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The eect of smartphone usage time on posture
and respiratory function
Sang In Jung, MS, PT1), na Kyung Lee, PhD, PT1), Kyung Woo Kang, PhD, PT1),
Kyoung KIm, PhD, PT1), Do youn Lee, MSc, PT1)*
1) Department of Physical Therapy, College of Rehabilitation Science, Daegu Universit y: 15 Jilyang,
Gyeongsan-si, Kyeongbuk 712-714, Republic of Korea
Abstract. [Pur pose] The aim of this study was to evaluate the changes in posture and respirator y functions
depending on the duration of smartphone usage. [Subjects and Methods] Participants were randomly allocated to
2 groups: group 1 (subjects who used smartphones for <4 hours/day, n=25) and group 2 (subjects who used smart-
phones for >4 hours/day, n=25). The craniovertebral angles of all participants were measured and scapular indices
were calculated to assess the change in posture and forced vital capacity, forced expiratory volume in 1 second, the
ratio of forced expiratory volume in 1 second to forced vital capacity, and peak expirator y ow were measured to
assess changes in respiratory function. [Results] There were signicant differences in the craniovertebral angle,
scapular index, and peak expiratory ow depending on the duration of smartphone usage. [Conclusion] The result of
this study showed that prolonged use of smart phones could negatively affect both, posture and respiratory function.
Key words: Smartphone, Posture, Respiratory function
(This article was submitted Sep. 24, 2015, and was accepted Oct. 14, 2015)
INTRODUCTION
In the past few years, the number of smartphone users have progressively increased worldwide1). With the growing
use of smartphones, concerns have also increased about musculoskeletal problems associated with the prolonged use of
smartphones. Recent investigations have shown that smartphone users tend to report pain in the neck, shoulder, and thumb,
and the severity of the symptoms as the total time spent using the smartphone increases2). Prolonged smart phone usage
causes faulty posture such as forward neck posture, slouched posture, or rounded shoulders3). Sustained forward neck posture
can cause injury to the structure of the cervical and lumbar spine, as well as ligaments4, 5). These structural problems caused
by faulty posture can also lead to respiratory dysfunction6). Perry et al. investigated the possibility correlation between
dysfunctional breathing and musculoskeletal pain patterns. Their result showed that 83% of patients with neck pain (caused
by faulty posture) experienced a changed breathing pattern. This study indicated that there was a relationship between neck
pain and respiration7). The adverse effects of prolonged sitting and a sedentary lifestyle on our health are well known, and
similarly, we should understand the effect of prolonged smartphone usage on our posture and respiratory function. Therefore,
our study focused on the change in the subjects body posture and respiratory function caused by using smartphones for
prolonged durations. The aim of this study was to evaluate the changes in the posture and respiratory functions depending on
the duration of smartphone usage.
SUBJECTS AND METHODS
Fifty healthy volunteers were recruited from Daegu University, South Korea. The subject characteristics (mean ± SD)
were: 21 ± 2.41 years old; 168 ± 8.15 cm in height; 65 ± 14.41 kg in body weight. The subjects were divided in to 2 groups
J. Phys. Ther. Sci. 28: 186–189, 2016
*Corresponding author. Do Youn Lee (E-mail: tr iptoyoun@gmail.com)
©2016 The Society of Physical Therapy Science. Published by IPEC Inc.
This is an open-access ar ticle distributed under the terms of the Creative Com mons Attribution Non-Commercial No Der ivatives (by-nc-nd)
License <http://creativecom mons.org /licenses/ by-nc-nd/3.0/>.
Original Article
The Journal of Physical Therapy Science The Journal of Physical Therapy Science
187
according to the duration of smartphone usage reported by each individual: group 1 for those that used smartphones less than
4 hours per day (3.0 ± 1.0 hours), and group 2 for those that used smartphones for more than 4 hours each day (5.5 ± 1.0
hours).
Subjects were excluded if they met any of the following conditions: had experienced cervical fracture or trauma, bone
cancer, neurological motion disorders, restrictions in lung function, or other neurologic, orthopedic, or unstable cardiac con-
ditions; were smokers or smoke-free within 5 years; or had undergone thoracic or abdominal surgery. Informed consent was
voluntarily obtained from all the subjects prior to participation in the study, and this study was approved by the Institutional
Review Board of Daegu University.
To determine the subjects’ posture and lung function, we examined craniovertebral angle (CVA), scapular index and
respiratory function. Forward head posture (FHP) was assessed by using CVA. A lower CVA indicates greater FHP. CVA
showed good retest reliability in previous studies (intra-class correlation coefcients ranged from 0.88 to 0.98)8).
CVA was assessed by using a digital, lateral-view photograph of the subjects in their usual standing posture. A photograph
was taken laterally by using a digital camera (AlpaNEX-6; Sonny, China). The CVA was calculated by using Adobe Photo-
shop CS6. To minimize image distortion, the assessor placed a circular spirit level at the base of the camera to ensure that the
camera was positioned perpendiculary to the horizontal. The tragus of the subject’s ear was marked, and the seventh cervical
vertebra was found and marked by nding its bony landmark. This was done by asking the subject to ex and extend her
head 3 times, and then nding the seventh spinous process of the vertebra. The angle of FHP was calculated between the line
connecting the tragus of ear to seventh cervical vertebra and the horizontal plane9).
To assess for rounded shoulders, subjects were asked to stand normally with their hands hanging beside the body. The
coracoid process, sternal notch, posterior edge of the acromion process and the adjacent thoracic vertebral spine were then
palpated and marked. The distance between the coracoid process and sternal notch, and the distance between the posterior
edge of acromion process and the adjacent thoracic vertebral spine were measured by using tape. The scapular index was
calculated by using the following formula10, 11) (Fig. 1).
Test of respiratory function were performed by using a spirometer (Cardiotouch 3000. BIONET). The spirometer calcu-
lated and recorded the following measurements: forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1),
ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC), and peak expiratory ow (PEF). Each
subject was seated and asked to look straight ahead, while the mouthpiece of the spirometer was inserted into their mouth
and a nose clip was xed on their nose. The same assessor performed measurements throughout the entire experiment and
the most physiological respiratory function test results of three trials was recorded.
Statistical analysis was performed by using Statistical Package for Social Sciences (SPSS) version 18.0 (SPSS Inc.,
Chicago, USA). Data were analyzed by using the independent t-test to examine for differences in results between the 2
groups. Statistical signicance was dened as p < 0.05.
RESU LT S
A total of 50 subjects participated in the study, with 25 subjects in each group. The general characteristics of the subjects
were not signicantly different between the groups (p > 0.05). The observational data regarding CVA, scapular index, and
respiratory function tests of both groups is summarized in Table 1. Signicant differences were noted for CVA, scapular
index, and PEF of the 2 groups (p < 0.05).
DISCUSSION
Our study measured CVA and scapular index as parameters to demonstrate the effect of prolonged smartphone use on
change in posture. We also measured FVC, FEV1, FEV1/FVC and PEF as parameters to demonstrate the change in respira-
tory function cause by prolonged smartphone use. The results of this study show signicant differences in CVA, scapular
index and PEF. As shown in Table 1, subjects who used smartphones for prolonged durations tended to have poorer FHP
and rounded shoulders compared with the subjects who spent less time on smartphones. It also shows that people who used
smartphones for prolonged durations had partly impaired respiratory function.
FHP is one of the most common cervical abnormalities that predisposes individuals to pathological conditions, such as
headache, neck pain, temporomandibular disorders, vertebral body disorders, alterations in the length and strength of soft-
tissue, and scapula and shoulder dyskinesia12). Many studies proved that prolonged computer users tended to have a higher
ratio of FHP13–15). If people concentrate on watching the relatively small screen, they tend to bend their neck more to look at
the screen. This may be the reason for the development of more severe problems16).
As stated earlier, a lower CVA indicates greater FHP. In our study, subjects who use smartphone more than 4 hours per
day had lower CVAs. This result is consistent with the results from a recent study conducted by Kim et al. who showed
that the increase in both exion angles of the cervical and lumbar spine were signicantly higher in the group of prolonged
smartphone users (300 s) compared with the group of smartphone users that used the device for a short time (3 s)16). Another
study showed that many smartphone users had neck pain due to increased cervical angles17).
A lower scapular index indicates a higher degree of rounded shoulders. In our study, subjects who used smartphones more
J. Phys. Ther. Sci. Vol. 28, No. 1, 2016
188
than 4 hours per day, had lower scapular index. Many previous studies established that many sedentary workers tended to
have a rounded shoulder posture. In our study, the use of smartphones, as well as prolonged sitting caused the typical rounded
shoulder18). The other study showed that rounded shoulders is strongly associated with FHP19). Fernandez and colleague
reported that neck musculoskeletal disorder (such as altered cervical posture) is related to thoracic kyphosis and rounded
shoulder posture. Their hypothesis was that irregular lower trapezius condition and serratus anterior positions by abnormal
scapular tilt can lead to rounded shoulder posture5, 19).
In respiratory function, Only PEF showed signicant difference between the two groups. However, other variables (FVC,
FEV1, FEV1/FVC) also showed lower values like PEF in subjects using smartphone for prolonged duration. There are recent
researches about the correlation between posture and respiratory function. Baghery et al. reported that respiratory function in
slumped sitting is signicantly lower than in other postures such as normal sitting or standing20). Similarly, kyphotic posture
caused by using a smartphone for a long time can impair respiratory function.
The result of this study showed that using a smartphone for a prolonged duration could negatively effect both posture and
respiratory function. These results may be used to promote awareness about smartphone usage. For health considerations, we
need to pay attention to the duration of usage, as well as posture while using smartphones. This study has some limitations.
The number of subjects was relatively small and we did not investigate the statistical relationship between posture and
respiratory function. Another limitation is that we could not determine possible solutions to these problems. Therefore, future
studies should further extend on this study in order to evaluate the missing insights and determine possible solutions to the
problems caused by prolonged smartphone usage.
REFERENCES
1) Lee S, Kang H, Shin G: Head exion angle while using a smartphone. Ergonomics, 2015, 58: 220–226. [Medl i ne]
[CrossRef]
2) Berolo S, Wells RP, Amick BC 3rd: Musculoskeletal symptoms among mobile hand-held device users and their rela-
tionship to device use: a preliminary study in a Canadian university population. Appl Ergon, 2011, 42: 371–378. [Med-
li ne] [CrossRef]
3) Janwantanakul P, Sitthipornvorakul E, Paksaichol A: Risk factors for the onset of nonspecic low back pain in ofce
workers: a systematic review of prospective cohort studies. J Manipulative Physiol Ther, 2012, 35: 568–577. [Me dline]
[CrossRef]
4) Bonney RA, Corlett EN: Head posture and loading of the cervical spine. Appl Ergon, 2002, 33: 415–417. [Medl ine]
[CrossRef]
5) Fernández-de-las-Peñas C, Alonso-Blanco C, Cuadrado ML, et al.: Forward head posture and neck mobility in chronic
Fig. 1. The resting position of the scapula was determined by measuring the
distance from the midpoint of the sternal notch (SN) to the medial
aspect of the coracoid process (CP) (the leng th of the chest side) and
the horizontal distance from the posterolateral angle of the acromion
(PLA) to the thoracic spine (TS) (the length of the back side).
Tab le 1. Forward head posture ( FHP), round shoulder, and respirator y function of the 2 groups
Group 1 (n = 25) Group 2 (n = 25)
Forward head posture CVA (°) 54.5 (± 4.2) 53.0 (± 6.3)*
Round shoulder Scapular index 67.5 (± 4.2) 65.5 (± 6.5)*
Respiratory function test FVC (l) 3.3 (± 0.9) 2.8 (± 0.9)
FEV1 (l) 3.0 (± 0.8) 2.5 (± 0.8)
FEV1/FVC (%) 91.9 (± 9.9) 91.1 (± 8.6)
PEF (l/sec) 6.2 (± 2.3) 4.3 (± 1.5)*
Values are expressed as mean (± standard deviation)
FHP is represented by caraniovertebral angle (CVA), greater CVA values indicatess a lower FHP
*signicant difference between the 2 groups (p < 0.05)
189
tension-type headache: a blinded, controlled study. Cephalalgia, 2006, 26: 314–319. [Medl i ne] [CrossRef]
6) Kapreli E, Vourazanis E, Billis E, et al.: Respiratory dysfunction in chronic neck pain patients. A pilot study. Cepha-
lalgia, 2009, 29: 701–710. [Medli ne] [CrossRef]
7) Perri MA, Halford E: Pain and faulty breathing: a pilot study. J Bodyw Mov Ther, 2004, 8: 297–306. [CrossRef]
8) Raine S, Twomey LT: Head and shoulder posture variations in 160 asymptomatic women and men. Arch Phys Med
Rehabil, 1997, 78: 1215–1223. [Me dli ne] [CrossRef]
9) Quek J, Pua YH, Clark RA, et al.: Effects of thoracic kyphosis and forward head posture on cervical range of motion
in older adults. Man Ther, 2013, 18: 65–71. [Med line] [CrossRef]
10) Ramezanzade H, Arabnarmi B: Relationship of self esteem with forward head posture and round shoulder. Procedia
Soc Behav Sci, 2011, 15: 3698–3702. [CrossRef]
11) Borstad JD: Resting position variables at the shoulder: evidence to support a posture-impairment association. Phys
Ther, 2006, 86: 549–557. [Me dlin e]
12) Lau HM, Chiu TT, Lam TH: Measurement of craniovertebral angle with electronic head posture instrument: criterion
validity. J Rehabil Res Dev, 2010, 47: 911–918. [Me dli ne] [CrossRef]
13) Kang JH, Park RY, Lee SJ, et al.: The effect of the forward head posture on postural balance in long time computer
based worker. Ann Rehabil Med, 2012, 36: 98–104. [Me dline] [CrossRef ]
14) Yoo WG: Effect of the Neck Retraction Taping (NRT) on forward head posture and the upper trapezius muscle during
computer work. J Phys Ther Sci, 2013, 25: 581–582. [Me d lin e] [CrossRef]
15) Yoo WG: Comparison of the forward head angle and the lumbar exion and rotation angles of computer workers using
routine and individually xed computer workstations. J Phys Ther Sci, 2014, 26: 421–422. [Med line] [CrossRef]
16) Kim YG, Kang MH, Kim JW, et al.: Inuence of the duration of smartphone usage on exion angles of the cervical and
lumbar spine and on reposition error in the cervical spine. Phys Ther Korea, 2013, 20: 10–17. [CrossRef]
17) Kim MS: Inuence of neck pain on cervical movement in the sagittal plane during smartphone use. J Phys Ther Sci,
2015, 27: 15–17. [Med line] [CrossRef]
18) Gak HB, Lee JH, Kim HD: Efcacy of kinesiology taping for recovery of dominant upper back pain in female seden-
tary worker having a rounded shoulder posture. Technol Health Care, 2013, 21: 607–612. [Med line]
19) Park HC, Kim YS, Seok SH, et al.: The effect of complex training on the children with all of the deformities including
forward head, rounded shoulder posture, and lumbar lordosis. J Exerc Rehabil, 2014, 10: 172–175. [Medl i ne] [Cross-
Ref]
20) Baghery H, Esmaeilzadeh M: Effect of different sitting posture on pulmonary function in students. J Physiol Patho-
physiol, 2011, 2: 29–33.