doi: 10.2490/prm.20180016

Progress in Rehabilitation Medicine 2018; Vol. 3, 20180016

ORIGINAL ARTICLE

Safety and Feasibility of Dual-task Rehabilitation Programfor Body Trunk Balance Using Virtual Reality andThree-dimensional Tracking Technologies
Masahiko Hara, MD, PhD a, b Tetsuhisa Kitamura, MD, MSc, DrPH c Yuichiro Murakawa, OT, MHSc d
Kyosuke Shimba b Shimpei Yamaguchi b and Masatake Tamaki, MCMS b
Objective: The ability to walk is one of the most important basic functional activities of dailyliving, and the number of patients with walking disability who need rehabilitation is increasing worldwide. The purpose of this first-in-man study was to evaluate the safety and feasibilityof an off-label, tailor-made, dual-task rehabilitation program for body trunk balance using themediVR01 system (mediVR, Inc. Osaka, Japan), which incorporates virtual reality (VR) andthree-dimensional tracking technologies. Methods: We prospectively enrolled 31 healthy volunteers to take part in the trial (Trial Registration UMIN000029659). After an assessment of bodytrunk balance, a tailor-made, dual-task, rehabilitation training program lasting 10–15 min wasprovided. The primary endpoint was the postprocedural number of simulator sickness questionnaire (SSQ) symptoms. The secondary endpoints were adverse events and satisfaction with theprogram. Results: The median age of participants was 68 years, with 67.7% being elderly (>65
years) and 54.8% being male. The number of SSQ symptoms immediately after the rehabilitation
programs significantly increased from 0 (interquartile range 0–0) to 0 (0–1.5) (P=0.009), witha significant difference between the young and elderly participants (P-interaction<0.001). The
most frequent symptom was sweating (22.6%), followed by fatigue (19.4%). All participants successfully completed the rehabilitation programs without significant adverse events such as fall or
injuries. Moreover, all participants considered the VR rehabilitation programs to be enjoyable,
and 93.5% of participants reported a sense of achievement. Group attendance was associatedwith higher levels of satisfaction (P=0.049). Conclusion: The tailor-made, dual-task rehabilitation
training programs for body trunk balance using VR and three-dimensional tracking technologies
were safe and feasible even for elderly participants.
Key words: body trunk balance; dual-task rehabilitation; first-in-man; mediVR01; virtual reality

INTRODUCTION

effect.1–6) As the world’s population ages, the number ofpatients with walking disability increases. In many countries, this may result in a demand–supply mismatch in theclinical setting caused by inadequate human resources, suchas insufficient numbers of physical therapists or caregivers,or problems with the costs of home and outpatient healthcare.2,7–9)

The ability to walk is one of the most important basic functional activities of daily living (ADLs). This ability can be
impaired by various conditions, including cerebrovasculardiseases such as stroke, neurodegenerative diseases such as
Parkinson’s disease and dementia, sarcopenia, and frailty; ingeriatric patients, even hospitalization can have an adverse

Received: July 26, 2018, Accepted: October 15, 2018, Published online: October 24, 2018a Center for Community-based Healthcare Research and Education, Shimane University, Izumo, Japanb Department of Medical Device Development, mediVR, Inc., Osaka, Japanc Division of Environmental Medicine and Population Sciences, Department of Social and Environmental Medicine, Osaka University
Graduate School of Medicine, Suita, Japand Division of Stroke Rehabilitation, National Cerebral and Cardiovascular Center Hospital, Suita, Japan
Correspondence: Masahiko Hara, MD, PhD, Center for Community-based Healthcare Research and Education, Shimane University,
223-8 Enya-cho, Izumo, Shimane 693-8501, Japan, E-mail: hara@japanscr.org
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Hara M, et al: Virtual Reality Rehabilitation for Body Trunk Balance

To maintain or regain walking ability so that ADLs canbe performed safely, exercise rehabilitation focusing on bodytrunk balance and muscle strengthening of the lower extremities is recommended by international guidelines, suchas those for stroke survivors.10) Whereas, muscle strengthening can be provided using a fixed program, it is difficult toprovide tailor-made rehabilitation programs for body trunkbalance without an experienced physical therapist because
real-time quantitative instructions and tools for concomitantassessment are lacking.8,11) Moreover, exercise rehabilitation
programs should ideally use technology also to stimulate thecognitive function to help prevent falls (so-called “dual-task”
training) and should include an element of entertainment todiscourage discontinuity or withdrawal from the rehabilitation intervention.12–17)
To meet these ideal criteria for body trunk balance training, we developed a tailor-made, dual-task, rehabilitation
training program using virtual reality (VR) and threedimensional tracking technologies to provide patients withan exercise rehabilitation program with an element of gamification. This study aimed to evaluate the safety and feasibilityof this approach by focusing on the incidence of VR sickness
in subjects using a new off-label VR rehabilitation training
program for body trunk balance, namely the mediVR01.
METHODS

Participant Involvement

This study was a prespecified phase I clinical study that
aimed to evaluate the safety and feasibility of an off-label
medical device, the mediVR01 (mediVR, Inc., Osaka, Japan). The mediVR01 provides patients with a standardized,
tailor-made, dual-task exercise rehabilitation program forbody trunk balance using VR and three-dimensional tracking technologies (HTC Vive®, HTC Corporation, New Taipei
City, Taiwan). All subjects were healthy adult volunteers, andthe exclusion criteria were a medical history of (1) vertigo,
dizziness, Meniere’s disease, or other semicircular canal or
inner ear problems; (2) untreated poor vision; (3) epilepsy;(4) postural dizziness or hypotension; (5) participation inanother clinical study within 3 months; (6) and psychiatricdisorder or loss of the ability to understand; (7) further,volunteers considered to be inappropriate candidates basedon the attending physician’s discretion were also excluded.
Of 33 healthy volunteers enrolled between November 1
and December 28, 2017, one volunteer disagreed with our
privacy policy and another candidate with Meniere’s disease
met one of the exclusion criteria of the present study. Finally

31 participants completed the study and enrolled in the final
analysis. The study protocol complied with the standards ofthe Declaration of Helsinki and was approved by the Ethics Committee of the Japan Society of Clinical Research(approval number 201706). Written informed consent was
obtained from all study participants, and participants were
informed that the study results would be disseminated as ajournal article. This study was registered at the University
Hospital Medical Information Network Clinical Trials Registry (UMIN000029659) and meets the criteria of the International Committee of Medical Journal Editors (ICMJE).

Study Protocol

As shown in Fig. 1A, participants sit on an upright chair,wear a head-mounted display (HMD) and a central tracker
located near the supraclavicular fossa, and grasp two handheld controllers. The VR system locates participants ina motion-tracked three-dimensional space called “roomscale” of the HTC Vive set. HTC Vive can provide users
with graphics at >90 frames/s (fps) with an approximately
110° viewing angle and includes accurate three-dimensional
tracking technology.
For calibration, we evaluated conventional reaching
distances (colored blue in Fig. 1A and 1B) and maximum
reaching distances (colored red in Fig. 1A and 1B) at 0°,45°, and 90° for the left hand (0L, 45L, and 90L) and at 90°,135°, and 180° for the right hand (90R, 135R, and 180R)
with the subject in the sitting position. Conventional reaching distances were measured with each hand level with theshoulders, as shown in Fig. 1C. The maximum reaching distance was measured with the hands at the same level but withthe subject reaching as far possible, as shown in Fig. 1B.
Participants were then instructed to catch a virtual squarebox at the thoracic level (Fig. 1C). The box fell from a 3 mheight at pre-determined horizontal distances tailor-madefor each participant. The horizontal distances were classified
into two categories, namely long and middle, and were calculated using the following formulas: 0.9 * maximum reaching distance and 0.9 * (conventional + maximum reaching
distances)/2, respectively. If the participant failed to catch avirtual square box, for safety reasons, the box disappeared
at a height of 20 cm above the floor. The censoring area ofthe square box was 4 cm per side for measurement accuracy,
and this was indicated by an outlined pale box with 20 cm
on a side for visibility. The censoring area of the handheld
controllers had a 2 cm spherical diameter. The purpose of thereaching tasks was to stimulate body trunk balance, and to
train participants to balance for stable walking. During the

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3Prog. Rehabil. Med. 2018; Vol.3, 20180016

Fig. 1. Concepts of the mediVR01 system. After assessment of the subject’s body trunk balance (A and B), a tailor-maderehabilitation training program was provided with the subject in the sitting position (C). The purpose of reaching with thehands was to stimulate body trunk balance and to train participants to balance. With VR and three-dimensional tracking
technologies, the stimulation inputs for body trunk balance could be quantitatively provided by setting the reaching distances. Cognitive function was also stimulated to provide dual-task training in a uniform VR environment.
program, the direction and horizontal distance of the box in
the following task was indicated by the HMD. We expectedthat the provision of this information would cause the participants to internalize the nature of the next task and would
therefore result in a higher success rate. By repeatedly allowing the participants to think about the timing and distanceof the next target, cognitive function was simultaneously
stimulated to provide dual-task training.12–14) We measured
the horizontal distances for each handheld controller and thecentral tracker during each training exercise to evaluate theachievement rate for each task. We thereby provided participants with quantitative information about trunk control
and quantitatively evaluated their achievement for each task
during the tailor-made, dual-task, rehabilitation training
program.
The four parameters of the rehabilitation programs in thepresent study were as follows: (1) distance (middle or long),(2) direction (0L, 45L, 90L, 90R, 135R, or 180R), (3) falling
speed of the square box (55 or 75 cm/s), and (4) the interval
between tasks (1, 3, or 5 s). To provide another parameter forcognitive function stimulation, it is possible to change thesize of the center or outline of the falling box or the sensing

sphere. However, these sizes were fixed in the present study.
Participants first underwent two practice rehabilitation
programs to familiarize themselves with VR rehabilitation,
followed by two exercise rehabilitation programs (normal
and hard). If participants could understand how to use thesystem after the first practice rehabilitation program, the second practice program could be skipped. Detailed protocols
are shown in Table 1. Elderly participants (≥65 years old)
required approximately 15 min to complete all the programs,
whereas young participants took 10 min. If a falling squarebox was caught by the participant, the task was recorded as a
success. For each subject, we evaluated the total success ratesof Exercise 1 and Exercise 2 as defined in Table 1. Provisionof the rehabilitation programs was either personalized or ingroups. In group sessions, three or more participants came
together, with one undergoing the rehabilitation program
while the other participants observed. To prevent subjects
falling from the chair, safety management was provided by acaregiver positioned by the participant during the rehabilitation session.

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4Hara M, et al: Virtual Reality Rehabilitation for Body Trunk Balance

Table 1. Practice and exercise rehabilitation programs carried out using the mediVR01 system
ProgramPractice 1

Falling speed
Elderly 55 cm/s
Young 75 cm/s

Interval
5s

ProtocolMiddle distance
0L–0L–45L–45L–90L–90L–180R–180R–135R–135R–90R–90R
Long distance
0L–0L–45L–45L–90L–90L–180R–180R–135R–135R–90R–90R
Practice 2
Elderly 55 cm/s
3s
24
Middle distance
Young 75 cm/s
0L–0L–45L–45L–90L–90L–180R–180R–135R–135R–90R–90R
Long distance
0L–0L–45L–45L–90L–90L–180R–180R–135R–135R–90R–90R
Exercise 1
Elderly 55 cm/s
3s
24Long distance(normal)Young 75 cm/s
90R–0L–135R–45L–180R–90L–135R–0L–90R–45L–135R–90L–
180R–0L–90R–45L–180R–90L–135R–0L–90R–45L–180R–90L
Exercise 2
Elderly 55 cm/s
1s
24Long distance(hard)
Young 75 cm/s
90R–0L–135R–45L–90R–0L–135R–90L–180R–45L–180R–90L–
180R–0L–135R–90L–135R–45L–90R–0L–90R–45L–180R–90L
Each program had four parameters: (1) horizontal distance (middle or long), (2) direction (0L, 45L, 90L, 90R, 135R, or
180R), (3) falling speed of the square box (55 or 75 cm/s), and (4) the interval between tasks (1, 3, or 5 s). Participants firstunderwent two practice rehabilitation programs to familiarize themselves with VR rehabilitation. This was followed by two
exercise rehabilitation programs (normal and hard). 0L, 45L, and 90L are orientations of 0°, 45°, and 90° for the left hand,whereas 90R, 135R, and 180R are orientations of 90°, 135°, and 180° for the right hand.

Endpoints and Statistical Analysis

Tasks
24

The primary endpoint was the safety of mediVR01, which
was evaluated based on the number of simulator sickness
questionnaire (SSQ) symptoms.18) SSQ was administered
before, immediately after, and 3 days after the VR rehabilitation programs. SSQ consisted of 16 parameters that were
each evaluated in four categories: none, slight, moderate,and severe.18) The secondary endpoints were adverse events(such as falls from the chair, any injuries, or unexpected discontinuation of the rehabilitation program) and the feasibilityof mediVR01, which was evaluated using a five-point Likert
scale questionnaire on satisfaction and sense of achievement.
These secondary endpoints may reflect the overall severityof SSQ symptoms and describe the degree of safety. Continuous variables were summarized using medians and interquartile ranges (IQRs, quartiles 1 to 3), whereas categoricalvariables were summarized using counts and percentages.
The statistical significance of the pre- and postprocedural
number of SSQ symptoms in each participant was evaluatedusing the Wilcoxon signed-rank test considering parity. We
defined elderly participants as those aged ≥65 years. The Pinteraction between the elderly and young participants was
also evaluated using linear regression analysis by including
the postprocedural number of symptoms as the objective
variable and preprocedural number of symptoms as the
explanatory variable, with the elderly participants as theinteraction term. Differences in the prevalence of second-ary endpoints between the elderly and young participants
or types of attendance were evaluated using the chi-square
test. All statistical analyses were performed using Microsoft
R Open Software (version 3.3.2, Microsoft Corporation,
Redmond, WA, USA).
RESULTS
Participant characteristics are shown in Table 2. The median age was 68 years (IQR 57–73 years), with 67.7% being
elderly and 54.8% being male. None had used a VR device
before the study, and 32.3% wore eyeglasses. Eleven (35.5%)
participants had experienced car sickness in their daily life,
9 (29.0%) played video or smartphone games, and 20 (64.5%)
underwent the rehabilitation program in groups.
The total success rate for the normal exercise rehabilitation program defined as Exercise 1 in Table 1 was 95.8%(85.4%–100.0%). There was a statistically significant difference between the elderly and young participants (87.5%[75.0%–95.8%] vs. 100.0% [96.9%–100.0%]; P=0.005). In
contrast, the total success rate for the hard exercise rehabilitation program, defined as Exercise 2 in Table 1, was45.8% (33.3%–58.3%). There was no statistically significant
difference between the elderly and young participants (45.8%[33.3%–58.3%] vs. 54.2% [39.6%–57.3%]; P=0.497).
With respect to the primary endpoint (Table 3), thepostprocedural number of SSQ symptoms, especially the

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5Prog. Rehabil. Med. 2018; Vol.3, 20180016

75th percentile value, significantly increased from 0 (0–0)
to 0 (0–1.5) (P=0.009). Furthermore, there was a significant
difference in the postprocedural number of SSQ symptoms
between young participants (from 0 [0–0] to 1 [0–2.75]) andelderly participants (from 0 [0–0] to 0 [0–0]) (interaction effect, P<0.001). All SSQ symptoms were reported to be slight,
except for those in the youngest participant (29 years old),
who had preprocedural symptoms of slight fatigue and hadslight eyestrain and who, after rehabilitation, had moderate
eyestrain, moderate difficulty in focusing, moderate sweating, moderate blurred vision, and moderate stomach awareness. The most frequent symptom was sweating (22.6%),
followed by fatigue (19.4%), eyestrain (12.9%), difficulty infocusing (12.9%), and blurred vision (12.9%). However, subsequently, all SSQ symptoms improved, and no participants
showed any SSQ symptom 3 days after the rehabilitation
program.
With respect to the secondary endpoints, no falls fromthe chair or injuries occurred. One 72-year-old participant
unexpectedly discontinued the rehabilitation program because he unintentionally pushed the emergency stop button,with which the device was equipped for safety reasons. He
then redid the normal exercise rehabilitation program after
a computer reboot; the total procedural time was extended
to 20 min (i.e., an additional 5 min). Consequently, all participants completed the rehabilitation programs without any
adverse events. Figure 2 shows the results of the five-point
Likert scale questionnaire survey on satisfaction and senseof achievement. All participants considered the VR rehabilitation programs to be enjoyable, and the majority (93.5%)
reported a sense of achievement. However, some participants
complained about the short duration of the rehabilitation programs. Interestingly, group attendance was associated withhigher satisfaction levels (P=0.049).
DISCUSSION
In the present study, we evaluated the safety and feasibility of a new off-label medical device intended to improve
body trunk balance. The device provided participants with astandardized, tailor-made, dual-task, exercise rehabilitation
program with a level of gamification. The main findings wereas follows: (1) The number of SSQ symptoms significantly
increased immediately after the rehabilitation program, andthis was mainly attributable to increased symptoms in young
participants. (2) All participants successfully completed therehabilitation programs without any adverse events suchas falls or injuries. (3) All participants considered the VR

rehabilitation programs to be enjoyable, despite their lack ofprevious VR experience, and most participants reported asense of achievement. (4) Group attendance was associatedwith higher satisfaction levels.

VR-induced Sickness Assessed by SSQ

To provide participants with quantitative instructions
and to quantitatively evaluate achievements, we employed
VR and three-dimensional tracking technologies. The mostimportant safety problem of VR in the clinical setting is VRinduced sickness, which is believed to occur as a result of
discrepancies among sensory inputs, such as those between
visual and vestibular senses, known as sensory conflict.19)
To minimize VR-induced sickness, we selected HTC Vivebecause its HMD can operate at >90 fps, which may besufficient to avoid frame delay and visual lag during therehabilitation program.19) In our rehabilitation program, we
fixed the landscape to avoid sensory conflict and stimulated
the cognitive function using the following four parameters of
the falling box: horizontal distance, direction, falling speed,
and interval between tasks. Even with these efforts to minimize VR-induced sickness, the number of SSQ symptoms
significantly increased immediately after the rehabilitation
program, and this was mainly attributable to an increase in
symptoms in young participants. However, we believe thatthe two most frequent SSQ symptoms, namely sweating andfatigue, are natural responses to exercise rehabilitation and do
not require caution in our view. Therefore, one of the important lessons from our study with respect to VR-induced sickness is that we need to exercise caution during rehabilitation,
especially when providing programs for young participants.
The increase in SSQ symptoms in younger participants may
partly be explained by their tendency to become enthusiastic
to successfully catch the square boxes.
We intentionally provided an exercise rehabilitation program within a field greater than the 110° field of view of the
HTC Vive HMD because restricting the body trunk balance
exercises within 110° is not realistic in the clinical setting.
For example, several tasks such as 0L–135R or 180R–0L
need body trunk balance at 135° or 180°, respectively. It is
possible that this type of exercise rehabilitation program
may have elicited sensory conflict and resulted in increased
SSQ symptoms in this study. Increasing the field of view of
the VR HMD could potentially result in a reduction in VRinduced sickness in the future.

Other Safety Problems

To safely operate a standardized rehabilitation program

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6Hara M, et al: Virtual Reality Rehabilitation for Body Trunk Balance

Table 2. Participant characteristics
Parameter
n=31
Age, years
68 (57–73)
Elderly (≥65 years old)21 (67.7)Male
17 (54.8)
Height, cm
160 (155–166)
Weight, kg
61.0 (50.8–72.5)
Previous VR experience
0 (0.0)Wearing eyeglasses
10 (32.3)
Vision problem (questionnaire)
Myopia12 (38.7)
Hyperopia
3 (9.7)
Astigmatism
8 (25.8)
Presbyopia
12 (38.7)
Car sickness
Often
1 (3.2)
Sometimes
4 (12.9)
Rarely6 (19.4)
Never
20 (64.5)
Playing video/smartphone games
Often
0 (0.0)Sometimes
4 (12.9)
Rarely5 (16.1)
Never
22 (71.0)
Type of attendance
Personalized
11 (35.5)
Group (≥three participants)
20 (64.5)
Continuous variables are given as medians and interquartile ranges, whereas categorical variables are summarized using counts and percentages.
VR, virtual reality.
without human medical resources, our program was executedwith the participants sitting on an upright chair, rather thanstanding. The rationale for this was the fact that two-thirdsof the total body weight is centered in the upper body, which
results in inherent balance instability in humans.20) Consequently, we speculated that upper body balance training,
even in a sitting position, may exhibit reasonable degrees ofboth efficacy and safety, although efficacy was not evaluatedin this study. All participants successfully completed therehabilitation programs without significant adverse events
such as fall or injuries. We believe that the disappearanceof the square boxes at a height of 20 cm also contributed tosafety.
To proactively evaluate the safety of our exercise rehabilitation program, participants finished with a hard exercise
rehabilitation program (Table 1) that was expected to bevery difficult to deal with. As anticipated, the overall successrate for the hard exercise rehabilitation program, defined as
Exercise 2 in Table 1, was less than 50%, and there was no
statistical difference between the elderly and young participants. This finding suggests that our exercise rehabilitation
program was intentionally interruptible and did not result inadverse events such as a fall.

Feasibility Evaluation

Contrary to our expectations, all participants, including
the elderly, found the VR rehabilitation programs enjoyable,
despite their lack of previous VR experience. Compared withthe young participants, the elderly participants tended toconsider the VR rehabilitation programs as very enjoyable,
although the difference was not statistically significant. The
reason for this may have been that our main targets were the

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7Prog. Rehabil. Med. 2018; Vol.3, 20180016

Table 3. Results of the simulator sickness questionnaire survey
Before VR rehabilitation
programs
0 (0–0)0 (0–0)0 (0–0)

Immediately after VR
Three days after VR
rehabilitation programs rehabilitation programs
0 (0–1.5)
0 (0–0)0 (0–0)0 (0–0)1 (0–2.75)
0 (0–0)No. of symptoms in each participant
Elderly
Young
Detailed components
1. General discomfort
0 (0.0)2 (6.5)0 (0.0)2. Fatigue
1 (3.2)6 (19.4)
0 (0.0)3. Headache
0 (0.0)0 (0.0)0 (0.0)4. Eyestrain
1 (3.2)4 (12.9)
0 (0.0)5. Difficulty in focusing
1 (3.2)4 (12.9)
0 (0.0)6. Increased salivation
0 (0.0)1 (3.2)0 (0.0)
7. Sweating
0 (0.0)7 (22.6)
0 (0.0)8. Nausea
0 (0.0)0 (0.0)0 (0.0)9. Difficulty in concentrating
0 (0.0)0 (0.0)0 (0.0)10. Fullness in the head
0 (0.0)1 (3.2)0 (0.0)11. Blurred vision
2 (6.5)4 (12.9)
0 (0.0)12. Dizziness with eyes open
0 (0.0)3 (9.7)0 (0.0)13. Dizziness with eyes closed
0 (0.0)1 (3.2)0 (0.0)14. Vertigo
0 (0.0)1 (3.2)0 (0.0)15. Stomach awareness
0 (0.0)1 (3.2)0 (0.0)16. Burping
0 (0.0)0 (0.0)0 (0.0)Continuous variables are given as medians and interquartile ranges, whereas categorical variables are summarized using
counts and percentages.
All symptoms were reported to be "slight," except for those in a 29-year-old man with preprocedural symptoms of slight fatigue and slight eyestrain who had moderate eyestrain, moderate difficulty in focusing, moderate sweating, moderate blurredvision, and moderate stomach awareness immediately after rehabilitation.
elderly participants, and the normal exercise rehabilitation
program was likely too easy or left much to be desired forthe young participants, as suggested by the very high successrate. Furthermore, we showed that group attendance was associated with higher satisfaction. It appears that the conceptof mutual-help group participation, applied as a treatment
strategy for alcohol or drug abuse, may also be applicable tothe field of rehabilitation.21,22)

Clinical Implication

Recently, gamification has been widely introduced into
many medical disciplines, especially in the digital healthcare
fields, including e-learning and self-administered physicaltraining programs.16,17) Moreover, the remarkable success of
the augmented reality game Pokémon GO (Niantic, Inc., San
Francisco, CA, USA), which might inadvertently contributeto public or psychiatric health, shows the potential for the
new healthcare approach of entertainment with a hidden
healthcare agenda.23–25)

Study Limitations

This study has several limitations that should be consideredduring data interpretation. First, the number of participants
is low. Second, a significant selection bias exists because
enrolments were made based on voluntary participation.
Lastly, we did not evaluate the efficacy of the mediVR01
system in this study. Some physicians have suggested thatthe use of two-dimensional programs, such as Nintendo Wii
Fit™ (Nintendo, Kyoto, Japan), that encourage physical activities or exercise, cannot with certainty lead to an intended
therapeutic effect. The reason they give is the inability ofsuch programs to provide accurate instructions and quantitative assessments, despite such programs exhibiting a certain
level of efficacy, especially on Berg balance scores and thetimed-up-and-go test, and despite their very high levels ofsafety and feasibility (similar to those found in the current
study).17,26,27) However, our novel quantitative tailor-maderehabilitation approach has the potential to resolve thisproblem by providing accurate instructions and quantitative

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8Hara M, et al: Virtual Reality Rehabilitation for Body Trunk Balance

Fig. 2. Satisfaction and sense of achievement. Results of a 5-point Likert scale questionnaire on satisfaction (A–E) and sense of achievement (F–J).
assessments. The efficacy and effect of our system on the recovery of walking ability, the alleviation of human resource
problems, and cost reduction are pertinent issues for future
research.

CONCLUSIONS
Our tailor-made, dual-task rehabilitation training programfor body trunk balance using VR and three-dimensional
tracking technologies was safe and feasible, even for elderly
participants.

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Prog. Rehabil. Med. 2018; Vol.3, 20180016

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MH, Fowkes FG, Fransen M, Freeman MK, Gabbe BJ,
Gabriel SE, Gakidou E, Ganatra HA, Garcia B, Gaspari F, Gillum RF, Gmel G, Gonzalez-Medina D, Gosselin R, Grainger R, Grant B, Groeger J, Guillemin F,
Gunnell D, Gupta R, Haagsma J, Hagan H, Halasa YA,

This research received no specific grant from any funding
agency in the public, commercial, or not-for-profit sectors.
CONTRIBUTORSMasahiko Hara, Tetsuhisa Kitamura, Yuichiro Murakawa,
Kyosuke Shimba, Shimpei Yamaguchi, and Masatake Tamaki (1) provided substantial contributions to the conception
or design of the study or the acquisition, analysis, or interpretation of data; (2) drafted the paper or revised it criticallyfor important intellectual content; (3) provided final approvalof the version to be published; and (4) agreed to be accountable for all aspects of the work in ensuring that questions
related to the accuracy or integrity of any part of the work
are appropriately investigated and resolved.
CONFLICT OF INTEREST
Masahiko Hara, Kyosuke Shimba, Shimpei Yamaguchi,
and Masatake Tamaki are stock holders of mediVR, Inc.,a company with unlisted stock and ongoing international
Patent Cooperation Treaty applications that holds a patenton dual-task training and updating the target value of rehabilitation based on achievement rates (patent no. 6200615
in Japan). However, this research received no specific grantfrom any funding agency in the public, commercial, or notfor-profit sectors.
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