Monjezi_Effects of dual-task balance training on postural performance in patients with Multiple Sclerosis

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Clinical Rehabilitation
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DOI: 10.1177/0269215516639735
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CLINICAL
REHABILITATION
Effects of dual-task balance 
training on postural performance 
in patients with Multiple Sclerosis: 
A double-blind, randomized 
controlled pilot trial
Saeideh Monjezi1, Hossein Negahban2, Shirin Tajali3, 
Nava Yadollahpour3 and Nastaran Majdinasab4
Abstract
Objective: To investigate the effects of dual-task balance training on postural performance in patients 
with multiple sclerosis as compared with single-task balance training.
Design: Double-blind, pretest-posttest, randomized controlled pilot trial.
Setting: Local Multiple Sclerosis Society.
Subjects: A total of 47 patients were randomly assigned to two equal groups labeled as single-task 
training and dual-task training groups.
Interventions: All patients received supervised balance training sessions, 3 times per week for 4 weeks. 
The patients in the single-task group performed balance activities, alone. However, patients in dual-task 
group practiced balance activities while simultaneously performing cognitive tasks.
Main measures: The 10-Meter Walk Test and Timed Up-and-Go under single-task and dual-task 
conditions, in addition to Activities-specific Balance Confidence, Berg Balance Scale, and Functional 
Gait Assessment were assessed pre-, and post intervention and also 6-weeks after the end of 
intervention.
Results: Only 38 patients completed the treatment plan. There was no difference in the amount of 
improvement seen between the two study groups. In both groups there was a significant effect of time for 
dual-10 Meter Walk Test (F1, 36=11.33, p=0.002) and dual-Timed Up-and-Go (F1, 36=14.27, p=0.001) but 
not for their single-tasks. Moreover, there was a significant effect of time for Activities-specific Balance 
Confidence, Berg Balance Scale, and Functional Gait Assessment (P<0.01).
1 Musculoskeletal Rehabilitation Research Center, Ahvaz 
Jundishapur University of Medical Sciences, Ahvaz, Iran
2 Department of Physical Therapy, School of Paramedical 
Sciences, Mashhad University of Medical Sciences, Mashhad, 
Iran
3 Musculoskeletal Rehabilitation Research Center, Ahvaz 
Jundishapur University of Medical Sciences, Ahvaz, Iran
639735 CRE0010.1177/0269215516639735Clinical RehabilitationMonjezi et al.
research-article2016
Original Article
4 Neurologist, Department of Neurology, Musculoskeletal 
Rehabilitation Research Center, Ahvaz Jundishapur University 
of Medical Sciences, Ahvaz, Iran
Corresponding author:
Hossein Negahban, Department of Physical Therapy, School 
of Paramedical Sciences, Mashhad University of Medical 
Sciences, Mashhad, Iran. 
Email: honegahban@yahoo.com
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2 Clinical Rehabilitation 
Introduction
Patients with Multiple Sclerosis (MS) exhibit 
postural instability as well as cognitive impair-
ments even at the earliest stage of the disease.1–3 
Although there are some evidences that postural 
instability in patients with MS can be minimized 
with single-task balance exercises,4–6 there have 
been limited evidences related to the effects of 
dual-task balance exercises in this specific patient 
population. Dual-task activities that involve both 
motor and cognitive resources (e.g. thinking while 
standing and talking while walking) constitute a 
significant portion of most activities of daily liv-
ings.3 Patients with MS may have difficulty in 
concurrent execution of these activities. Given the 
apparent cognitive deficits (such as impaired 
information processing speed) in patients with 
MS,3 some evidences support the notion of decre-
ment in balance performance when combined 
with simultaneous execution of a cognitive 
task.1,2,7 This cognitive-motor interference has 
been documented in dual-task studies in which 
postural control and gait of patients have been 
negatively affected by the addition of concurrent 
cognitive tasks.1,3,8,9
Some evidences have shown the positive effects 
of single-task balance exercises on patients with 
MS.4–6 However, no study has yet comprehensively 
evaluated the effects of dual-task balance-specific 
exercises and compared it with traditional single-task 
exercises in this specific patient population. To our 
knowledge, only one study has recently investigated 
the effectiveness of a video-game balance program 
by means of dual-task paradigm (i.e. exergaming 
with additional postural demands) in patients with 
MS.10 While the results were promising, this technol-
ogy may not be available in all clinical settings and 
also may not be sufficiently adaptive for patients 
with moderate to severe disability.11
Therefore, the aim of this randomized con-
trolled pilot study was to investigate the effects of 
dual-task balance training on postural performance 
of patients with MS as compared with single-task 
balance training. We hypothesized that dual-task 
balance training would improve the postural per-
formances and also, it would be more effective 
than single-task balance training.
Materials and methods
Patients
The registration number in the Iranian Register for 
Clinical Trials is IRCT2014051917752N1. The 
method of this study was approved by the local 
Ethics Committee (ETH number: 1392.302). All 
patients were given the informed consent form and 
offered the opportunity to ask any questions regard-
ing the study procedures. Following signed informed 
consent form, they completed the demographic vari-
ables of interest including age, gender, height, 
weight, time since disease, and years of education.
Patients’ disability level and cognitive impair-
ments were evaluated by the Expanded Disability 
Status Scale12 and Mini-Mental State Examination,9 
respectively. The inclusion criteria were (1) a neu-
rologist-confirm diagnosis of MS, relapsing-
remitting type, (2) an Expanded Disability Status 
Scale score of 2-5.5,13 since in our pilot study, 
patients with severe disability failed to perform/
complete the gait-related tests, (3) ability to stand 
without any support,1 and (4) ability to walk 100m 
independently. Patients were excluded if they had 
Conclusions: This pilot study did not show more benefits from undertaking dual-task training than 
single-task training. A power analysis showed 71 patients per group would be needed to determine 
whether there was a clinically relevant difference for dual-task gait speed between the groups.
Keywords
Dual-task, balance, training, multiple sclerosis, outcome
Received: 18 August 2015; accepted: 25 February 2016
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Monjezi et al. 3
(1) Mini-Mental State Examination less than 24 as 
they potentially have problem with understanding 
instructions during dual-task activities, (2) any 
neuro-musculo-skeletal disorders except MS lim-
iting gait and balance, (3) uncorrected visual dis-
orders, and (4) ongoing exacerbation of the 
symptoms.6
The method of randomization was a balanced 
randomization process in which patients were 
matched based on age and sex and randomly 
assigned to either the single-task training group or 
the dual-task balance training group in equal sam-
ple proportions using a table of random numbers.
Study interventions
This study was a double-blind, pretest-posttest, 
randomized controlled pilot trial in which neither 
the examiner nor the patients were aware of group 
assignment.
All patients received 45-minute, supervised bal-
ance training sessions, 3 times per week for 4 weeks, 
with a total of 12 training sessions. The balance-
specific exercise program was based on the exer-
cises provided in O’Sullivan and Schmitz14 
Plummer-D’Amato et al.,15 and Silsupadol et al.,16 
studies and has been described in details in Appendix 
1 (Supplementary material). In brief, the exerciseprotocol was included exercise in double/single leg 
standing and tandem standing on a variety of differ-
ent support surfaces (i.e. rigid and foam surfaces) 
with various sensory inputs (i.e. eyes open and 
closed). Also, walking activities including forward/
backward/side walking, walking on firm/foam sur-
faces, walking through obstacles and walking up 
and down stairs were exercised by each patient.
The patients in the single-task training group 
performed balance activities, alone. However, 
patients in dual-task training group practiced bal-
ance activities while simultaneously performing 
cognitive task including naming objects, remem-
bering things, and backward recitation of days, 
months, etc. Briefly, during the first training ses-
sions, we asked patients to practice balance activi-
ties while simultaneously perform an easy cognitive 
task (such as name words in category, backward 
recitation of days of week, and remembering 4-item 
grocery list or 4 numbers). In the final sessions, 
patients performed balance activities combined 
with a hard cognitive task (such as name words 
starting with a single letter, backward recitation of a 
group of alphabet, and remembering phone num-
bers) (see Appendix 2, Supplementary material for 
details). Patients in both groups were advised to 
continue their usual medical care throughout the 
study.
Outcome measurements
The primary outcome measures were 10 Meter 
Walk test17 and Timed Up and Go test6 under sin-
gle-task and dual-task conditions. The secondary 
outcome measures were Activities-specific Balance 
Confidence,7 Berg Balance Scale,4 and Functional 
Gait Assessment.18 Also, the cognitive scores of 
dual-10 Meter Walk test and dual-Timed Up and 
Go test were considered as secondary outcome 
measures. The order of all these measures was ran-
domized between patients to control learning and 
fatigue effects. All outcome measures were col-
lected at baseline (pretest), at the end of training 
session (posttest) and also at 6-weeks after the end 
of training sessions to test retention (follow-up). 
These measurements were performed by an exam-
iner (ST) who was blinded to the group allocation. 
Before the baseline assessment, all patients were 
familiarized with the various test conditions and 
practiced them correctly.
The 10 Meter Walk test was performed alone 
with no additional task (i.e. single-10 Meter Walk 
test) and also with a concurrent cognitive challenge 
(i.e. dual-10 Meter Walk test). During single test, 
patients walked 10m at their usual comfortable 
speed and the time to complete the middle 6m was 
recorded by a stopwatch.17 In dual-10 Meter Walk 
test patients were asked to walk 10m and at the 
same time count backward by three from a random 
number between 100 and 200. The cognitive score 
was based on the final number reported by patient 
and the number of subtractions. If the final number 
is accurate, one score would be added to the num-
ber of subtracting items and if the final number is 
not accurate, only the number of subtracting items 
would be considered as cognitive score.
The Timed Up and Go was performed both alone 
and with a concurrent cognitive task of backward 
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4 Clinical Rehabilitation 
counting by three from a random number between 
20 and 100.6,8 In this test, the total time require to 
rise from an armchair, walk 3m, turn around, walk 
back, and sit down again on a chair was recorded by 
a stopwatch.8,19 The test-retest reliability and valid-
ity of Timed Up and Go was satisfactory for patients 
with MS.6,18
The Activities-specific Balance Confidence is a 
self-reported instrument of balance confidence 
during 16 different daily activities. A confidence 
rating scale ranges from 0% (not at all confident) to 
100% (full confident).2,7 The reliability and valid-
ity of this instrument has been established in 
patients with MS.7,20
The Berg Balance Scale consists of perfor-
mance of 14 different activities common in every-
day life and the patient’s score is rated by a 
clinician on a 0 (cannot perform) to 4 (normal per-
formance) scale with a total scoring range of 0 to 
56. The Berg Balance Scale is a reliable and valid 
instrument to examine functional balance in 
patients with MS.4,18,21
The Functional Gait Assessment consists of 10 
items covering walking in different conditions. 
This scale ranges from 0 to 30, with lower scores 
indicating greater walking impairment.18 The 
Functional Gait Assessment is a valid measure of 
dynamic balance in patients with MS.
Statistical analysis
Data were analyzed using SPSS software (SPSS 
Inc., Chicago, IL, USA) version 18.0 for windows. 
The normality of the data distribution was assessed 
by the Shapiro-Wilk test.
The balance training effects on all outcome 
measures were evaluated using 2-way mixed-
effects repeated measures analysis of variance 
with group (2 levels: single-task training and dual-
task training) as the between-subjects variable and 
time (2 levels: pretest and posttest) as within-sub-
jects variable. For patients who completed the 
follow-up testing (n= 14 in single-task training 
group and n=16 in dual-task training group), a 
repeated measure analysis of variance was con-
ducted to examine changes between pretest, post-
test, and follow-up data.
Results
This study consisted of 47 ambulatory patients 
with MS recruited from the local Multiple Sclerosis 
Society at the School of Rehabilitation Sciences, 
AJUMS. During the 4-weeks intervention, nine 
patients in both groups dropped out of the protocol 
due to their work schedules (n=5), knee pain, back 
pain and ankle sprain (n=2 in the single-task and 
n=2 in the dual-task group) (Figure 1). Patients 
consisted of 15 females and 4 males in both experi-
mental groups. From 38 patients (80.85%) who 
completed the treatment plan and underwent the 
posttest evaluation, 8 patients did not return for 
follow-up testing due to the trip in the summer and 
also their work schedules.
Table 1 summarizes the results of demographics 
and clinical backgrounds which were equivalent 
(P<0.05) between the two study groups. The 
results of variance analysis showed that the group 
main effect was not significant for any primary and 
secondary outcomes (Supplementary Table). 
Therefore, there was an equivalent amount of 
improvement after the training across the both 
study groups. Moreover, there was a significant 
main effect of time for dual-10 Meter Walk test and 
dual-Timed Up and Go test but not for single-10 
Meter Walk test and single-Timed Up and Go. 
Additionally, the cognitive score of dual-10 Meter 
Walk test was not different between pre-post train-
ing while for the dual-Timed Up and Go test this 
was increased in the post-training. The results of 
pairwise comparisons for those who completed the 
follow-up testing showed that the benefits of 
improvement were maintained at follow-up test-
ing; i.e. 6-weeks after completion of the interven-
tion (P<0.01).
Discussion
As hypothesized, dual-task balance training was 
effective to improve balance performance as indi-
cated by improvement in dual-task gait speed, dual-
task Timed Up and Go time, cognitive score of 
dual-Timed Up and Go test, self-reported confi-
dence, balance and gait in patients with MS. 
However, dual-task balance training does not lead to 
any greater improvement than single-task training 
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Monjezi et al. 5
Figure 1. Flow chart of the study process.
Table 1. Demographic and functional characteristics of single- and dual-task balance training groups.
STT group (n = 19 ) DTT (n = 19) P-value
 Mean (SD) Mean (SD) (Mean differences)
Demographic data
Age (yr) 36.2 (9.16) 35.8 (6.91) 0.87
Height (m) 1.6 (0.08) 1.6 (0.06) 0.13
Body mass index (kg/m2) 22.9 (3.19) 24.3 (4.06) 0.24
Time since disease (yr) 7.5 (4.62)7.2 (5.95) 0.87
Year of education (yr) 12.4 (4.42) 13.7 (3.65) 0.31
MMSEa 29.3 (0.82) 29.1 (1.05) 0.50
EDSSb 2.7 (0.91) 2.9 (1.25) 0.42
STT: Single-task training; DTT: Dual-task training; MMSE: Mini-Mental State Examination; EDSS: Expanded Disability Status Scale.
aRange of scores is from 0 to 30.bRange of scores is from 0 to 10.
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6 Clinical Rehabilitation 
program. The results obtained in this study are con-
sistent with results of the only study conducted on 
patients with MS in which balance training under 
dual-task conditions (i.e. playing Wii exergames on 
an unstable surface) was effective as traditional bal-
ance training.10
We expected more improvement in dual-task 
group than single-task group. There are several pos-
sible reasons that might explain these results. One 
reason is related to the large variability observed for 
the amount of improvement in both study groups 
(See Table 2). For instance, while the mean differ-
ence between pretest-posttest times of the dual-10 
Meter Walk test showed an improvement of 0.07sec 
for the single-task training group and 0.13sec for the 
dual-task training group, the standard deviation of 
these differences were also high (i.e. standard devia-
tion of 0.17sec and 0.20sec for single-task and dual-
task groups, respectively). Another explanation is 
that the counting cognitive task used in dual-task 
based outcome measures of this study (i.e. dual-10 
Meter Walk test, dual-Timed Up and Go test) was 
not sufficiently difficult to compete with the atten-
tional demands of the walking tasks. Therefore, in 
future studies, we recommend a more challenging 
cognitive task (such as Stroop task) or a secondary 
motor task (such as holding a tray while walking) to 
elicit dual-task training effects on postural control. 
Finally, we found that training balance under single-
task situations resulted into the improvement in 
dual-task testing of gait and balance (i.e. dual-10 
Meter Walk test and dual-Timed Up and Go test). 
This finding supported the Task Automization 
Hypothesis17 in which practicing only postural tasks 
at a time (i.e. single-task training) allows patients to 
gain automaticity in performing that activity. As a 
result, according to the attentional capacity theory, 
the attentional demands required to perform this task 
is decreased, freeing more capacity to perform 
another task concurrently.10,17
Table 2. Outcome measurements for the pretest-posttest times in both single- and dual-task training groups.
Outcomes Pretest Posttest Difference 95% CI
 mean (SD) mean (SD) mean (SD) 
Single-task training
Single-10MW (m/s) 1.03 (0.20) 1.03 (0.18) 0.003 (0.16) −0.08 to 0.08
Dual-10MW (m/s) 0.91 (0.19) 0.98 (0.19) 0.07 (0.17) −0.01 to 0.15
Single-TUG (sec) 10.54 (1.98) 10.17 (2.19) −0.37 (1.61) −1.15 to 0.41
Dual-TUG (sec) 12.65 (2.60) 11.24 (2.87) −1.40 (1.55) −2.15 to −0.66
ABC (0-100 point) 57.26 (20.54) 64.05 (18.53) 6.79 (13.99) 0.05 to 13.53
BBS (0-56 point) 44.32 (6.49) 48.42 (4.43) 4.11 (5.38) 1.51 to 6.7
FGA (0-30 point) 17.05 (5.63) 20.68 (4.46) 3.63 (3.27) 2.06 to 5.21
Cog score of dual-10MW 5.53 (1.95) 5.74 (1.85) 0.21 (1.36) −0.45 to 0.87
Cog score of Dual-TUG 4.82 (1.33) 5.00 (1.52) 0.18 (1.55) −0.56 to 0.93
Dual-task training
Single-10MW (m/s) 1.04 (0.29) 1.06 (0.30) 0.02 (0.16) −0.06 to 0.10
Dual-10MW (m/s) 0.81 (0.29) 0.94 (0.33) 0.13 (0.20) 0.04 to 0.23
Single-TUG (sec) 10.27 (4.67) 9.52 (4.21) −0.75 (2.67) −2.04 to 0.54
Dual-TUG (sec) 12.30 (5.37) 10.87 (4.21) −1.43 (2.88) −2.82 to −0.04
ABC (0-100 point) 60.21 (17.51) 68.21 (14.86) 8 (16.74) −0.07 to 16.07
BBS (0-56 point) 45 (4.15) 49.26 (3.53) 4.26 (3.83) 2.42 to 6.11
FGA (0-30 point) 18.84 (4.71) 20.89 (4.93) 2.05 (3.19) 0.52 to 3.59
Cog score of dual-10MW 6.05 (3.06) 5.93 (2.57) 0.12 (2.69) −1.42 to 1.17
Cog score of dual-TUG 4.12 (1.49) 4.91 (1.41) 0.79 (1.11) 0.25 to 1.32
SD: standard deviation; CI: confidence interval.10MW: 10m walk test; TUG: time up and go; ABC: activities-specific balance 
confidence; BBS: berg balance scale; FGA: functional gait assessment.
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Monjezi et al. 7
The results of this study showed that in contrast 
to single-task testing of balance and gait, testing 
under dual-task conditions was able to discriminate 
differences between pretest-posttest times. This 
finding suggests that the postural performance 
measures under dual-task conditions are more sen-
sitive to record the training effects than postural 
measurements in isolation.3, 6 Therefore, in contrast 
to single-task measures of postural performance, 
the outcome measures based on dual-tasking, may 
represent a promising tool for detecting the training 
effects, since they truly reflect everyday activities 
compared to assessing postural and cognitive 
skills, separately.1 This hypothesis is supported by 
evidences that fall risks are increased in activities 
performed under cognitive loading in patients with 
MS.22,23 Consistent with finding of our study, 
Nilsagard et al. observed that the Nintendo Wii Fit 
balance exercise improved the dual-Timed Up and 
Go test not the single-Timed Up and Go in patients 
with MS.6 Also, these authors in an observation 
study performed on 70 patients reported that the 
performance of dual-Timed Up and Go test was a 
predictor for future falls in MS.23
This study has several strengths in terms of the 
interpretation of the findings. First, one of the 
important issues in randomized controlled trials is 
whether the positive training effects are retained 
several months after the end of training. We 
included a follow-up period after the end of inter-
vention to assess the long-term effects of the bal-
ance program and found that the balance training 
effects were maintained at 6-weeks follow-up. 
Second, a posttest analysis was performed for 80% 
of the patients enrolled into the study. As most 
drop-out was due to their work schedules, we rec-
ommend fewer treatment sessions for encouraging 
patients to complete the treatment plan. Third, we 
conducted a double-blind study in which both the 
patients and examiner were blinded to the group 
assignment.
We acknowledge the following study limitations. 
While in the single-center study we can include 
more homogenous sample, a sufficient large sample 
size may not possible in this case. Therefore, a first 
limitation of this study is that commonly observed in 
pilot rehabilitation studies (i.e. small sample size) 
that limits the generalizability of the results and 
reduces the observed power to detect a true differ-
ence. A post-study calculation showed that a sample 
of 71 patients per group would be needed to be ade-
quately powered to determine if there is any differ-
ence for dual-task gait speed (as an example) 
between the two groups. Second; our sample com-
prised patients with mild to moderate disability (as 
indexed by the Expanded Disability Status Scale), 
so the findings cannot be generalized to patients 
with a more severe disability. Third, due to the ethi-
cal considerations, there was no true control group 
with no exercise program. Another limitation may 
be not assessing falls-related outcome measures in 
this study. As falls is affected by postural instability, 
many patients with MS reported falls as a common 
concern.24 Therefore, future research should evalu-
ate falls outcome measures when training balance in 
patients with MS.
Overall, this pilot study did not show any bene-
fit from undertaking dual-task balance training. A 
power analysis showed that a sample of 71 patients 
per group would be needed to determine whether 
there was a clinically relevant difference for dual-
task gait speed between the groups.
Clinical Messages
•• Dual-task balance training does not lead 
to any greater improvement than single-
task training program.
•• Outcome measuresbased on dual-task-
ing are more sensitive to detect the train-
ing effects than postural measurements in 
isolation.
Acknowledgements
This study is part of MSc thesis of Mrs. Monjezi. Special 
thanks to Ahvaz Jundishapur University of Medical 
Sciences for the financial support.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest 
with respect to the research, authorship, and/or publica-
tion of this article.
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8 Clinical Rehabilitation 
Funding
The author(s) disclosed receipt of the following financial 
support for the research, authorship, and/or publication of 
this article: This work was supported by a Master thesis 
grant (no: PHT-9229) in Ahvaz Jundishapur University 
of Medical Sciences, Ahvaz, Iran
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