performing particular Data Analysis
seconds (time 2), 25.05 to 30 sec-
tasks.24 Confidence in performing The effects of the interventions on
onds (time 3), 30.05 to 35 seconds
each task was rated on a scale of 0 the ability of older adults to regain
(time 4), 35.05 to 40 seconds (time
(no confidence) to 10. The ABC postural stability with or without a
5), and 40.05 to 45 seconds (time 6).
Scale showed excellent internal con- secondary task were assessed by use
For the secondary task in conditions
sistency (Cronbach alpha .96), test- of a group time interval visit
2 and 4, participants counted back-
retest reliability (r .92), and validity (2 6 2) analysis of variance
ward by 3 from a random 3-digit
for community-dwelling older (ANOVA) for repeated measures on
number as quickly and accurately as
people.24,25 the last 2 factors. The dependent
possible throughout the 45-second
variable was COP change scores, ob-
trials.7
The Physical Activity Scale for the tained by subtracting COP velocity
Elderly (PASE) was used to deter- averaged over 3 trials for each time
Clinical Measures
mine group equivalences in activity interval of conditions 3 and 4 from
The Fullerton Advanced Balance
levels outside of the treatment inter- the average COP velocity in the three
(FAB) Scale was used to measure
vention. Scores ranged from 0 to 45-second trials in conditions 1 and
functional limitations associated
greater than 400, depending on sub- 2, respectively. The equivalences of
with 10 high-level balance tasks in-
jects’ reported activity intensities COP velocity across the six 5-second
corporating tests that challenge sen-
and frequencies over 7 days. The intervals and over the entire 45-
sory integration.23 The FAB Scale
PASE showed good test-retest reli- second time interval during condi-
included modified clinical tests for
ability (r .75) and validity for older tion 1 were verified by use of data
sensory integration in balance: walk-
subjects who were healthy.26,27 from 10 randomly selected partici-
ing with head turns, Functional
pants (F 0.37; df 6,54; P .76).
Reach Test, 360-degree turn, tandem
The concentric isokinetic strength of Changes in strength and clinical mea-
walking, one-leg stance, 2-foot jump,
the hip, knee, and ankle flexor and sures were determined by use of a
step up and over, and reactive pos-
extensor muscles of the dominant group visit (2 2) repeated-
tural control. Scores ranged from 0
leg was assessed by use of an isoki- measures ANOVA for continuous
(unable) to 4, with a maximum score
netic dynamometer (AMTI Multiaxis variables or a Friedman test for cate-
of 40. Psychometric testing of this
Force Platforms, model OR 6-7)† set gorical variables.
scale indicated good convergent va-
at a velocity of 60°/s. These measure-
lidity compared with the Berg Bal-
ments were taken in consideration of The outcomes for the exercise group
ance Scale ( .75) and demon-
the potentially confounding influ- at the 8-week follow-up were com-
strated high test-retest ( .96),
pared with the outcomes at baseline
intrarater ( .97–1.00), and inter- †
Advanced Medical Technologies Inc, 176 and postintervention by use of a
rater ( .94 –.97) reliability.23 The Waltham St, Watertown, MA 02172.



A less destabilization occurring in the
COP Velocity Change (cm/s) 4.0 exercise group (change score
3.5 Exercise Group [X SD], 1.31 0.91 cm/s) than in
* Education Group the education group (2.00 1.05
3.0
cm/s) postintervention (Fig. 2A).
2.5
Separate analysis of the exercise
2.0 group revealed a visit time inter-
1.5 action (F 8.62; df 5,80; P .001),
1.0 indicating training effects on both
0.5 the time to restabilize and the
* amount of destabilization (Fig. 3A).
0.0
-0.5 Change scores began to stabilize dur-
-1.0 ing time interval 4 at baseline and
1 2 3 4 5 6 during earlier time interval 3 postin-
Time Interval tervention. A reduction in the extent
of destabilization was indicated by a
B significant decrease in change scores
4.0 from baseline to postintervention
COP Velocity Change (cm/s)

3.5 Exercise Group during time interval 1 (2.23 1.18
Education Group versus 1.31 0.91 cm/s) (P .002),
3.0
* with a trend toward significance dur-
2.5 ing time interval 2 (0.72 0.76 versus
2.0 0.43 0.52 cm/s) (P .081). Analysis
1.5 of the education group revealed a
1.0 nonsignificant visit time interac-
tion (F 0.42; df 5,90; P .70), indi-
0.5
* cating no change in the ability to
0.0 stabilize following vibration.
-0.5
-1.0 The COP change scores for the ex-
1 2 3 4 5 6 ercise group were different postin-
Time Interval tervention (1.31 0.91 cm/s) and at
Figure 2. the 8-week follow-up (2.11 1.50
Change in center-of-pressure (COP) outcomes following vibration in exercise and cm/s) during time interval 1
education groups postintervention (X SD). (A) COP sway velocity change score fol- (P .029), suggesting that postinter-
lowing vibration perturbation. (B) COP sway velocity change score following vibration vention improvements were not
perturbation and while performing a secondary task. *Significant difference between maintained. No differences were
groups (P .044).
identified between baseline (2.29
1.19 cm/s) and the 8-week follow-up
(P 1.00).
repeated-measures ANOVA or a Results
Friedman test with visit as the Proprioceptive Reintegration Quiet standing with vibration
within-subject factor. Significant in- Quiet standing with vibration and secondary task (condition 4).
teraction effects (P .05) were ana- (condition 3). The first objective The second objective of this study
lyzed with Bonferroni-adjusted post of this study was to examine postural was to examine postural stability fol-
hoc tests. Statistical procedures were recovery following vibratory pertur- lowing vibratory perturbation during
performed with SPSS, version 11.5.‡ bation without a secondary task. A secondary task performance. One
visit time group interaction was outlier in the education group was
identified (F 3.82; df 5,170; identified as having a mean change
P .019). Group differences were score greater than 3 standard devia-
found only during time interval 1 tions above the group mean and was
‡
SPSS Inc, 233 S Wacker Dr, Chicago, IL (F 4.36; df 1,35; P .044), with excluded from subsequent analysis.
60606. A visit time group interaction



was revealed (F 3.13; df 5,165; A
P .018). 4.0

3.5 *† Baseline
Analysis of group differences for
each time interval across baseline 3.0 Postintervention
and postintervention visits indicated 2.5
a difference in the extent of desta- 2.0
bilization during time interval 1
†
1.5
(F 4.90; df 1,34; P .034) post- 1.0
intervention, with lower mean † †
change scores in the exercise group 0.5
*‡
(1.12 0.58 cm/s) than in the educa- 0.0
tion group (1.71 0.85 cm/s) -0.5 ‡
(Fig. 2B). Separate analysis of the ex-
‡
-1.0
ercise group revealed a visit time 1 2 3 4 5 6
interaction (F 5.76; df 5,80; Time Interval
P .001) (Fig. 3B). No improvements
in the time to stabilize were noted.
Further analysis of change scores be- B
4.0

tween baseline and postintervention 3.5 Baseline
as a function of each time interval
3.0 *† Postintervention
revealed a difference during time in-
terval 1 (P .002). This finding con- 2.5
firmed that there was less destabili- 2.0
zation during the 5 seconds 1.5 †
immediately following vibration as a 1.0 †
result of the exercise intervention.
0.5
Analysis of the education group re- *‡
vealed a nonsignificant visit time 0.0
interaction (F 1.27; df 5,85; -0.5 ‡ ‡
P .30). -1.0
1 2 3 4 5 6
The inclusion of the 8-week Time Interval
follow-up change scores for the ex- Figure 3.
ercise group revealed a visit time Change in center-of-pressure (COP) outcomes following vibration at baseline and
interaction (F 2.93; df 10,140; postintervention in exercise group (X SD). (A) COP velocity change scores following
P .012), with higher change scores vibration perturbation. (B) COP velocity change scores following vibration perturbation
and while performing a secondary task. *Significant difference between baseline and
at the 8-week follow-up (2.05
postintervention (P .006). †Significant difference between baseline time intervals
1.47 cm/s) than postintervention (P .025). ‡Significant difference between postintervention time intervals (P .001).
(1.14 0.61 cm/s) during time inter-
val 1 (P .023). These results further
support the fact that improvements Clinical Measures postintervention and at follow-up
in the ability to stabilize after the Means and standard deviations for were maintained. Specific details re-
exercise intervention were not clinical measures are shown in Table garding changes in the mean and
maintained. 3. In terms of the FAB Scale, the standard deviation of each FAB Scale
Friedman test revealed differences item are shown in Table 4. Post hoc
The response accuracy and speed of between visits in the exercise group analysis revealed differences be-
performance of the secondary task ( 2 16, P .001). Post hoc analysis tween baseline and postintervention
are shown in Table 2. No differences revealed differences between base- for items 6 (one-leg stance), 7 (stand-
were identified between groups, nor line and postintervention total ing on foam), and 9 (walking with
was there a group visit interaction. scores (P .001) and between base- head turns) and differences between
line and 8-week follow-up total baseline and the 8-week follow-up
scores (P .001), suggesting that the for item 9 (Bonferroni-adjusted P
improvements in functional balance value of .025).



Table 2.
Accuracy and Speed of Backward Counting by 3 During Condition 4a

Parameter X SD for the Following Group:
Baseline Postintervention 8-wk
Follow-up
Exercise Education Exercise Education Exercise
Accuracy (no. of correct responses/total no. of 0.94 0.093 0.96 0.035 0.95 0.06 0.97 0.05 0.94 0.06
responses)
Speed (no. of responses/s) 0.41 0.13 0.44 0.16 0.47 0.16 0.47 0.15 0.43 0.19
a
Condition 4 quiet standing, eyes closed, vibration, secondary task.

Regarding the PASE scores, no differ- group visit interaction (P .44) Although it may be argued that en-
ences were identified between were identified, thereby supporting hanced signals arising at the level of
groups or visits at baseline or postint- group equivalences at baseline and the proprioceptive receptors may
ervention; significantly lower scores postintervention. account for the postural improve-
were found in the exercise group at ments, we recently demonstrated
the 8-week follow-up than postinter- Discussion that this mechanism is not likely to
vention (P .003). Interestingly, a The results of the present study ap- be the substrate for change.30 With
Pearson correlation analysis between pear to support the original hypoth- only 1 of 3 proprioceptive measures
PASE scores and time interval 1 for esis that the ability of older adults indicating improvements with train-
conditions 3 and 4 revealed no rela- to reintegrate proprioceptive inputs ing in our previous work, it was dif-
tionships (r .16, P .13, and r is augmented following sensory- ficult to ascribe a training effect at
.06, P .57). specific training, and this effect is the peripheral level. However, with-
not likely to be attributable to an out sufficient physiological evidence
For the ABC Scale questionnaire, a increase in lower-extremity strength from receptor isolation techniques,
group visit interaction was identi- or activity level. Although a few stud- such as microneurography,14 the
fied (F 4.27; df 1,34; P .047), ies reported training effects on pos- possibility of an increase in the dis-
with a lower balance confidence tural stability when proprioceptive charge of these receptors cannot be
score postintervention than at base- input was reduced,28,29 an improved discounted.
line only for the education group ability of older adults to recognize
(F 4.56; df 1,18; P .047). and use the restoration of accurate A more probable explanation for
proprioceptive information had not these results is an increase during
In terms of strength at the hip, knee, previously been documented. the training intervention in the atten-
and ankle, no main effect of group tion allocated to proprioceptive cues
(P .66) or visit (P .072) and no (explicit learning), which eventually

Table 3.
Clinical Measures for Exercise and Education Groups at Baseline, Postintervention, and 8-Week Follow-up

Clinical Measurea X SD Score for the Following Group:
Baseline Postintervention 8-wk
Follow-up
Exercise Education Exercise Education Exercise
b,c b
FAB Scale 31 5 32 8 35 4 33 8 35 5c
PASE 102.4 45.0 99.1 44.0 127.3 57.6d 101.6 51.4 79.5 24.9d
ABC Scale 84.8 9.3 87.5 10.7e 85.7 9.5 79.1 24.2e 85.0 9.7
a
ABC Activities-specific Balance Confidence, FAB Fullerton Advanced Balance, PASE Physical Activity Scale for the Elderly.
b
Significant difference between baseline and postintervention FAB Scale scores (P .001).
c
Significant difference between baseline and 8-week follow-up FAB Scale scores (P .02).
d
Significant difference between postintervention and 8-week follow-up PASE scores for exercise group (P .003).
e
Significant difference between baseline and postintervention ABC Scale scores for education group (P .047).



Table 4.
Mean ( SD) and Friedman Mean Rank for Scores on the Fullerton Advanced Balance (FAB) Scale for the Exercise Group

FAB Scale Item Baseline Group Postintervention 8-Week Follow- P
Group up Group
X SD Mean X SD Mean X SD Mean
Rank Rank Rank
1. Stand with feet together, eyes closed 4 0 1.9 4 0 2.0 4 0 2.0 .39
2. Forward reach 4 1 1.9 4 0 2.1 4 1 1.9 .26
3. 360° turn 3 1 1.8 3 1 1.9 4 1 2.3 .05
4. Step up and over 4 0 1.9 4 0 2.0 4 0 2.0 .37
5. Tandem walk 3 1 1.8 4 1 2.3 3 1 1.9 .14
a a
6. One-leg stance 3 1 1.6 3 1 2.2 3 1 2.2 .02b
7. Stand on foam, eyes closed 3 1 1.7a 4 0 2.2a 4 0 2.0 .02b
8. 2-foot jump 3 1 1.8 3 1 2.1 3 1 2.1 .35
a,c a c
9. Walk with head turns 2 1 1.5 3 1 2.3 3 1 2.2 .01b
10. Reactive postural control 2 1 1.6 3 1 2.2 3 1 2.2 .12
Total score 31 5 1.2a,c 35 4 2.5a 35 5 2.3c .001b
a
Significant difference between baseline and postintervention scores (P .025).
b
Significant difference between testing sessions (P .05).
c
Significant difference between baseline and 8-week follow-up scores (P .025).

led to a less attentionally demanding identified correctly. Thus, a greater postural stability improved or de-
recovery of postural stability (im- extent of cognitive resources was clined relative to baseline perfor-
plicit learning).31 Improvements in necessary for this test than for other mance depending on the cognitive
postural control in the exercise proprioceptive measures, meaning demands of the secondary task.32
group without evidence of reduc- that the possibility of improved at- Perhaps the task of counting back-
tions in the accuracy or speed of the tention cannot be ruled out. Besides ward by 3, used in the present study,
counting task support this theory. As the possible influence of attention in did not represent a sufficiently chal-
the accuracy of peripheral input de- recognizing and selecting proprio- lenging cognitive task to tax atten-
clines with age, attentional resources ceptive information, it also has been tional resources effectively. Never-
become more focused on the control suggested that attention is involved theless, the finding that the extent of
of posture.1 Thus, the introduction in sensory integration under condi- destabilization was reduced postin-
of a sufficiently challenging second- tions of sensory conflict.33 tervention with or without a second-
ary task or postural condition often ary task suggests that either a shift in
results in reduced task performance One surprising outcome was the de- attention or increased attentional ca-
or instability.6,32 Because the specific crease in COP velocity change scores pacity is possible. A follow-up train-
instructions provided to participants (ie, reduced destabilization) during ing study involving a more cogni-
in the present study were to main- secondary task performance relative tively demanding secondary task
tain focus on the secondary task, ev- to the results obtained in the no- under conditions of sensory conflict
idence that stability was increased secondary-task condition (Fig. 2). Al- may bring further clarity to this
suggests an implicit learning effect. though the difference was not signif- discussion.
icant, it was evident in both the
Our previous finding that a velocity exercise and the education groups. Several authors3,4,35 have proposed
discrimination test was the only pro- that the explanation for impaired
prioceptive outcome to improve In contrast, previous studies6,33,34 postural responses in older adults
with exercise also suggests en- demonstrated a destabilizing rather lies in age-related changes in central
hanced central mechanisms.30 This than a stabilizing effect with the ad- integration mechanisms. During the
test required subjects to identify the dition of a secondary task. These exercise intervention in the present
faster of 2 presented velocities until conflicting results may be reconciled study, sensory inputs were manipu-
the smallest velocity difference was by a recent study demonstrating that lated by altering the support surface



or by reducing the sensory redun- bation. This lack of an effect suggests improvements in the FAB Scale
dancy of the visual and vestibular that there are context-dependent dif- scores were maintained in the exer-
systems; these manipulations forced ferences following a targeted train- cise group, it remains unclear
participants to effectively reweigh ing intervention and thereby sup- whether the control group also ex-
remaining inputs within the CNS.17 ports the need for ongoing sensory perienced changes over the 8-week
The direct beneficial consequences training. In turn, compensatory sen- time period. The second limitation is
of these tasks were reflected in the sory mechanisms may be selected that the participants were older
ability of the participants to regain more efficiently under conditions of adults who were healthy rather than
stability, likely by taking advantage sensory deprivation38 or restoration. older adults with balance impair-
of the restored proprioceptive infor- ments, who may have benefited to a
mation and integrating it with vestib- The decrease in balance confidence greater extent. Future research may
ular inputs and other sensorimotor in the education group postinterven- include a group of older adults with
cues. Evidence of similarly enhanced tion may be explained by discussions declining balance to assess the effect
central integration following sensory centered on effective means of of training on central sensory reinte-
training has been found in studies reducing fall risk. An increased gration. Such an investigation also
demonstrating improved stability awareness of these topics may have may include a kinematic and kinetic
during the manipulation of proprio- underscored the apprehension expe- analysis of the effect of vibration on
ceptive, vestibular, or visual systems rienced during functional balance dynamic stability tasks. A combina-
or all of these by use of the Sensory tasks until changes could be imple- tion of findings from these studies
Organization Test (SOT).28,36 Al- mented. Two recent studies examin- and those from the present study
though the use of a sway reference ing the effectiveness of falls preven- may lead to more efficient balance
standing surface during the SOT is tion education reported similar exercise interventions and, ulti-
considered to be a proprioceptive findings, with almost half of the par- mately, to a reduction in fall risk in
perturbation, the muscle spindles ticipants demonstrating increased older adults.
serving this system cannot be tar- fear of falling39 and a 28% increase in
geted as precisely as with vibration. 1 or more falls40 at follow-up. Both authors provided concept/idea/re-
These studies also were limited be- search design, writing, and data analysis. Dr
cause of the use of a cross-sectional Seasonal variations in PASE scores Westlake provided data collection, project
design including seasoned tai chi may account for the reduction in management, fund procurement, and sub-
practitioners36 and the use of the scores at the 8-week follow-up in the jects. Dr Culham provided facilities/equip-
ment and consultation (including review of
SOT for both training and testing exercise group.26 Follow-up testing manuscript before submission).
procedures,28 which may have re- occurred during both the winter and
sulted in a learning effect.37 the summer months, when either This study was approved by Queen’s Univer-
sity Health Science and Affiliated Teaching
snow and ice or high heat and hu- Hospitals Research Ethics Board.
The functional significance of the re- midity may have forced participants
sults of the present research was ev- indoors. Arguably, the reduction in Data from this study were presented at the
International Congress of the World Confed-
ident because of improvements in activity level may explain the lack of eration for Physical Therapy; June 2– 6, 2007;
the FAB Scale scores in the exercise retention in the ability to reintegrate Vancouver, British Columbia, Canada.
group. These results, demonstrating proprioceptive information effec-
Dr Westlake was supported by a Canadian
responsiveness to training, further tively. However, without a signifi- Institutes of Health Research Fellowship.
support the validity of FAB Scale cant correlation between PASE
scores. Interestingly, the items dem- scores and COP velocity in the first 5 This article was received September 7, 2006,
and was accepted May 8, 2007.
onstrating improvements across vis- seconds following vibration, this the-
its were items 6 (one-leg stance), 7 ory is not substantiated. DOI: 10.2522/ptj.20060263
(standing on foam), and 9 (walking
with head turns), each of which Conclusion
comprises an element of sensory in- The results of the present study sug- References
tegration. However, even though gested that sensory-specific exercise 1 Kristinsdottir EK, Fransson PA, Magnusson
M. Changes in postural control in healthy
subjects showed improvements in had a training effect on propriocep- elderly subjects are related to vibration
and maintenance of FAB Scale scores tive reintegration. However, 2 limita- sensation, vision and vestibular asymme-
try. Acta Otolaryngol. 2001;121:700 –706.
at the 8-week follow-up, the im- tions should be mentioned. The first 2 Hay L, Bard C, Fleury M, Teasdale N. Avail-
provements did not translate to the limitation is that 8-week follow-up ability of visual and proprioceptive affer-
maintenance of enhanced postural scores were not obtained for the ed- ent messages and postural control in el-
derly adults. Exp Brain Res. 1996;
stability following vibratory pertur- ucation group. Therefore, although 108:129 –139.



3 Teasdale N, Simoneau M. Attentional de- 16 Richardson JK, Ashton-Miller JA. Periph- 29 Tsang WW, Hui-Chan CW. Effect of 4- and
mands for postural control: the effects of eral neuropathy: an often-overlooked 8-week intensive Tai Chi training on bal-
aging and sensory reintegration. Gait Pos- cause of falls in the elderly. Postgrad Med. ance control in the elderly. Med Sci Sports
ture. 2001;14:203–210. 1996;99:161–172. Exerc. 2004;36:648 – 657.
4 Quoniam C, Hay L, Roll JP, Harlay F. Age 17 Rose DJ. FallProof! A Comprehensive Bal- 30 Westlake KP, Wu Y, Culham EG. Sensory-
effects on reflex and postural responses to ance and Mobility Training Program. specific balance training in older adults:
propriomuscular inputs generated by ten- Windsor, Ontario, Canada: Human Kinet- effect on position, movement, and veloc-
don vibration. J Gerontol A Biol Sci Med ics; 2003. ity sense at the ankle. Phys Ther. 2007;87:
Sci. 1995;50:B155–B165. 560 –568.
18 Maki BE, Holliday PJ, Fernie GR. Aging and
5 Camicioli R, Panzer VP, Kaye J. Balance in postural control: a comparison of 31 Orrell AJ, Eves FF, Masters RS. Implicit mo-
the healthy elderly: posturography and spontaneous- and induced-sway balance tor learning of a balancing task. Gait Pos-
clinical assessment. Arch Neurol. 1997;54: tests. J Am Geriatr Soc. 1990;38:1–9. ture. 2006;23:9 –16.
976 –981. 19 Lafond D, Corriveau H, Hebert R, Prince F. 32 Huxhold O, Li SC, Schmiedek F, Linden-
6 Shumway-Cook A, Woollacott M. Atten- Intrasession reliability of center of pres- berger U. Dual-tasking postural control:
tional demands and postural control: the sure measures of postural steadiness in aging and the effects of cognitive demand
effect of sensory context. J Gerontol A healthy elderly people. Arch Phys Med Re- in conjunction with focus of attention.
Biol Sci Med Sci. 2000;55:M10 –M16. habil. 2004;85:896 –901. Brain Res Bull. 2006;69:294 –305.
7 Woollacott M, Shumway-Cook A. Atten- 20 Raymakers JA, Samson MM, Verhaar HJ. 33 Redfern MS, Jennings JR, Martin C, Furman
tion and the control of posture and gait: a The assessment of body sway and the JM. Attention influences sensory integra-
review of an emerging area of research. choice of the stability parameter(s). Gait tion for postural control in older adults.
Gait Posture. 2002;16:1–14. Posture. 2005;21:48 –58. Gait Posture. 2001;14:211–216.
8 Rankin JK, Woollacott MH, Shumway- 21 Uimonen S, Sorri M, Laitakari K, Jamsa T. A 34 Condron JE, Hill KD. Reliability and valid-
Cook A, Brown LA. Cognitive influence on comparison of three vibrators in static pos- ity of a dual-task force platform assessment
postural stability: a neuromuscular analy- turography: the effect of vibration ampli- of balance performance: effect of age, bal-
sis in young and older adults. J Gerontol A tude on body sway. Med Eng Phys. 1996; ance impairment, and cognitive task. J Am
Biol Sci Med Sci. 2000;55:M112–M119. 18:405– 409. Geriatr Soc. 2002;50:157–162.
9 Peterka RJ. Sensorimotor integration in hu- 22 Ribot-Ciscar E, Rossi-Durand C, Roll JP. 35 Stelmach GE, Teasdale N, Di Fabio RP,
man postural control. J Neurophysiol. Muscle spindle activity following muscle Phillips J. Age related decline in postural
2002;88:1097–1118. tendon vibration in man. Neurosci Lett. control mechanisms. Int J Aging Hum
1998;258:147–150. Dev. 1989;29:205–223.
10 Peterka RJ, Loughlin PJ. Dynamic regula-
tion of sensorimotor integration in human 23 Rose DJ, Lucchese N, Wiersma LD. Devel- 36 Tsang WW, Wong VS, Fu SN, Hui-Chan
postural control. J Neurophysiol. 2004;91: opment of a multidimensional balance CW. Tai Chi improves standing balance
410 – 423. scale for use with functionally indepen- control under reduced or conflicting sen-
dent older adults. Arch Phys Med Rehabil. sory conditions. Arch Phys Med Rehabil.
11 Xu D, Hong Y, Li J, Chan K. Effect of tai chi 2006;87:1478 –1485. 2004;85:129 –137.
exercise on proprioception of ankle and
knee joints in old people. Br J Sports Med. 24 Powell LE, Myers AM. The Activities- 37 Grindstaff TL, Christiano KE, Broos AM,
2004;38:50 –54. specific Balance Confidence (ABC) Scale. et al. Assessment of a practice effect in
J Gerontol A Biol Sci Med Sci. 1995;50A: serial sensory organization testing scores
12 Beard DJ, Dodd CA, Trundle HR, Simpson M28 –M34. of healthy adults. Percept Mot Skills. 2006;
AH. Proprioception enhancement for an- 102:379 –386.
terior cruciate ligament deficiency: a pro- 25 Myers AM, Powell LE, Maki BE, et al. Psy-
spective randomised trial of two physio- chological indicators of balance confi- 38 Bayouk JF, Boucher JP, Leroux A. Balance
therapy regimes. J Bone Joint Surg Br. dence: relationship to actual and per- training following stroke: effects of task-
1994;76:654 – 659. ceived abilities. J Gerontol A Biol Sci Med oriented exercises with and without al-
Sci. 1996;51:M37–M43. tered sensory input. Int J Rehabil Res.
13 Gauchard GC, Gangloff P, Jeandel C, 2006;29:51–59.
Perrin PP. Influence of regular propriocep- 26 Washburn RA, Smith KW, Jette AM, Janney
tive and bioenergetic physical activities on CA. The physical activity scale for the el- 39 Rucker D, Rowe BH, Johnson JA, et al. Ed-
balance control in elderly women. derly (PASE): development and evaluation. ucational intervention to reduce falls and
J Gerontol A Biol Sci Med Sci. 2003;58: J Clin Epidemiol. 1993;46:153–162. fear of falling in patients after fragility frac-
M846 –M850. ture: results of a controlled pilot study.
27 Washburn RA, McAuley E, Katula J, et al. Prev Med. 2006;42:316 –319.
14 Burke D, Hagbarth KE, Lofstedt L, Wallin The physical activity scale for the elderly
BG. The responses of human muscle spin- (PASE): evidence for validity. J Clin Epide- 40 Chang JT, Morton SC, Rubenstein LZ, et al.
dle endings to vibration of non- miol. 1999;52:643– 651. Interventions for the prevention of falls in
contracting muscles. J Physiol. 1976;261: older adults: systematic review and meta-
28 Hu MH, Woollacott MH. Multisensory
673– 693. analysis of randomised clinical trials. BMJ.
training of standing balance in older 2004;328:680.
15 Vuillerme N, Teasdale N, Nougier V. The adults, I: postural stability and one-leg
effect of expertise in gymnastics on pro- stance balance. J Gerontol. 1994;49:M52–
prioceptive sensory integration in human M61.
subjects. Neurosci Lett. 2001;311:73–76.


1274.full

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (20)

Similar to 1274.full

Similar to 1274.full (20)

Recently uploaded

Recently uploaded (20)

1274.full