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Annals of Rehabilitation Medicine
Original Article
Ann Rehabil Med 2015;39(6):957-963
pISSN: 2234-0645 • eISSN: 2234-0653
http://dx.doi.org/10.5535/arm.2015.39.6.957
Received May 14, 2015; Accepted July 1, 2015
Corresponding author: Si-Bog Park
Department of Rehabilitation Medicine, Hanyang University Medical Center, Hanyang University College of Medicine, 222-1 Wangsimni-ro,
Seongdong-gu, Seoul 04763, Korea
Tel: +82-2-2290-9226, Fax: +82-2-2290-9231, E-mail: sibopark@hanyang.ac.kr
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/
licenses/by-nc/4.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Copyright © 2015 by Korean Academy of Rehabilitation Medicine
Relief of Chronic Posterior Neck Pain Depending
on the Type of Forest Therapy: Comparison of
the Therapeutic Effect of Forest Bathing Alone
Versus Forest Bathing With Exercise
Boram Kang, MD
1
, Taikon Kim, MD, PhD
1
, Mi Jung Kim, MD, PhD
1
, Kyu Hoon Lee, MD, PhD
1
,
Seungyoung Choi, MD
1
, Dong Hun Lee, MD
1
, Hyo Ryoung Kim
2
, Byol Jun, MA
2
,
Seen Young Park
2
, Sung Jae Lee, MD, PhD
2
, Si-Bog Park, MD, PhD
1
1
Department of Rehabilitation Medicine, Hanyang University College of Medicine, Seoul;
2
Department of Integrative Medicine, Korea University College of Medicine, Seoul, Korea
Objective
To compare the pain-reducing effect of forest bathing alone versus forest bathing in combination with
stretching and strengthening exercises in patients with chronic posterior neck pain.
Methods
Sixty-four subjects with posterior neck pain that had lasted more than 3 months were enrolled. They
were randomly divided into a forest bathing alone (FBA) group and a forest bathing with exercise (FBE) group;
each group included 32 subjects. All subjects from both groups walked every morning in the forest for about 2
hours for 5 days. In the afternoon, the FBE group did a stretching and strengthening exercise for about 4 hours;
the FBA group had free time in the woods. Visual analog scale (VAS) on one day, VAS over the previous week, neck
disability index (NDI), EuroQol 5D-3L VAS (EQ VAS) and index (EQ index), McGill pain questionnaire (MPQ), the
number of trigger points in the posterior neck region (TRPs), and the range of motion of the cervical spine were
evaluated on the first and last day of the program and compared between the two groups.
Results
The number of TRPs were significantly reduced in the FBE group compared with the FBA group (p=0.013).
However, the other scales showed no significant difference between the two groups.
Conclusion
When patients with chronic posterior neck pain underwent a short-term forest bathing (less than 7
days) program, FBE was more effective in the reduction of the number of TRPs than FBA. However, all other pain
measurement scales we evaluated showed no statistically significant difference between the two protocols.
Keywords
Neck pain, Exercise therapy, Chronic pain, Musculoskeletal pain, Complementary therapies
Boram Kang, et al.
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INTRODUCTION
Posterior neck pain is a common complaint; it affects
70% of individuals at some time in their lives [1,2]. In
many cases, it is difficult to pinpoint the cause of the
pain. In cases where the underlying disease is not diag-
nosed and treated in the early stages, pain often does
not respond well to general treatment and, as a result,
the medical and socioeconomic costs of treatment can
be very high. Indeed, the mechanism and role of chronic
pain is different from that of acute pain. The major role
of acute pain is the protection of the body from damage
by noxious stimuli present in the external environment.
On the contrary, chronic pain has more complex causes
such as central nervous system damage, injury, or psy-
chosocial problems, and it often has the characteristics of
a pathological state rather than those of a physiological
state [3]. Understanding of the importance of psychoso-
cial factors such as affective and cognitive problems as a
cause of chronic pain has gradually increased.
Although medication, surgical treatment, physical mo-
dalities, cervical traction, epidural injection, etc. have
been applied for the purpose of treating posterior neck
pain, there is seldom an optimal treatment, except in the
case of surgical treatment for patients with specific con-
ditions [4,5]. Because of the limitations of existing treat-
ments, many complementary treatments have been sug-
gested and researched. For instance, one study addressed
pain reduction and increase in cervical range of motion
(C-ROM) following dry needling and acupuncture in 36
patients with chronic neck pain [4]; another examined
the pain-reducing effect of botulinum toxin A injection in
50 chronic neck pain patients [6]. However, no comple-
mentary treatments have been shown to be superior to
existing medical interventions.
Recently, many studies on the therapeutic effects of the
forest have been reported. A study in Japan showed an
increase of natural killer cell activity after 3 days of forest
bathing which lasted for a month [7]. A study comparing
the physiological and psychological effects of forest ver-
sus urban environments on young male adults showed
positive effects of forest bathing on physical and psy-
chological health [8]. Several studies about the effects of
forest bathing have been also reported in South Korea.
Forest bathing was reported to have a positive impact
on blood pressure and salivary cortisol level in elderly
patients with hypertension [9] and therapeutic effects in
patients with psychological problems such as anxiety, de-
pression, and stress [10-12]. As far as we knew, however,
a therapeutic effect of forest bathing on musculoskeletal
pain had not yet been reported. Therefore, we previously
conducted a preliminary study to address whether for-
est bathing may ameliorate chronic posterior neck pain
and showed significantly reduced pain in a forest bathing
group compared with a group going about daily life in a
city. On the basis of this result, we hypothesized that for-
est bathing plus stretching and strengthening exercises
targeted to the muscles in the cervical and shoulder re-
gions would have a superior therapeutic effect compared
with forest bathing alone; it has been shown that stretch-
ing and strengthening exercises are helpful for relieving
posterior neck pain [13]. The therapeutic effect of exer-
cise on neck pain is most likely because posterior neck
pain may result in reflexive protective muscle spasms and
decreased ROM, regardless of the primary cause of pain
[14].
To test our hypothesis, we herein compare the pain-re-
ducing effects of forest bathing alone versus forest bath-
ing plus stretching and strengthening exercises targeted
to the muscles of the cervical and shoulder regions.
MATERIALS AND METHODS
For one month in May 2013, 70 subjects who visited the
Department of Rehabilitation Medicine of Hanyang Uni-
versity Medical Center and met certain inclusion criteria
were recruited through a notice in the hospital, by phone,
or by e-mail. Of these 70, 6 dropped out for personal rea-
sons, so 64 subjects were finally included in this study.
Subjects all gave voluntary informed consent prior to the
beginning of the study.
Inclusion criteria were adults over the age of 20 with
posterior neck pain graded more than 4 using the visual
analog scale (VAS) that had lasted more than 3 months.
Exclusion criteria were acute inflammation findings in
blood tests, limitation of C-ROM because of cervical spi-
nal fixation operations, inability to walk for more than an
hour because of knee problems, or if residing in a forest
for more than a week was a hardship for any reason in-
cluding the presence of underlying disease.
Screening tests included simple radiographs of the cer-
vical spine and both knee joints, routine blood tests, and
Therapeutic Effect of Forest Therapy on Chronic Neck Pain
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VAS of cervical neck pain. On the first day of the experi-
ment in the forest, 2 rehabilitation medicine physicians
evaluated VAS on that day, VAS over the previous week,
neck disability index (NDI), EuroQol 5D-3L VAS (EQ VAS)
and index (EQ index), McGill pain questionnaire (MPQ),
the number of trigger points in the posterior neck region
(TRPs), and C-ROM. All the same tests were performed
by the same physicians on the last day of the experiment.
The VAS was developed for evaluating factors that are
difficult to objectively assess; it is commonly used for
evaluating pain levels [15]. In general, patients are pre-
sented with a 10-cm horizontal line anchored by ‘no
pain’ on one end and ‘pain as bad as it could be’ on the
other end; subjects mark the point on the line that they
feel represents their pain level. The VAS score is deter-
mined by measuring length (cm) on the line between the
‘no pain’ anchor and the subjects’ mark. Authors defined
‘VAS on one day’ as the level of posterior neck pain on
that day and ‘VAS over the previous week’ as an average
pain level of the posterior neck region during the preced-
ing week.
The NDI is a questionnaire developed in 1991 for the
purpose of helping to understand how neck pain affects
one’s ability to manage everyday activities. It consists of
10 sections with 6 multiple choice questions per section
[16].
The EQ VAS and index were developed by the EuroQol
Group. They are standardized measurement tools that
assess an individual’s health status [17]. EQ VAS is evalu-
ated in a similar manner as is VAS. Subjects mark their
status on a vertical line anchored by 0 and 100 at either
end to indicate ‘Your own health state today.’ A score of 0
means ‘Worst imaginable health state’ and a score of 100
means ‘Best imaginable health state.’ The EQ index has
5 sections, which are mobility, self-care, usual activities,
pain/discomfort, and anxiety/depression, and each sec-
tion has 3 possible answers.
The MPQ is a self-reported measure of pain level. It is
composed of 78 words in 20 categories; for each category,
subjects choose the word that best represents their feel-
ing of pain. Scores are calculated by summing the values
associated with each word and a higher score means
more severe pain [18].
A TRP is defined as a hyperirritable spot and is diag-
nosed if a subject feels pain when weak pressure (less
than 4 kg/cm
2
) is applied with a pressure algometer [19].
In this study, the researchers examined bilateral cervical
paraspinal, upper trapezius, and infraspinatus muscles,
which are related to posterior neck pain, and counted the
number of TRPs in these 6 muscles.
The C-ROM was evaluated by summating measures of
cervical flexion, extension, right lateral bending, left lat-
eral bending, right rotation, and left rotation.
Sixty-four subjects (11 males, 53 females) were ran-
domly divided into a forest bathing alone (FBA) group
(n=32) and a forest bathing with exercise (FBE) group
(n=32). Both groups participated in a program consist-
ing of 2 hours of walking in the forest every morning
for 5 days. For 2 hours each afternoon, the FBE group
did additional stretching and strengthening exercises
targeting muscles in the cervical and shoulder regions.
This exercise program was developed and organized by
a committee composed of four physicians specializing
in rehabilitation medicine and three physical therapists
after a literature review. The exercise program consists
of a 10-minute warm-up followed by 30 minutes of main
Fig. 1. Flow chart showing the
schedule and plan of this study.
Screening
(7-10 days before
the program
was started)
The first day of
the program
The last day of
the program
Forest bathing alone for7days
Forest bathing with exercise for7days
Comparison
Boram Kang, et al.
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exercise and a 10-minute cool down. Subjects rest for 10
minutes and then repeat the exercise program, so the
total exercise time is 2 hours. The warm-up exercise is
composed of light stretching; not only the cervical and
shoulder regions but the whole body is included. In the
main exercise, exercise intensity is gradually increased
and stretching and strengthening exercises are focused
on the cervical and shoulder regions. Although the cool
down exercise is composed of only stretching, the inten-
sity is higher than that of the main exercise. In contrast
with the FBE group, the FBA group did not do the exer-
cise program in the afternoon and instead had free time
in the forest. After dinner, the FBE group did another 2
cycles of the same exercise program and the FBA group
again had free time in the forest (Fig. 1).
Pain levels pre-intervention and post-intervention were
compared between the FBA and FBE groups using the
Mann-Whitney U test. The Wilcoxon signed-rank test was
used to compare pre-intervention versus post-interven-
tion outcomes in each group. The p-value for significance
was set at 0.05.
RESULTS
There was no significant difference in age, sex, height,
or weight between the FBA and FBE groups. VAS on the
day of screening and the first day of the forest program
showed no significant difference between the two groups
(p=0.779 and p=0.767) (Table 1). Most subjects were un-
employed or students; only 5 subjects in the FBE group
and 4 subjects in the FBA group had jobs. Of the em-
ployed subjects in the FBE group, 2 were office clerks, one
Table 1. Subject characteristics
Variable Forest bathing alone (n=32) Forest bathing with exercise (n=32) p-value
a)
Age (yr) 50.0±14.93 54.8±9.78 0.828
Sex (male:female) 5:27 6:26 0.515
Height (cm) 160.1±6.20 160.7±6.81 0.669
Weight (kg) 58.4±10.17 59.9±9.45 0.985
VAS at screening 5.9±1.26 6.4±1.33 0.779
VAS on the first day 5.2±1.61 5.3±1.64 0.767
Values are presented as mean±standard deviation or number.
VAS, visual analog scale.
a)
p-values were calculated using the independent t-test (p<0.05, statistically significant).
Table 2. Difference between the two types of forest therapy program (n=64)
Forest bathing alone (n=32) Forest bathing with exercise (n=32) p-value
c)
VAS on one day
a)
–2.7±1.69 –2.9±1.93 0.559
VAS over the previous week
a)
–2.8±1.40 –3.1±1.77 0.485
NDI
a)
–15.1±8.45 –11.3±11.73 0.181
EQ VAS
b)
28.7±15.12 21.8±20.97 0.165
EQ index
b)
0.28±0.192 0.22±0.154 0.129
MPQ
a)
–13.5±10.75 –13.3±13.39 0.652
TRPs
a)
–1.0±1.49 –2.1±1.66 0.013*
C-ROM
b)
74.7±60.69 85.2±58.46 0.667
Values are presented as mean±standard deviation.
VAS, visual analog scale; NDI, neck disability index; EQ VAS, EuroQoL 5D-3L VAS; EQ index, EuroQol 5D-3L index;
MPQ, McGill pain questionnaire; TRPs, trigger points in the posterior neck region; C-ROM, cervical range of motion.
a)
Negative change indicates improvement.
b)
Positive change indicates improvement.
c)
p-values were calculated using the Mann-Whitney U test.
*p<0.05, statistically significant.
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was self-employed, one worked as a translator, and one
was a lecturer; in the FBA group, 2 were office clerks and
2 were self-employed.
Of all the pain assessment methods used to compare
the two groups post-intervention, only the number of
TRPs was significantly different; it was lower in the FBE
group than in the FBA group (p=0.013). The other scales
showed no significant differences between the two
groups (Table 2).
All evaluated scales (VAS on a particular day, VAS
over the previous week, NDI, EQ VAS and index, MPQ,
the number of TRPs, and C-ROM) showed significant
improvement after 7 days of the forest program in both
groups (Table 3).
DISCUSSION
When we analyzed VAS on one day, VAS over the pre-
vious week, MPQ, and NDI, which reflect intensity of
posterior neck pain, there were no significant differences
between individuals in the two types of forest program.
These results could be interpreted to mean that adding
an exercise program to forest bathing is not an effective
way to reduce posterior neck pain. EQ VAS and index,
which reflect general health status, also showed no sig-
nificant differences according to the type of forest pro-
gram.
As mentioned above, posterior neck pain results in
muscle spasms and decreased C-ROM in most cases
regardless of the primary cause of pain. Therefore, we
thought that evaluating the number of TRPs and C-ROM
could be helpful for verifying pain intensity in the poste-
rior neck region. C-ROM showed no significant difference
between the two groups, like all other scales mentioned
above. However, the number of TRPs was significantly
reduced in the FBE group compared with the FBA group,
which suggests that adding a stretching and strengthen-
ing exercise to forest bathing is more effective in reducing
the number of TRPs than forest bathing alone.
It is unclear why intensity of pain, health status, and
C-ROM were not significantly better in the FBE group in
spite of a significant reduction in the number of TRPs.
The authors’ opinions about this issue are as follows. 1)
The measurement method for detecting TRPs used in this
study was a test for ‘latent TRPs,’ which are spots where
pain is felt after applying weak pressure; these could be
Table 3. Scores of each group on the first and last days of the forest program
Forest bathing alone (n=32) Forest bathing with exercise (n=32)
The first day of
the program
The last day of
the program
p-value
c)
The first day of
the program
The last day of
the program
p-value
c)
VAS on one day
a)
5.2±1.61 2.5±1.58 <0.001* 5.3±1.64 2.4±1.24 <0.001*
VAS over the previous week
a)
5.7±1.55 2.9±1.45 <0.001* 5.8±1.52 2.7±1.48 <0.001*
NDI
a)
33.2±10.82 18.1±8.72 <0.001* 30.0±10.36 18.6±9.84 <0.001*
EQ VAS
b)
47.3±16.89 75.9±14.74 <0.001* 50.8±16.92 72.6±15.72 <0.001*
EQ index
b)
0.59±0.212 0.87±0.071 <0.001* 0.64±0.176 0.86±0.079 <0.001*
MPQ
a)
26.4±13.48 12.9±10.81 <0.001* 22.7±11.45 9.4±8.02 <0.001*
TRPs
a)
4.5±1.46 3.5±1.68 0.001* 4.3±1.49 2.3±1.32 <0.001*
C-ROM
b)
261.6±68.40 336.3±71.58 <0.001* 254.3±73.09 339.4±84.19 <0.001*
Values are presented as mean±standard deviation.
VAS, visual analog scale; NDI, neck disability index; EQ VAS, EuroQol 5D-3L VAS; EQ index, EuroQol 5D-3L index; MPQ, McGill pain questionnaire;
TRPs, trigger points in the posterior neck region; C-ROM, cervical range of motion.
a)
Lower value indicates better status.
b)
Higher value indicates better status.
c)
p-values were calculated using the Wilcoxon signed-rank test.
*p<0.05, statistically significant.
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different from ‘active TRPs,’ which reflect pain subjects
feel in the absence of any external pressure. Therefore,
it is possible that, although the number of ‘latent TRPs’
was significantly reduced in the FBE group compared to
the FBA group, the number of ‘active TRPs’ was not. 2)
Because on average more than 2 TRPs still remained in
patients in the FBE group, intensity of pain, health sta-
tus, and C-ROM might not be affected. In addition, in
this study, identifying the pain threshold of the remain-
ing TRPs was impossible because a TRP was diagnosed
if subjects felt pain less than 4 kg/cm
2
but other pres-
sures were not tested. 3) TRPs do not necessarily reflect
the main source of pain. Not only muscle but also bone,
ligament, disc, nerve, etc. could be the focus of posterior
neck pain. Likewise, C-ROM may remain limited because
muscle pain is not the only cause of muscle spasms and
limitations in ROM.
When comparing outcomes pre-intervention versus
post-intervention, all scales showed significant improve-
ment in both groups. This result suggests that forest bath-
ing is effective in relieving pain and improving the health
status of subjects with posterior neck pain. However, this
conclusion has limitations because it is impossible to ex-
clude the effect of simply resting on pain relief and health
status improvement given the design of this study.
This study has several limitations. First, the duration
of forest bathing was one week and the duration of the
program was 5 days, which are short periods of time.
Although the authors set the duration based on the dura-
tion of previous studies, most of which were 3 to 7 days,
such short durations might be a cause of the insignificant
effect of the stretching and exercise program. However,
this short duration could be meaningful in respect to
real life, in which many people spend from 2 or 3 days to
about 7 days forest bathing during their weekends or va-
cations. In a follow-up study, we plan to compare the ef-
fect of the exercise program in longer-term forest bathing.
Second, the ages of the subject did not show a normal
distribution; specific ages were overrepresented. Because
subjects had to make time to participate in a week-long
study, students in their 20s and adults older than 50 made
up the majority of the participants. As the effect of rest-
ing on pain relief and health status improvement could
be limited to some degree because most of these subjects
had no jobs, the result would be more meaningful if the
next study includes patients with normally distributed
ages and more patients who are employed. Third, as
mentioned above, the effect of resting was not controlled.
To solve this problem, in the next study, the FBA group
must be compared with a group of participants who take
a rest period in the city of the same duration.
In conclusion, when short-term forest bathing (less
than 7 days) was used to treat patients with chronic pos-
terior neck pain for the purposes of pain relief and health
status improvement, FBE is more effective in the reduc-
tion of the number of TRPs than FBA. However, all other
scales we evaluated showed no statistically significant
difference between the two protocols.
CONFLICT OF INTEREST
No potential conflict of interest relevant to this article
was reported.
ACKNOWLEDGMENTS
This research is supported by Ministry of Culture, Sports
and Tourism (MCST) and Korea Creative Content Agency
(KOCCA) in the Culture Technology (CT) Research & De-
velopment Program 2015 and Korea Forest Service.
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