Balance training following stroke: effects of task-oriented exercises ...

Original article 51
Balance training following stroke: effects of task-oriented
exercises with and without altered sensory input
Jean-François Bayouk a , Jean P. Boucher a and Alain Leroux b,c
The purpose of this study was to compare the effects of a
task-oriented exercise program with and without altered
sensory input on postural stability in subjects with stroke.
Sixteen hemiparetic subjects, at least 6 months
post-stroke, were randomly assigned to the experimental
or control group, and participated in an 8-week
task-oriented exercise program focusing on balance and
mobility exercises. Exercises were performed under
normal conditions by the control group, and under
conditions of vision and surface manipulation by the
experimental group. Pre- and post-test assessments
involved the measurement of the center of pressure
(COP) displacement during double-legged stance and
sit-to-stand under four sensory conditions: (1) eyes open,
normal surface; (2) eyes open, soft surface; (3) eyes
closed, normal surface; and (4) eyes closed, soft surface,
as well as the 10-m walking test. Results showed
significant improvements (P < 0.05) in COP displacement
under sensory conditions (1) and (2) for the experimental
group only, and limited changes for the sit-to-stand in both
groups after training. Significant improvements (P < 0.05)
were also found in both groups for the walking test. It is
concluded that a task-oriented exercise program, assisted
by sensory manipulation, is more effective at improving the
standing balance of stroke subjects than a conventional
task-oriented program.
Die vorliegende Studie vergleicht die Wirkung eines
anforderungsspezifischen Übungsprogramms mit und
ohne Sinnesreizänderung auf die posturale Stabilität von
Schlaganfallpatienten. Insgesamt 16 Hemiparetiker
wurden mindestens sechs Monate nach dem Schlaganfall
randomisiert der Versuchs- oder der Kontrollgruppe
zugeordnet, innerhalb derer sie acht Wochen an einem
anforderungsspezifischen Programm mit speziellen
Gleichgewichts- und Mobilitätsübungen teilnahmen. Die
Kontrollgruppe führte die Übungen unter normalen
Bedingungen durch, die Versuchsgruppe dagegen
unter Manipulation der Aspekte Sicht und Gehflächen. Bei
den Bewertungen vor und nach dem Test wurde die
Verlagerung des Druckmittelpunkts (COP) während der
zweibeinigen Haltung und der Aufstehübung anhand von
vier Sinneszuständen gemessen: (1) offene Augen,
normale Fläche, (2) offene Augen, weiche Fläche,
(3) geschlossene Augen, normale Fläche und (4)
geschlossene Augen, weiche Fläche sowie anhand des
10 m Gehtests. Die Ergebnisse wiesen nur bei der
Versuchsgruppe bei der COP-Verlagerung unter den
Sinneszuständen (1) und (2) beachtliche Verbesserungen
(P < 0,05) auf und bei beiden Gruppen in beschränktem
Maß Veränderungen bei der Aufstehübung. Bei beiden
Gruppen wurden auch signifikante Verbesserungen
(P < 0,05) beim Gehtest beobachtet. Daraus schließt sich,
dass ein anforderungsspezifisches Übungsprogramm mit
begleitender Sinnesmanipulation das Gleichgewicht von
Schlaganfallpatienten bei aufrechter Körperhaltung
effektiver verbessert als ein herkömmliches
anforderungsspezifisches Programm.
El propósito de este estudio fue comparar los efectos de
un programa de ejercicios dirigidos, con estimulación
sensorial alterada o sin ella, sobre la estabilidad postural
de sujetos con accidente vascular cerebral. Dieciséis
sujetos hemiparéticos que habían sufrido un accidente
vascular cerebral hacía al menos 6 meses, fueron
distribuidos al azar en dos grupos: uno experimental y uno
control. Los mismos participaron durante 8 semanas en un
programa de ejercicios dirigidos, el cual se centraba en
ejercicios de balance y de movilidad. El grupo control
realizó los ejercicios en condiciones normales, mientras
que el grupo experimental los realizó en condiciones en
que la visión y las superficies fueron alteradas. En las
evaluaciones realizadas antes y después de los ejercicios
se midió la desviación del centro de presión (CP) durante
la postura de pie utilizando ambas piernas, así como en la
postura sentada, listo para ponerse de pie, bajo cuatro
condiciones sensoriales deferentes: 1) ojos abiertos,
superficie normal; 2) ojos abiertos, superficie blanda; 3)
ojos cerrados, superficie normal; y 4) ojos cerrados,
superficie blanda. Se realizó además la prueba de la
marcha de los 10 m. Los resultados mostraron mejoras
significativas (P < 0,05) en la desviación del CP en ambos
grupos durante la prueba de la marcha. Se concluyó que
un programa de ejercicios dirigidos, en los que se utilicen
manipulaciones sensoriales, es más efectivo que un
programa convencional de ejercicios dirigidos para
mejorar el balance durante la postura de pie en sujetos con
accidente vascular cerebral.
Le but de cette étude était de comparer les effets d’un
programme d’exercices fonctionnels assistés ou non de
stimulations sensorielles sur la stabilité posturale de
sujets atteints d’un accident vasculaire cérébral (AVC).
Seize sujets hémiparétiques atteints d’un AVC depuis au
moins 6 mois et répartis de façon aléatoire au sein du
groupe expérimental et du groupe témoin ont participé à
un programme d’exercices fonctionnels de huit semaines
portant sur des exercices d’équilibre et de mobilité. Les
exercices étaient exécutés en situation normale par le
groupe témoin et en situation de manipulation de la vision
0342-5282 c 2006 Lippincott Williams & Wilkins
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52 International Journal of Rehabilitation Research 2006, Vol 29 No 1
et de la surface de support par le groupe expérimental. Les
évaluations pré et post exercices ont été effectuées à l’aide
de la mesure du déplacement du centre de pression (CP)
lors du maintien de la position debout en appui bipodal et
du transfert assis-debout selon les quatre conditions
sensorielles suivantes: yeux ouverts, surface normale (1);
yeux ouverts, surface moelleuse (2); yeux fermés, surface
normale (3); yeux fermés, surface moelleuse (4). Le test de
marchede10mètres a aussi été inclus dans l’évaluation.
Les résultats ont démontré une amélioration significative
(P < 0.05) du déplacement du CP dans les conditions 1 et 2
pour le groupe expérimental seulement ainsi que des
changements limités pour le transfert assis-debout chez
les deux groupes de sujets à la suite de l’entraînement.
Une amélioration significative (P < 0.05) a été observée au
niveau du test de marche chez les deux groupes de sujets.
Cette étude a démontré qu’un programme d’exercices
fonctionnels assistés de stimulations sensorielles est plus
efficace pour l’amélioration du maintien de l’équilibre en
position debout chez les sujets atteints d’un AVC qu’un
programme d’exercices fonctionnels conventionnnel.
International Journal of Rehabilitation Research 29:51–59
c 2006 Lippincott Williams & Wilkins.
International Journal of Rehabilitation Research 2006, 29:51–59
Keywords: exercise, stroke, multisensory training, hemiparesis, hemiplegia,
balance, postural stability
a Department of Kinanthropology, University of Quebec in Montréal, Montréal,
Canada, b Department of Exercise Science, Concordia University, Montréal,
Canada and c Centre de Recherche Interdisciplinaire en Réadaptation du
Montréal Métropolitan-Site, Constance-Lethbridge Rehabilitation Centre,
Montreal, Canada.
Correspondence and requests for reprints to Alain Leroux, Department of
Exercise Science, Concordia University, 7141 Sherbrooke West, Montréal
(Quebec), Canada H4B 1R6.
Tel: + 1 514 84803326; fax: + 1 514 848 8681;
e-mail: alerou@alcor.concordia.ca
Sponsorship: Funding for this study was provided by the Faculty of Arts and
Science of Concordia University (no. NS2001-001).
Received 2 May 2005 Accepted 11 July 2005
Introduction
Balance impairment is important to consider after stroke
since the number of falls can be as high as five per year in
the first year post-lesion (Nyberg and Gustafson, 1995).
These falls can further lead to pathological events (e.g.
hip fractures), and additional declines in function and
disability status (Grisso et al., 1991). The decreased
ability to maintain static and dynamic balance after stroke
could be related to the inability to select reliable sensory
information (visual, vestibular and somatosensory systems)
in order to produce the proper motor action
necessary to maintain postural stability (Shumway-Cook
et al., 1988; Di Fabio and Badke, 1991; Bonan et al., 2004a).
It was found, for instance, that stroke subjects having
impaired ankle proprioception exhibited a significant
increase in postural sway as compared to stroke subjects
showing intact proprioception during double-legged
stance (Niam et al., 1999). Furthermore, when sensory
inputs from the visual, vestibular and somatosensory
systems were manipulated, stroke subjects exhibited
greater postural instability than healthy subjects (Di
Fabio and Badke, 1991; Bonan et al., 2004a).
Exercise interventions, in the form of task-oriented
exercise programs, are now recognized as a new strategy
to improve the functional status of chronic stroke
individuals (Dean et al., 2000; Eng et al., 2003; Salbach
et al., 2004; Leroux, 2005) Hence, following several weeks
of functional training, hemiparetic subjects, secondary to
stroke, have shown significant improvements in functional
mobility (Eng et al., 2003; Leroux, 2005), walking
speed and endurance (Dean et al., 2000; Eng et al., 2003;
Salbach et al., 2004), and in clinical measures of balance
(Dean et al., 2000; Eng et al., 2003; Leroux, 2005). When
using laboratory measures of static and dynamic balance,
task-oriented exercises did not, on the other hand, have
any effect over the abnormally increased lateral sway
exhibited by stroke subjects during double-legged stance
and sit-to-stance tasks (Leroux, 2002). Since stroke
subjects often present with somatosensory deficits
(Smith et al., 1983; Di Fabio and Badke, 1990; Carr and
Shepherd, 1998), the adaptation of regular exercises with
the use of surface and vision manipulation to challenge
balance could improve the process of somatosensory
integration and have a positive effect on postural stability.
This type of intervention has further shown to be
effective at improving postural stability in neurologically
intact elderly people (Hu and Woollacott, 1994a,b).
Therefore, the main objective of this study was to
compare the effects of a task-oriented exercise program
with and without altered sensory input on postural
stability in two groups of hemiparetic subjects secondary
to stroke. A second objective was to establish the
feasibility of multisensory training in older adults with
stroke.
Methods
Subjects
Sixteen hemiparetic subjects, secondary to stroke, were
recruited from physiotherapy clinics, hospital centers and
local stroke community groups (see Table 1). To be
eligible to participate in the study, all subjects had to
fulfill the following criteria: (1) be victim of a stroke
that resulted in hemiparesis, (2) be at least 6 months
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Balance training following stroke Bayouk et al. 53
Table 1
Profile of the stroke subjects (mean ± SD)
Control group (n = 8) Experimental group (n =8)
Age (years) 62.0 ± 4.6 68.4 ± 7.1
Time since stroke (years) 5.7 ± 6.9 7.1 ± 12.5
Chedoke–McMaster stroke assessment score (/7) 4.6 ± 1.1 4.9 ± 1.25
Gender (n)
Male 3 6
Female 5 2
Hemiparetic side (n)
Right 4 2
Left 4 6
post-stroke, (3) be fully discharged from all rehabilitation
program and (4) obtain written approval from a
primary care physician. Exclusion criteria were: a severe
limitation that would limit the subject’s participation
in the exercise program or interfere with functional
assessments performed in this study. Prior to beginning
the study, every subject signed an informed consent
document. Ethical approval was obtained from the ethics
committees of the Cummings Jewish Centre for Seniors
(CJCS) and Concordia University (Montréal, Québec,
Canada).
Research design
Stroke subjects were matched in pairs of two according to
the Chedoke–McMaster Stroke Assessment stage of their
mobility affected leg (Gowland et al., 1995) and randomly
assigned to the experimental or control group. Each group
was tested before and immediately after the end of the
8-week exercise program.
Exercise program
Subjects from both groups participated in a 1-h (twice a
week) exercise class for a period of 8 weeks. The exercise
classes were held at the Wellness Centre of the CJCS
(Montréal, Québec, Canada) and supervised by the same
clinical exercise physiologist assisted by two intern
students. Details on the Wellness Centre exercise
program of the CJCS have been reported in a previous
paper (Leroux, 2005). The main objective of this program
is to strengthen the hemiparetic side of stroke subjects by
the practice of functional exercises (Leroux, 2005).
Secondary objectives include the improvement of balance,
gait and coordination. In the present study,
experimental and control group subjects participated in
exercise sessions composed of the following task-oriented
exercises: (1) stepping forward, backward, and sideways
on the exercise step; (2) stepping over blocks of various
heights; (3) standing up from a chair, walking four steps
forward, performing a bilateral stool touch and walking
backwards to the chair; (4) standing up from a chair,
walking four steps forward, turning to the right, stepping
over the exercise step, turning to the right again and
walking forwards to the chair (repeat the exercise circuit
in opposite direction); (5) from a sitting position on a
65-cm Swiss ball, performing a range of motion and
balance exercises (forward and backward rolling of the
arms; bending the trunk forward and side to side); (6)
performing double-legged stance for 10 s; (7) performing
tandem stance for 10 s; (8) rising from a chair without the
use of the arms; (9) walking forward and backward with a
tandem walking pattern (toes of one foot touching the
heel of the foot in front); and (10) performing singlelegged
stance for 10 s.
Control group subjects performed all of the above
exercises under normal conditions (i.e. with eyes open
and on a hard regular surface). The level of difficulty of
the exercises was adjusted according to the progression of
each subject. The number of repetitions, the height of
the exercise step and the ankle weight were modified
progressively. Experimental group subjects performed
exercises one to five under normal conditions in the first
20 min of each session. The second part of the session
(30 min) aimed at improving static and dynamic balance
by executing exercises while the proprioception of the
feet and ankles and/or vision was manipulated. As part of
this multisensory training, experimental subjects performed
exercises (6) to (10) under the following
conditions: (1) eyes open, firm surface; (2) eyes open,
soft surface; (3) eyes closed, firm surface; and (4) eyes
closed, soft surface. The soft surface condition was
performed with subjects standing on a 50 cm 62 cm
foam mat (CFC free foam, 2.5 cm thick). To progress
from one sensory condition to the next, the participants
had to perform the exercise without any assistance and
with proper form. Finally, both groups of subjects
completed their session with a 10-min cool-down period
where flexibility and range of motion exercises were
performed in a seated position. These exercises focused
on the major muscles groups involved during the class
(quadriceps, hamstrings, hips, lower and upper back, and
neck).
Evaluation
Subjects were evaluated before (pre-test) and after (posttest)
the 8-week exercise program. Subjects’ postural
sway was measured during the following tasks: (1)
double-legged stance for 10 s and (2) sit-to-stand from a
chair. For the double-legged stance, subjects were
instructed to maintain a steady posture and a horizontal
gaze without moving the head. During the sit-to-stand
test, subjects were seated on an armless chair adjusted to
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54 International Journal of Rehabilitation Research 2006, Vol 29 No 1
their lower-leg length and were instructed to stand up at
their self-paced comfortable speed without using their
arms (Engardt et al., 1995; Cheng et al., 1998, 2001; Eng
and Chu, 2002). The two tasks were performed under the
following sensory conditions: (1) eyes open, firm surface;
(2) eyes open, soft surface; (3) eyes closed, firm surface;
and (4) eyes closed, soft surface. This order was followed
for each task and each subject. For each sensory
condition, subjects completed three trials of the double-legged
stance task and three trials of the sit-to-stand
task. In the event of unsuccessful trials, subjects were
allowed an additional trial to complete the task. In
addition to balance tasks, subjects’ functional performance
was assessed using the 10-m walking test. Subjects
were instructed to walk as fast as possible with the use of
their regular assistive device. Walking speed was measured
by timing subjects over the 10-m distance.
To decrease the effects of acceleration and deceleration,
measurements were taken over the middle 10-m of a
20-m distance. A stopwatch was used to calculate the
time of each subject and the test was performed once.
The displacement of the center of pressure (COP)
during double-legged stance and sit-to-stance tasks was
measured with the Matscan system (Tekscan, Boston,
Massachusetts, USA). The Matscan is a pressure sensing
floor mat (43.2 cm 36.8 cm) consisting of 2288 sensors
to measure the applied pressures at a sampling rate
of 40 Hz. This technology has been used successfully
in several clinical trials (Henderson et al., 1994; Randolph
et al., 2000; Caseli et al., 2002; Smith et al., 2002;
Ducic et al., 2004), and has been shown to be accurate
(Hsiao et al., 2002) and reliable (Ahroni et al., 1998;
Randolph et al., 2000; Pinet et al., 2003).
Quantification and analysis
The measures of COP variability and total excursion were
used to evaluate static and dynamic balance. The
standard deviation of the COP displacement was
calculated to determine the variability in anteroposterior
(A/P) and mediolateral (M/L) axes during double-legged
stance (Goldie et al., 1989; Winstein et al., 1989; Goldie
et al., 1992; Karlsson and Frykberg, 2000; Palmieri et al.,
2002). For the sit-to-stand task, postural stability was
measured using the peak-to-peak amplitude of the COP
displacements in A/P and M/L axes, and reported as COP
total excursion (Cheng et al., 1998, 2001; Leroux, 2002).
Descriptive statistics were performed on the nine test
conditions per subject (mean and standard deviation).
Statistical analyses for all the variables were done in
SigmaStat (SPSS Inc., version 2.03) using a two-way
ANOVA with repeated measures. When significant
differences were found (P < 0.05), pair wise comparisons
were made using the Tukey test.
Results
Exercise program participation
Experimental and control group subjects showed a very
high participation rate in the 8-week exercise program.
Among the eight subjects forming the experimental
group, six of them completed all exercise sessions and
the two other subjects missed one session each. For the
control group, six subjects took part in all exercise
sessions, one subject missed one session and another
subject missed two sessions. Subjects from both groups
completed the missing sessions immediately after the
end of the 8-week program.
Compliance to the multisensory exercise program
Table 2 illustrates the level of achievement of the
experimental group during the multisensory program. It
can be seen that the double-legged stance was the only
task that was successfully completed by all subjects under
the four sensory conditions. When performing more
challenging balance tasks, such as tandem stance and
rising from a chair, seven subjects out of eight completed
the control (eyes open, firm surface) and the surface
manipulation conditions, whereas six of them achieved the
vision manipulation condition under firm and soft surfaces.
The task of walking forward and backward with a tandem
foot pattern was also successfully completed by most
subjects (six out of eight subjects) for conditions (1) and
(2) only. When asked to repeat the task under conditions
(3) and (4), however, none of the subjects achieved it.
Finally, only two subjects were able to complete the singlelegged
stance for 10 s and under condition (1) only.
Table 2 Number of experimental group subjects (out of 8) who successfully completed the task-oriented exercises under each sensory
condition
Task-oriented exercises
Sensory conditions (n)
Eyes open, hard surface Eyes open, soft surface Eyes closed, hard surface Eyes closed, soft surface
Double-legged stance for 10 s 8 8 8 8
Tandem stance during 10 s 7 7 6 6
Rising from a chair without using
7 7 6 6
the arms
Forward and backward walking
6 6 0 0
with a tandem walking pattern
Single-legged stance for 10 s 2 0 0 0
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Balance training following stroke Bayouk et al. 55
Changes in postural stability
Figure 1 shows the changes in COP variability between
pre- and post-test measures for double-legged stance
performed under the four sensory conditions by experimental
and control groups. Significant group test interactions
were observed for conditions one and two (Fig. 1a
and b). Post hoc tests showed that, unlike controls,
experimental group subjects significantly reduced
(P < 0.05) their COP variability in M/L and A/P axes
for the eyes open, firm surface and the eyes open, soft
surface conditions, respectively (Fig. 1a and b). A trend of
improvement in M/L COP variability of experimental
group subjects was also observed for the eyes open, soft
surface (condition 2) and the eyes closed, firm surface
conditions (condition 3). Although not statistically
significant (P < 0.15), the decrease of COP variability
was found in six subjects out of eight for the latter
sensory conditions.
Fig. 1
(a) Eyes open, firm surface
A/P axis
4
COP variability (cm)
0
Exp. group Control group
Pre-test
Post-test
2
0
∗
Exp. group
M/L axis
Control group
(b) Eyes open, soft surface
A/P axis
4
COP variability (cm)
∗
0
Exp. group Control group
2
0
Exp. group
M/L axis
Control group
(c) Eyes closed, firm surface
A/P axis
4
COP variability (cm)
0
Exp. group Control group
2
0
M/L axis
Exp. group
Control group
(d) Eyes closed, soft surface
A/P axis
4
COP variability (cm)
0
Exp. group Control group
2
0
M/L axis
Exp. group
Control group
COP variability between pre- and post-test measures during double-legged stance performed under four sensory conditions by experimental and
control groups. Results for the A/P axis are shown on the left graphs and those for the M/L axis appear on the right. Note that the ordinal scales are
the same across all sensory conditions. * Significant difference between pre- and post-test measures.
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

56 International Journal of Rehabilitation Research 2006, Vol 29 No 1
The changes in COP total excursion between pre- and posttest
measures for sit-to-stand performed under the four
sensory conditions by experimental and control groups are
illustrated in Figure 2. Results revealed a main effect due to
tests for the COP total excursion in A/P axis. Post hoc tests
showed that both groups significantly reduced (P < 0.05)
their COP total excursion in A/P axis for the eyes open, soft
surface condition (condition 2; Fig. 2b). No significant main
effects or group test interaction effects were found under
the other sensory conditions for the sit-to-stand task.
Ten-meter walking test
The pre–post-test scores for the 10-m walking test
revealed a main effect due to tests indicating that both
groups significantly decreased (P < 0.05) the time
needed to complete the walking test after the exercise
program. The experimental group showed a change from
20.8 ( ± 8.3) to 18.3 ( ± 6.5)s while the control group
evidenced a change from 22.4 ( ± 13.8) to 19.7 ( ± 12.3)s
following exercise intervention. The percentage improvement
was in the order of 12.2% for the experimental
Fig. 2
(a) Eyes open, firm surface
A/P axis
15
COP excursion (cm)
0
Exp. group Control group
Pre-test
Post-test
22
0
Exp. group
M/L axis
Control group
(b) Eyes open, soft surface
∗
A/P axis
15
COP excursion (cm)
0
Exp. group Control group
∗
22
0
M/L axis
Exp. group
Control group
(c) Eyes closed, firm surface
A/P axis
15
COP excursion (cm)
0
Exp. group Control group
22
0
M/L axis
Exp. group
Control group
(d) Eyes closed, soft surface
A/P axis
15
COP excursion (cm)
0
Exp. group Control group
22
0
M/L axis
Exp. group
Control group
COP total excursion between pre- and post-test measures during sit-to-stand performed under four sensory conditions by experimental and control
groups. Results for the A/P axis are shown on the left graphs and those for the M/L axis appear on the right. Note that the ordinal scales are the same
across all sensory conditions. * Significant difference between pre- and post-test measures.
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

Balance training following stroke Bayouk et al. 57
group and 12.0% for the control group. No significant
main effects or group test interaction effects were found
for this test.
Discussion
The results from this study indicated that a task-oriented
exercise program with altered sensory input was feasible
and could significantly improve standing balance in
hemiparetic subjects secondary to stroke. This effect
was not found in hemiparetic subjects exercising without
altered sensory input. Furthermore, the postural stability
of stroke subjects during sit-to-stand was minimally
affected by both types of training, but the walking speed
of experimental and control group subjects significantly
improved after exercise intervention.
Effects of task-oriented exercises on balance
Our results showed that the addition of a multisensory
training component to the regular exercise program was
required to obtain a significant improvement in standing
balance of stroke subjects. In the absence of sensory
training, very limited changes were observed for both
static and dynamic balance tasks. These results are in
agreement with our previous study showing limited
effects of task-oriented exercises without sensory training
on postural sway of stroke subjects during double-legged
stance and sit-to-stance tasks (Leroux, 2002). Even
though stroke subjects could significantly improve their
scores on functional measures of balance and mobility
after such training (Dean et al., 2000; Eng et al., 2003;
Leroux, 2005), these improvements did not translate into
a reduction of the abnormally increased lateral sway
exhibited by stroke subjects during double-legged stance
and sit-to-stance tasks (Leroux, 2002). This lack of effect
tends to show that balance senses have to be specifically
targeted when designing balance-retraining programs for
hemiparetic subjects.
Balance improvement after multisensory training
Balance impairments following stroke have been associated
with deficits in sensorimotor integration (Di Fabio
and Badke, 1991) and an inability to select the pertinent
sensory input (Bonan et al., 2004a,b). For instance, under
conditions of sensory deprivation, it has been shown that
stroke subjects presented with greater postural instability
than healthy subjects of similar ages (Di Fabio and Badke,
1991; Bonan et al., 2004a). In our study, the significant
decrease in the M/L sway during standing for the control
condition (eyes open, firm surface) after sensory training
was likely to be the result of the increased use of
somatosensory, visual and vestibular information when
performing the various exercises under sensory deprivation
conditions. This sensory compensation might have
improved sensorimotor integration of postural control in
the central nervous system, serving to activate and
coordinate motor processes (e.g. action of the proper
muscles synergies) (Hu and Woollacott, 1994a,b; Bonan
et al., 2004b). Using a static standing balance protocol
involving sensory manipulation of the visual, vestibular
and somatosensory systems, Hu and Woollacott (1994a)
reported important changes in muscle and movement
characteristics of postural responses after 10 h of training
in healthy older adults. The changes were characterized
by a reduction in the latency of muscle activation and
kinematic patterns, and by a decrease of the response
frequency of antagonist muscles in reaction to platform
translation perturbations. Bonan et al. (2004b) also
reported that balance improved more after rehabilitation
with visual deprivation than with free vision in stroke
subjects. These results suggest that enhanced multisensory
interaction resulting from sensory training could
have improved the sensorimotor integration of postural
stability of hemiparetic subjects secondary to stroke.
Our findings showed that standing balance was improved
under conditions of sensory deprivation after the multisensory
training. A significant decrease in A/P sway was
found under the eyes open, soft surface condition, and a
trend of improvement in M/L sway was observed for the
eyes open, soft surface and the eyes closed, firm surface
conditions. The lack of significance was probably due to
the small sample size since six subjects out of eight
showed a decrease in M/L sway for the latter sensory
conditions. One possible mechanism for this improvement
is that stroke subjects were able to select reliable
sensory information for postural control more efficiently
following the multisensory training (Hu and Woollacott,
1994a,b; Bonan et al., 2004b). Bonan et al. (2004a)
suggested that postural imbalance might be due more
to a higher-level inability to select reliable sensory input
than to elementary sensory impairment. When the
subjects were standing on the soft surface, their balance
was challenged due to the unstable surface and the lack
of accurate somatosensory information. In this condition,
the pertinent sensory inputs for postural stability might
come from the vestibular and visual systems. Our results
suggest that these compensatory mechanisms can occur
and be improved with proper sensory training after a
cerebrovascular accident.
As opposed to standing, changes in postural sways during
sit-to-stand were very limited after exercising with and
without sensory training. This lack of effect may be
explained by several factors. Performing a sit-to-stand
movement requires a great amount of coordination and
muscular strength from all regions of the body (Engardt
and Olsson, 1992; Millington et al., 1992; Vander Linden
et al., 1994; Engardt et al., 1995; Kerr et al., 1997). These
characteristics are highly stressed when performing
repetitive sit-to-stand movements, and are likely to
respond quickly and favorably to short-term training.
Previous studies have shown that following 4–8 weeks of
task-oriented exercises, stroke subjects could perform
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58 International Journal of Rehabilitation Research 2006, Vol 29 No 1
this movement faster and with better weight-bearing
symmetry from lower limbs (Dean et al., 2000; Leroux,
2002). However, these changes were not accompanied by
a reduction in the abnormally elevated M/L sway
(Leroux, 2002). In the present study, the fact that the
postural sway of experimental group subjects was in a
normal range for sway at pre-test when compared with
age- and sex-matched healthy subjects (Leroux, 2002)
might have also influenced the possible improvement
that can be induced by multisensory training or other
type of training programs. As for other types of training
regiments, we believe that the training volume is the
most important factor to consider. Because of the
restricted allotted time devoted to the sensory training
and the fatigue component when performing sit-to-stand
movements, the participants spent more time practicing
double-legged stance than sit-to-stand. On the other
hand, Cheng et al. (2001) showed that the postural sway
of stroke individuals could be improved following
repetitive sit-to-stand training through use of a standing
biofeedback trainer but this required a more intense
program (5 times/week).
Improvement in functional performance
The 10-m walking test was included to obtain an
estimate of the changes in the functional performance
of stroke subjects after exercise intervention. The
improvements obtained in this test could have a positive
impact for maintaining physical independence in stroke
subjects. When converted into walking speed, experimental
group subjects showed a change from 0.48 to
0.55 m/s and control group subjects from 0.45 to 0.51 m/s
when performing the 10-m walking test after exercise
training. These changes are probably significant from a
clinical point of view, Perry et al. (1995) having
demonstrated that a walking speed of 0.4 ± 0.18 m/s or
less restricts a stroke individual’s capacity for community
ambulation.
Our findings showed that the addition of a sensory
component to the task-oriented exercise program did not
lead to greater improvement in walking speed of
hemiparetic subjects. The transference of balance training
to walking function has not been clearly established
and remains a controversial issue in the literature
(Nichols, 1997). It is interesting to note that despite
the fact that experimental group subjects devoted more
time practicing static tasks like double-legged standing,
they improved their walking speed to the same extent as
control group subjects. We believe that this increased
walking speed was likely to be the result of practicing
tasks involving a mobility component.
Conclusion
Our results showed that a task-oriented exercise program
assisted by sensory manipulation was feasible and more
effective for the improvement of the standing balance of
hemiparetic subjects secondary to stroke than a conventional
task-oriented program. The significant improvements
in mediolateral sway when performing a standing
stance with eyes open on a firm surface further suggest an
improvement in the sensorimotor integration following
the multisensory program.
Acknowledgements
The authors wish to thank Maria Fragapane (Cummings
Jewish Centre for Seniors) for the conceptualization and
supervision of the exercise program, and for her assistance
in the development of the multisensory component of
the program. Funding for this study was provided by the
Faculty of Arts and Science of Concordia University (no.
NS2001-001).
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