International Journal of
Environmental Research
and Public Health
Article
Seasonal Differences in Physiological Responses to Walking in
Urban Parks
Chorong Song 1 , Harumi Ikei 2 and Yoshifumi Miyazaki 2,*
1 Department of Forest Science, Kongju National University, 54 Daehak-ro, Yesan-eup,
Yesan-gun 32439, Chungcheongnam-do, Korea
2 Center for Environment, Health and Field Sciences, Chiba University, 6-2-1 Kashiwa-no-ha,
Kashiwa 277-0882, Chiba, Japan
* Correspondence: ymiyazaki@faculty.chiba-u.jp; Tel.: +81-4-7137-8184; Fax: +81-4-7137-8008
Citation: Song, C.; Ikei, H.; Miyazaki,
Y. Seasonal Differences in
Physiological Responses to Walking
in Urban Parks. Int. J. Environ. Res.
Public Health 2022, 19, 12154.
https://doi.org/10.3390/
ijerph191912154
Academic Editor: Paul B.
Tchounwou
Received: 5 August 2022
Accepted: 22 September 2022
Published: 26 September 2022
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Abstract: The aim of the current study was to assess seasonal differences in physiological responses
to walking in urban parks. In total, 51 Japanese male university students participated in this research.
During each season, the participants walked for 15 min in an urban park and a city area, which was
used as the control site. Heart-rate variability and heart rate were used as physiological indicators.
The mean values of each indicator in a comparison between walking in an urban park and a city area
were compared according to each season. In addition, to show the physiological effect of walking
in an urban park, differences (between walking in an urban park and walking in a city area) were
calculated. Then, differences according to each season were compared. The results showed that the
participants had increased parasympathetic nervous system activity in all seasons except summer.
Moreover, they had decreased sympathetic nervous system activity in spring and fall and decreased
heart rate in all seasons. Compared with walking in urban parks in summer, walking in urban parks
in spring, fall, and winter had a greater relaxation effect on parasympathetic and sympathetic nervous
system activities; hence, the physiological effects of walking in urban parks vary based on season.
Keywords: forest therapy; heart rate; heart-rate variability; physiological relaxation; preventive
medicine; urban green space
1. Introduction
In modern times, people commonly spend their daily lives sitting indoors [1], and the
number of populations with insufficient physical activity has increased [2]. This type of
lifestyle has caused significant health issues. If this problem is not immediately resolved,
people will be at high risk of metabolic diseases, and they can develop different chronic
diseases, such as diabetes and cardiovascular conditions [3–5].
Since the importance of physical activity is emphasized [6], the role of urban green
spaces in promoting the health and well-being of humans has received increasing attention.
Urban green spaces are the most accessible natural environments for people in modern
times. Moreover, they have important social, physical, and mental benefits that enrich the
lives of urban residents [7–11].
Previous studies have been conducted to assess the advantages of the natural environ-
ment. Walking in urban forests has a restorative effect countering psychological stressors
or mental fatigue [12–14] and can improve mood and cognitive function [15,16]. Epidemio-
logical research has revealed a positive association between exposure to urban green spaces
and the perceived general health and longevity of residents [17–19]. Moreover, physical
activities, such as brief walking in an urban park, have physiological relaxation effects
and psychological advantages. For example, they can improve mood states and relieve
anxiety [20–22]. Recent studies have evaluated the increasing value of urban green spaces
for human benefits from different perspectives, such as socioeconomic welfare [23,24] and
Int. J. Environ. Res. Public Health 2022, 19, 12154. https://doi.org/10.3390/ijerph191912154
https://www.mdpi.com/journal/ijerph
Int. J. Environ. Res. Public Health 2022, 19, 12154
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ecosystem services [25]. However, research about the effect of direct use among humans,
such as spending time in urban green spaces, may be insufficient.
Previous reports, which used similar experimental design and locations, partly exam-
ined the effects of walking in urban parks in spring [20], fall [21], and winter [22]. These
studies showed that walking in urban parks has physiological and psychological benefits,
and that the effects differed according to season. However, there is no study comparing
differences in the effects of walking in urbbaondyp’asrrkessapcocnosred.inIng wtoinsetears,otnh.e body’s stress re-
The thermal environment is expected to change along with seasonal changes, and
it has a significant impact on the human body’s response. In winter, the body’s stress
response caused by the cold can be reduced by wearing clothes, but in summer, the outdoor
heat cannot be controlled. Thus, the relaxation effect of walking in the urban park is
expected to be lower in summer than in other seasons. Therefore, the aim of this study
is to assess seasonal differences in physiological responses to walking in urban parks. A
new experiment was performed in the summer, and data analysis was conducted using the
previously reported spring [20], fall [21], and winter [22] data.
2. Materials and Methods
2.1. Experimental Sites
The study was conducted in Kashiwa-no-ha Park in Kashiwa City, Chiba Prefecture,
Japan. The site has a large pond at the center, and several hardwood trees are planted, such
as maple, tulip, cherry, and chestnut. Thus, people can feel seasonal changes (Figure 1).
The participants walked around its large pond. A city area around the urban park was
selected as the control site. It was surrounded by housing complexes and commercial facilities
(Figure 2). The experiments were commonly performed during sunny days. Table 1 shows
the temperature, relative humidity, and intensity of illumination of the two experimental sites.
Spring
Summer
Fall
Winter
Figure 1. Experimental scene in the urban park. The top left photo (spring), bottom left photo (fall),
and bottom right photo (winter) are reprinted from Song et al. (2014) [20], Song et al. (2015) [21], and
Song et al. (2013) [22], respectively.
Int. J. Environ. Res. Public Health 2022, 19, 12154
Spring
Fall
3 of 9
Summer
Winter
Experimental day
Experimental site
Temperature (◦C)
Relative humidity (%)
Illumination (lx)
Figure 2. Experimental scene in the city area. The top left photo (spring), bottom left photo (fall), and
bottom right photo (winter) are reprinted from Song et al. (2014) [20], Song et al. (2015) [21], and
Song et al. (2013) [22], respectively.
Table 1. Details of the experimental site.
Spring
Summer
15 May 2013
16 May 2013
17 May 2013
30 July 2014
31 July 2014
UP
CA
UP
CA
27.0
24.7
31.3
35.6
37.3
39.2
53.8
40.3
80,730
4990
3550
62,890
UP, urban park; CA, city area.
Fall
07 October 2014
15 October 2014
16 October 2014
UP
CA
18.0
19.2
71.5
64.7
24,230
38,870
Winter
21 November 2012
23 November 2012
24 November 2012
UP
CA
13.8
14.0
50.9
52.1
7930
8430
2.2. Participants
This research was conducted in accordance with the guidelines of the Declaration of
Helsinki, and the protocol was approved by the Ethics Committees of the Center for Environ-
ment, Health and Field Sciences, Chiba University, Japan (project identification no. 5).
Twelve Japanese male university students participated in the summer experiment.
They were recruited through snowball sampling. The inclusion criteria were healthy
male university and graduate students age–d 20–29 years, and the exclusion criterion was
diagnosis of respiratory diseases (chronic rhinitis, asthma, etc.). For other diseases, a
self-reporting system was adopted, and the experimenter conducted observation when
explaining the ethics review before the experiment. The participants for experiments in
other seasons were recruited using the same sampling method and inclusion and exclusion
criteria. They were informed about the aims and procedures of the study prior to conducting
the experiment. Moreover, informed consent was obtained. Consumption of alcohol,
tobacco, and caffeine was prohibited during the study period.
Seasonal difference was analyzed using data obtained from 51 people (spring: n = 12,
summer: n = 12, fall: n = 20, and winter: n = 7). The mean ± standard deviation of
Int. J. Environ. Res. Public Health 2022, 19, 12154
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age, height, and weight were 22.2 ± 2.0 years, 172.1 ± 5.1 cm, and 63.4 ± 8.0 kg, re-
spectively. In detail, the mean ± standard deviation of age, height, and weight were
21.1 ± 1.7 years, 173.5 ± 5.4 cm, and 62.7 ± 6.9 kg in spring; 22.3 ± 1.4 years, 170.4 ± 4.5 cm,
and 64.9 ± 10.3 kg in summer; 22.3 ± 1.2 years, 171.1 ± 4.7 cm, and 62.3 ± 7.0 kg in fall;
and 23.6 ± 4.0 years, 176.0 ± 5.1 cm, and 65.5 ± 8.7 kg in winter.
2.3. Experimental Procedure
Each subject walked in the urban park or city area for 15 min. A within-subject
experimental design was used. Two participants were paired to eliminate the effect of
the order of sites walked. One participant walked first in the urban park and then in the
city area. Meanwhile, the other participant walked first in the city area and then in the
urban park. After walking, they returned to the waiting room and completed several
questionnaires. They rested for approximately 20 min and repeated the experiment in the
opposite areas. The walking distance between the urban park and city area was the same,
and the participants were instructed to walk slowly and at the same speed. There was
no difference in the physiological indices before the start of each walk between the two
environments. In addition, there were no significant differences with respect to the average
walking speed of the participants between the two environments.
2.4. Physiological Measurements
Heart rate and heart-rate variability (HRV) were used as physiological indicators.
HRV is effective in assessing the interplay between the sympathetic and parasympathetic
nervous activities [26].
The periods between consecutive R waves (R–R intervals) assessed using a portable
electrocardiogram (Activtracer AC-301A; GMS, Tokyo, Japan) were analyzed to obtain
HRV and heart rate. The power levels of the low-frequency (LF, 0.04–0.15 Hz) and high-
frequency (HF, 0.15–0.40 Hz) components of the HRV were calculated using the maximum
entropy method with MemCalc/Win (GMS) [27]. To normalize the HRV parameters across
participants, natural logarithmic-transformed values were used in the analysis [28]. The
HF component of the HRV reflects the parasympathetic nervous activity and the LF/HF
reflects the sympathetic nervous activity [29].
2.5. Data Analysis
All statistical analyses were performed using the Statistical Package for the Social
Sciences software, version 20.0 (IBM Corporation, Armonk, NY, USA). In addition to the
new summer experiments, data from three previous experiments were analyzed. The
average heart rates, ln(HF) and ln(LF/HF), during the 15 min walking period in the two
sites were used in the analysis. In each season, the values between walking in an urban
park and a city area were compared using the paired t-test.
To show the effect of walking in an urban park, differences (between walking in an
urban park and walking in a city area) were calculated. Then, differences according to
season were compared using one-way analysis of variance and the post-hoc test (Tukey
HSD test). A p value of <0.05 was considered statistically significant.
3. Results
In summer, heart rates were significantly lower while walking in an urban park than
those while walking on a city street (92.3 ± 2.3 vs. 96.1 ± 2.7 bpm, p < 0.01). There were
no statistically significant differences with respect to ln(HF) (3.5 ± 0.3 vs. 3.3 ± 0.3 lnms2,
p > 0.05) and ln(LF/HF) (1.90 ± 0.14 vs. 1.89 ± 0.13, p > 0.05) between walking in an urban
park and on a city street.
Figure 3 shows the differences in the changes in ln(HF), which is an indicator of
parasympathetic nervous system activity, between walking in an urban park and on a city
street according to the four seasons.
Int. J. Environ. Res. Public Health 2022, 19, 12154
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1.5
*
1.0
†
0.5
†
0.0
**
*
†
†
†
†
−-0.5
−0
Sp春ri季ng
春季
Su夏m季mer
秋Fa季ll
W冬in季ter
夏季
秋季
冬季
Figure 3. Differences in the changes in ln(HF) between walking in an urban park and a city area
according to the four seasons. n = 51 (spring: n = 12, summer: n = 12, fall: n = 20, and winter: n = 7),
meanm±esatnan±dsatradnddeavrdiadtieovni,a†ti:on, †: p < 0.05 using the paired t-test (urban park vs. city area), *: p < 0.05,
meana±nsdta*n*:dpar<d 0d.e0v1iautsioinng, †o: ne-way analysis of variance with the post-hoc test (four seasons).
The ln(HF) values during walking in an urban park were significantly higher compared
to the city
difference
walking
in ln(HF)
in
in
spring, fall, and
summer (3.51 ±
w0.2in9tvers.[32–.06–52±2–].0H.3o4wlnemves2r,,
there was no significant
p > 0.05). Based on these
results, there were significant differences in seasonal changes (F(3,47) = 5.397, p < 0.01).
Differences in ln(HF) by walking in an urban park were significantly higher in spring, fall,
spprriinnaggn,,dfafawlll,li,annatendrdwcowinmitneprtaecrroecmdopwmairptehadrseuwdmitwhmisetuhrm(ssmupmerirnm(gse:pr0ri.(n6sg0p:r±0in.60g0.:1±80.0v6.s01.8±svu0sm.1sm8umevrsm:. −esru0:m.−104m.1±e4r±:0.−103.,1p4 <± 0.05;
fall: 0.51 ± 0.08 vs. summer, p < 0.05; and winter: 0.94 ± 0.46 vs. summer, p < 0.01).
Figure 4 shows the differences in the changes in ln(LF/HF), which is an indicator of
sympathetic nervous system activity, between walking in an urban park and in a city area
according to the four seasons. The ln(LF/HF) during walking in an urban park was signifi-
cantly lower compared to walking in the city area in spring and fall [20,21]. However, there
was no significant difference with respect to ln(LF/HF) between participants who walked in
an urban area and those who walked in a city area in summer (1.91 ± 0.15 vs. 1.74 ± 0.20,
p > 0.05) and winter [22]. Therefore, a significant difference was observed in seasonal
changes (F(3,47) = 5.979, p < 0.01). Differences in ln(LF/HF) by walking in an urban park
were significantly lower in a city area in spring, fall, and winter compared with summer
ssuummmm(psep<errr(0is(n.sp0gpr1:iwr;nia−nginn:g0td−:e.04r−w.:204−2.i±40n±.2t3e008±r..11:±011−.01v.v102ss0..v3.sv8suss.m±u.summ0mme.2rm0:e0rev.:r1s:70.0.±s1.u1707m.1±±2m,00e..1r1<,220p,,.0<p1<;0<0f.a0.00l5l.10:).;−1f0;a.f3lal9:l±l−:00−..30099.v±3s90. .s±0u9m0v.m0s.9esrvu, sm. msuemr,mer,
** winter: −0.38 ± 0.20 vs.
0.4
0.0
−-0.4
−0
−-0.8
−0
†
Sp春ri季n†g
**
Su夏m季mer
†
秋Fa*季ll †
W冬in季ter
Figure 4. Differences 春in t季he changes in l夏n(L季F/HF) walking秋in 季an urban park a冬nd季in a city area
according to the four seasons. n = 51 (spring: n = 12, summer: n = 12, fall: n = 20, and winter: n = 7);
mean ± standard deviation, †: p < 0.05 using the paired t-test (urban park vs. city area); *: p < 0.05;
and **: p < 0.01 using one-way analysis of variance with the post-hoc test (four seasons).
Int. J. Environ. Res. Public Health 2022, 19, 12154
mean ± standard deviation, †:
6 of 9
Figure 5 shows the differences in the changes in heart rate between walking in an
urban park and in a city area according to the four seasons. The heart rate during walking
in an urban park was significantly lower compared to walking in the city area in all
seasons –[20–22] including summer (92.1 ± 3.2 vs. 95.0 ± 3.5 bpm, p < 0.05). However, there
were no significant differences in seasonal changes (F(3,47) = 0.082, p > 0.05).
0.0
−-2.0
−-4.0
−-6.0
†
Sp春ri季ng
†
Su夏m季mer
†
秋Fa季ll
†
W冬in季ter
Figure 5. Differences in the changes in heart rate between walking in an urban park and walking
in a city area according to the four seasons. n = 51 (spring: n = 12, summer: n = 12, fall: n = 20, and
winter: nn==77););mmeeaann±±stsatnadnadradrddedveivaitaitoino,n†, :†: p < 0.05 using the paired t-test (urban park vs. city area).
4. Discussion
In summer, the heart rate decreased significantly. However, there was no significant
change in the parasympathetic and sympathetic nervous system activities. This was not in
accordance with the results in other seasons [20,21]. The thermal environment is thought to
have a highly influential effect. In winter, the body’s stress response caused by the cold
tchaonubgehrtetdouhcaevdebayhwigehalryiningflculoetnhteiasl, ebfufet cint. sInumwmineter,r,ththeeobuotddoyo’srshtreeastscraensnpootnbsee ccoauntsreodllbedy.
Thus, the relaxation effect may have been lower in summer than in other seasons.
The physiological responses to walking in urban parks according to the four seasons
are as follows: the parasympathetic nervous system activity of the participants increased in
all seasons except summer. Moreover, the participants had decreased sympathetic nervous
system activity in spring and fall and decreased heart rate in all seasons.
Our results are almost consistent with those of previous studies that assessed the phys-
iological effects of spending time in the forest environment [30,31]. These studies revealed
that a simple walk or a rest in the forest can promote physiological relaxation as represented
by increased parasympathetic nervous system activity and decreased sympathetic nervous
system activity and heart rate. The current study had a similar result; that is, the effects of
walking in urban green areas are similar to those of walking in forest areas.
In addition, walking in spring, fall, and winter had a greater physiological relaxation
effect than walking in summer. Walking in spring and fall had the highest physiological
relaxation effect. If people can well maintain warmth even in winter, walking can have
physiological benefits.
Only few studies have assessed the effects of walking according to seasonal differences
in urban green spaces. Cohen et al. [32] showed the climatic conditions between summer
and winter in various urban parks with different vegetation coverage and their impacts
on human thermal sensation. The results showed that an urban park with a dense canopy
of trees has a maximum cooling effect during summer. However, it may have a negative
effect on human thermal comfort in winter. By contrast, because it is hot during summer
and cold during winter in lawn parks, the establishment of treed open spaces is important
as they are most effective in mitigating heat. Yang et al. [33] showed the impacts of the
composition and configuration of urban green spaces on urban thermal environment in all
four seasons. However, these studies did not examine their direct effect on humans.
Int. J. Environ. Res. Public Health 2022, 19, 12154
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This research included male participants aged 20–29 years with a limited sample
size and provided novel evidence on seasonal differences in physiological responses to
walking in urban parks. The results provide helpful information on the use of parks in
urban planning.
A recent study reported that middle-aged and older adults walking in an urban park
exhibited lower heart rates and blood pressure [34]. These results suggest that walking
in an urban park may be beneficial not only for young men but also for older people. To
generalize our findings, studies with female participants, different age groups, and larger
sample sizes should be conducted.
There is evidence supporting the beneficial health effects (e.g., improved HRV and de-
creased anxiety) of repeated moderate-intensity walking session in these environments [35].
In future studies, the effects of long-term and repetitive walking in urban parks should be
reviewed in various ways, and attention should also be paid to the advantages of various
activities in green spaces.
In addition, factors affecting seasonal changes, which have caused differences in
physiological responses, must be validated.
5. Conclusions
The present study showed seasonal differences in physiological responses to walking
in urban parks; that is, the participants had increased parasympathetic nervous system
activity in all seasons except summer. Moreover, they had decreased sympathetic nervous
system activity in spring and fall, during which people experienced a positive feeling
while walking. The heart rate of the participants decreased in all seasons. We conclude
that walking in spring, fall, and winter had a greater physiological relaxation effect than
walking in summer.
Author Contributions: Conceptualization, C.S. and Y.M.; methodology, C.S. and Y.M.; formal analy-
sis, C.S.; investigation, C.S., H.I. and Y.M.; data curation, C.S., H.I. and Y.M.; writing—original draft
preparation, C.S.; writing—review and editing, C.S., H.I. and Y.M.; visualization, C.S.; supervision,
Y.M.; project administration, Y.M.; funding acquisition, Y.M. All authors have read and agreed to the
published version of the manuscript.
Funding: This research was funded by Chiba University.
Institutional Review Board Statement: The study was conducted in accordance with the Declaration
of Helsinki and the protocol was approved by the Ethics Committee of the Center for Environment,
Health, and Field Sciences, Chiba University, Japan (project identification code number: 5).
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.
Data Availability Statement: The data that support the finding of this study are available from the
corresponding author upon reasonable request.
Acknowledgments: This study was performed with the permission of the Corporation for Urban
Enhancement of Chiba Prefecture, Japan. We also appreciate their co-operation. We are grateful to
Miho Igarashi for valuable contributions in the data-collection phase of this study.
Conflicts of Interest: The authors declare no conflict of interest.
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