Pain and electromyography reduction cause of sitting upright posture,frequent break,eye rest and self-stretching during smartphone usage

Abstract

BACKGROUND:

Prolonged use of the smartphone causes neck and shoulder pain. However, no study has yet evaluated the effects of sitting upright, combined with frequent breaks, eye rest and self-stretching on pain and EMG during smartphone use.

OBJECTIVES:

The purpose of the study was to compare pain and muscle activity between the control group (rest only) and the intervention group (rest combined with correct posture, eye rest and self-stretching) in smartphone use for 41.30 minutes.

METHOD:

Forty-four healthy females aged 18–25 years old were recruited and randomly divided into two groups. The body pain chart and Visual Analog Scale (VAS) were used to evaluate pain. Electromyography (EMG) was used to measure muscle activity of Cervical Erector Spinae (CES) and Upper Trapezius (UT) muscles.

RESULTS:

The results showed that overall pain and neck pain in the control group increased significantly after smartphone use for 20 min and continually increased to 41.30 minutes (p < 0.05). Overall pain and neck pain in the intervention group was significantly lesser than control group after smartphone use for 41.30 minutes (p < 0.05). In the control group, EMG of CES at 41.30 minute was significantly higher than that of at 0 min (p < 0.05). There was no significant difference in EMG of UT between the two groups.

CONCLUSION:

Conclusion smartphone user in the interventional group reported less pain when compared to control group after Smartphone use for 41.30 minutes. Therefore, the user aged 18–25 years should have a rest combined with correct posture, eye rest and self-stretching to prevent neck pain during prolonged smartphone use.

Keywords

Mobile phone sitting straight spinal alignment discomfort muscle activity

1 Introduction

Smartphone has been used widely in daily life. Some countries discovered that there were 20.4 million smartphone users, which increased to 27 million people over three years, with a growth rate of 15 percent. 55.8% of users were found to be female and 42.4% were found to be male [1, 2]. The age of the user was predominantly 15–34 years old, followed by 35–50 years old [3]. Exploring the internet was the most popular use of the smartphones with an average of 5.7 hours per day use, which is mainly used for social networking and search engines were used for information. For social networking, Facebook was most often accessed (up to 92.1%), followed by Line and Instagram [4].

Musculoskeletal pain and poor posture were found in IT use. Smartphone use caused neck pain in university student [5]. Tablet use on an individual’s lap over long durations was a main cause of neck pain [6, 7]. In addition, smartphone use for 20 min in 3 postures which were on the lap level, on the chest level and on the table level increased pain significantly at neck, shoulder, upper back and arm areas [8]. Poor posture was found in users who were at a 65 degree angle of neck flexion, whereas in stand and sit positions showed only a 16 degree angle flexion of the neck [9]. Increased neck flexion angle during smartphone and tablet use increased moment arm on cervical spine which causes injury on the cervical spine and skin tissue surrounding the neck region [10, 11]. In addition, neck, thoracic and lumbar were found in flexion potion during smartphone use [12]. A previous study found that muscle pain in most people was around the Levator scapulae (neck) and Upper trapezius muscles, respectively [13].

Muscle activity of the neck and shoulder region was recorded as high during IT device use. Upper trapezius and Cervical erector spinae muscles suffered fatigue mostly in a 50 degree neck flexion angle after smartphone use for 10 min [14]. Pain pressure threshold of the Levator scapulae muscle decreased significantly after computer use for 30 min and 60 min [14]. Muscle activity of Cervicle erector spinae increased noticeably after smartphone use on lap level, chest level and on the table, when compared to the beginning of the session. Interestingly, muscle activity of Cervical erector spinae increased up to 50% of the maximum voluntary contraction (MVC) during smartphone use [8]. Muscle activity of Extensor pollicis longus and Abductor pollicis muscles increased significantly in smartphone use with two hands when compared to one hand use [16].

There are many guidelines for users when using smartphones. Avoiding sustained posture decreased discomfort in users. Instruction to change the position every 15–20 min and rest every 30–60 min are recommended [17]. Rest between computer use helped to prevent muscle fatigue, headache, eye and upper extremity pain. Changing the position and muscle stretches are suggested during rest time to prevent any musculoskeletal problems [18]. It was found that rest after smartphone use for 20 min decreased pain more significantly than rest after 40 min, or any preferred rest time [19]. In addition, rest combined with stretching showed reduction of pain clearly in the musculoskeletal system [20]. Furthermore, sitting upright is one of the most important pieces of advice. It was found that pop-up screen warnings to look ahead, specifically look at the wall in front of you, at eye level helped to reduce pain significantly [20]. In addition, self-stretching of muscles decreased pain considerably in the group of people who work in sitting posture for long periods [21]. During rest time, adding of stretching helped to decrease pain in the musculoskeletal system [22]. Moreover, eye rest is recommended by looking forward about 3 meters for 15 seconds [23]. Therefore, frequent breaks is essential [24]. Some studies found that a combining of correct posture and stretching are recommended for the user [25].

Diagram 1

Activity of smartphone use of control group (above) and interventional group (below).

However, no study has yet evaluated the effect of pain and EMG reduction on the frequency of breaks, correct posture, eye rest and self-stretching during smartphone use. The purpose of the current study was to compare pain and muscle activity at neck and shoulder between intervention group (rest, correct posture, eye rest and self-stretching) and control group (rest only) in smartphone users, aged 18–25 years old. The hypotheses of this study were: 1) pain at neck and shoulder would be different between intervention and control groups; 2) muscle activity of CES and UT would be difference between two groups.

2 Material and method

This study had an experimental design. Forty-four healthy females aged 18–25 years old without musculoskeletal disorders who had not taken any analgesic and muscle relaxants 24 hours prior to participating in the study were recruited into the current study. All participants had normal corrected eye vision, were right hand dominant and partook in regular smartphone use at least 2 times/week and 2 hours/week [26].

This study was approved by the Human Ethic Committee (HSPT2015-022). Participants were provided a consent form and were divided randomly into the control group (rest only) and intervention group (rest, sitting upright and correct posture, eye rest and self-stretching). Both groups performed the tasks, which were using Facebook for 20 min (min) by holding the smartphone with two hands at chest level [19, 27] and rest breaks for 1.30 min after smartphone use for 20 min. Participants sat on a chair with no backrest or armrest and placed their feet on the floor. Surface electrodes were placed at muscle fiber of Cervical erector spinae (CES) and upper trapezius (UT) muscles to measure muscle activity; known as maximum voluntary contraction (MVC) [26]. MVC was recorded during voluntary isometric contraction for 3 seconds, 3 times/muscle (CES: Neck extension and UT: Shoulder elevation). After measurement of MVC, participants took a rest for 5 min [28]. Participants started to use smartphone for 20 min, rest for 1.30 min and use it again for 20 min (Diagram 1). The room environment was controlled including light, noise, and room temperature.

2.1 Activity during smartphone use

2.1.1 Control group

Participant sat with preferred posture and used smartphone. Rest time was set after smartphone use for 20 min, during which participants were able to put their hand on their lap during rest time. Afterwards, take a rest for 1.30 min; participant used smartphone continually for 20 min (Fig. 1).

Fig. 1

Posture of smartphone user in the control group.

2.1.2 Intervention group

Participant was instructed to sit upright and prompt themselves to correct their posture at the start. Rest time was set after smartphone use for 20 min, where participants stopped using the smartphone, corrected their posture by sitting upright and looked forward for about 3 meters for 15 seconds [25] and, then, performed self-stretching of 3 muscles following the instruction video at CES, UT and LS at both sides while holding the stretch for15 seconds in each position. Overall, rest time was 1.30 min. After taking a rest for 1.30 min, participant used the smartphone continually for 20 min (Fig. 2).

Fig. 2

Posture of the intervention group during smartphone use: sitting upright (A), eye rest (B), self-stretching at upper trapezius (C), self-stretching at levator scapulae (D).

2.2 Pain measurement

Location and severity of pain were collected using a body pain chart and Visual Analog Scale (VAS), respectively at 0, 20 and 41.30 min. VAS is widely used to measure pain level in adults with correlation coefficient of 0.97–0.099 [29]. Rating from 0 to 10, with 0 meaning no pain and 10 meaning severe pain was reported by participant. Modified body pain chart showed two locations of pain at neck and shoulder regions. Overall pain measurement was recorded as painful summated from all regions that participants reported pain. Neck pain was recorded as painful which occurred at the neck region from C1 to C7. Shoulder pain was recorded as painful which occurred from C7 laterally to acromion process.

2.3 Muscle activity measurement

Surface EMG was used to measure muscle activity of ECS and UT muscles. EMG was collected 2 min at the time at 0–2, 18–20 and 39.30–41.30 min. Muscle activity data was collected by using Noraxon program with sampling of 1,500 Hz. Raw EMG data was rectified with Band-pass filter of 16–500 Hz and the Root Mean Square was calculated and smoothed at 100 ms to delete noise of signal. EMG was normalized by calculation compared to MVC of each muscle.

2.4 Statistical analysis

Kolmogorov Smirnov test was used to calculate the normal distribution of data. Independent pair t–test was used to compare overall pain, neck pain, shoulder pain and muscle activity between the control and interventional groups. One-way repeated ANOVA was used to compare the value of overall pain, neck pain, shoulder pain, and muscle activity among specific times at 0, 20 and 41.30 min. Data analysis was calculated by using SPSS program version 23.

3 Results

3.1 Characteristics of participant

Forty-four healthy females aged 18–25 years old were divided into two groups. The body weight of the control group (n = 22) was 43.00–69.40 kg ( $\bar{x}$ ±SD = 56.11±7.75 kg) and height was 150–173 cm ( $\bar{x}$ ± SD = 161.86±5.63 cm). The body weight of the interventional group (n = 22) was 45–75 kg ( $\bar{x}$ ±SD = 51.75±7.34 kg) and height was 150–168 cm ( $\bar{x}$ ±SD = 160.23±4.61 cm)

3.2 Pain

3.2.1 Tendency of overall pain, neck pain and shoulder pain at 0, 20 and 41.30 min in the control and intervention groups

Overall pain and neck pain in the control group increased significantly from 0 min to 20 min (p < 0.05) and continually to 41.30 min (p < 0.05). On other hand, the intervention group’s overall pain and neck pain increased significantly at a gradual rate form 0 min to 20 min (p < 0.05), but the overall pain and neck pain did not increase from 20 to 41.30 min. Shoulder pain in the control and intervention groups were found to be similar as results varied significantly and gradually from 0 to 20 to 41.30 min (Graph 1).

Graph 1

Comparison of groups in overall pain, neck pain and shoulder pain at 0, 20 and 41.30 min.

3.2.2 Comparison of overall pain, neck pain and shoulder pain between the control and intervention groups at 20 and 41.30 min

There was no significant difference in neck and shoulder pain between the control and intervention groups at 20 min, but overall pain and neck pain of the intervention group were significantly lower than the control group at 41.30 min (p < 0.05). There was no significant difference in shoulder pain between the control and intervention group at 20 and 41.30 min (Graph 2).

Graph 2

Comparison between the control and intervention groups of overall pain, neck pain and shoulder pain at 20 and 41.30 min.

3.2.3 Severity of pain in the control and intervention groups

There was no difference in the number of participants reporting mild, moderate and severe pain at 20 min. The number of participants reporting mild pain in the control group (n = 10) was lower than the intervention group (n = 14), but the number of participants reporting moderate pain in the control group (n = 8) was higher than in the intervention group (n = 4) (Table 1).

Table 1
Number of participants reporting pain and severity of pain at 20 and 41.30 min in the control and intervention groups

Pain scale (0–10) [30] Location of pain Time Group of smartphone user

20 minutes 41.30 minutes

Control Number of participants reporting pain (per cent) Intervention Number of participants reporting pain (per cent) Control Number of participants reporting pain (per cent) Intervention Number of participants reporting pain (per cent)

No pain Neck 4(18.18%) 5(22.73%) 3(13.64%) 4(18.18%)

(0–0.04) Shoulder 3(13.64%) 6(27.27%) 3(13.64%) 3(13.64%)

Mild Neck 14(63.64%) 14(63.64%) 11(50%) 14(63.64%)

(0.05–4.4) Shoulder 15(68.18%) 12(54.55%) 10(45.45%) 15(68.18%)

Moderate Neck 4(18.18%) 3(13.64%) 8(36.36%) 4(18.18%)

(4.5–7.4) Shoulder 3(13.64%) 4(18.18%) 8(36.36%) 4(18.18%)

Severe Neck 0 0 0 0

(7.5–10.0) Shoulder 1(4.55%) 0 1(4.55%) 1(4.55%)

Pain scale (0–10) [30]	Location of pain	Time Group of smartphone user
No pain	Neck	4(18.18%)	5(22.73%)	3(13.64%)	4(18.18%)
(0–0.04)	Shoulder	3(13.64%)	6(27.27%)	3(13.64%)	3(13.64%)
Mild	Neck	14(63.64%)	14(63.64%)	11(50%)	14(63.64%)
(0.05–4.4)	Shoulder	15(68.18%)	12(54.55%)	10(45.45%)	15(68.18%)
Moderate	Neck	4(18.18%)	3(13.64%)	8(36.36%)	4(18.18%)
(4.5–7.4)	Shoulder	3(13.64%)	4(18.18%)	8(36.36%)	4(18.18%)
Severe	Neck	0	0	0	0
(7.5–10.0)	Shoulder	1(4.55%)	0	1(4.55%)	1(4.55%)

Fig. 3

Application of EMG and placement of electrode at CES and UT muscles.

3.3 EMG of CES and UT muscles during smartphone use.

3.3.1 Tendency of muscle activity of CES and UT at 0, 20 and 41.30 min

EMG of CES in the control group did not differ from 0 min to 20 min but increased significantly at 41.30 min (p < 0.05), whereas EMG of CES in the intervention group increased significantly from 0 to 20 min (p < 0.05), but did not differ from 20 to 41.30 min. EMG of UT in both the control and intervention groups did not differ from 0 to 20, and to 41.30 min (Graph 3).

Graph 3

Comparison of EMG of CES and UT at 0, 20 and 41.30 min.

3.3.2 Comparison of EMG of CES and UT between the control and intervention groups at 0, 20 and 41.30 min

There was no significant difference in EMG of CES between the control and intervention groups at 0, 20 and 41.30 minute. Similarly, there was no significant difference in EMG of UT between the control and intervention groups at 0, 20 and 41.30 minute(Graph 4).

Graph 4

Comparison between the control and intervention groups of EMG of CES and UT between 0, 20 and 41.30 min.

4 Discussion

This study found that overall pain, neck pain and shoulder pain in the control group increased significantly after smartphone use for 20 min (p < 0.05) and continually to 41.30 min (p < 0.05). This finding was in line with a previous study which found that smartphone use for 20 min led to pain in many areas because the user did not rest, correct posture or performed stretches [8]. Also, pain was found in smartphone users at neck and shoulder regions [31]. A previous study found that after smartphone use with no rest, 84% of users had pain in one area of the body [32]. This can be explained as during smartphone use, users sat in poor posture and sustained positioning with no rest for a substantial period of time [26]. This caused an injury at the sarcoplasmic reticulum (SR) which leads to the release of calcium outside of the cell which induces adverse effects of muscle contraction. As a result, blood circulation and oxygen concentration decreased and chemical products increased to aggravate pain during smartphone use in the control group [33].

This study found that overall pain and neck pain in the control group was higher than that of the intervention group at 20 min, and also more significantly at 41.30 min. In addition, after smartphone use for 41.30 min, a number of participants reported in high level of moderate and severe pain at the neck and shoulders in the control group, whereas a number of participants in the intervention group reported only no pain and mild pain. The results of this study clearly convey that a combination of sitting upright, correcting posture, eye rest and self-stretching helped to prevent musculoskeletal pain in many areas of the body. This finding is related to previous study which discovered that frequent breaks during use of smartphones helps prevent neck and shoulder pain [20]. Neck and shoulder pain at moderate to severe level was found after smartphone use for 20 min with no breaks [8]. Similarly, IT users reported muscle fatigue at neck and shoulders [26]. Additionally, IT users who had rested at 20 min displayed less discomfort when compared to smartphone users participating in smartphone use for 40 min [19]. Hence, rest after use of smartphones for 20 min helps prevent pain and fatigue.

Self-stretching was added into the protocol of this study. The user was instructed to perform stretching 1 time at both sides of the upper trapezius and levator scapulae muscles. The results showed that mild stretching of neck muscles helps prevent neck and shoulder pain. Stretching of neck and shoulder muscles in between work sessions decreased pain significantly [21]. These instructions encourage other IT user to stretch muscles and hold the stretches for 10–30 seconds at a time [34]. Surprisingly, stretching only 1 time displayed the same effect as stretching a total of 3 times [35].

Sitting upright and correcting posture during smartphone use protected neck and shoulders from pain. In this study pop-up screen warnings were prompted to remind users to sit upright at the beginning of the session and correct posture during smartphone use. Sitting upright posture led to good alignment of lumbar, thoracic and the cervical spine caused by body linkage which was found in the interventional group of the present study. Similarly, to previous study, neck alignment helped to reduce the load on the cervical spine, which led to less pain at neck and should regions [36]. Sitting in a slouched posture in the control group was related to previous studied which found that during smartphone use, degree of flexion of cervical and upper thoracic increased significantly, especially in the texting task [37, 38].

In addition, previous study found that sitting upright decreased significantly pain level in the musculoskeletal system [20]. Proper sitting postures were head, spine and chest in neutral positions [39]. It has been found that users with heavy use of smartphones suffer from forward head syndrome and slouched posture which induced head flexion, high upper back kyphosis and less lumbar lordosis. In this position, users have less curvature of the spine, particularly at the lower cervical and increased high curvature of the upper thoracic and less lordotic curve of lumbar spine. High neck flexion leads to high compression force on the cervical spine and high muscle contraction of the neck, which has effects on muscle pain at neck and shoulders [40]. It was understood that smartphone use longer than 4 hours/day causes forward head flexion combined with rounded shoulders [41].

IT users were recommended to rest eyes away from the screen by looking forward approximately 3 meters for 15 seconds at a time [23] because the user tends to blink less than usual, causing eye strain. This method helped to reduce eye coordination which decreased the effect to eye fatigue, strain, and headaches [42].

Muscle activity of CES at 41.30 in the control group increased significantly when compare to that of at 0 min (Graph 4). This finding related to previous study which found that muscle activity of CES had increased significantly when compared to the start of the session [8]. The current study also found that the intervention group did not differ in muscle activity of CES between at 0 and 41.30 minute. This can be explained as those users sat upright at the beginning of the session and corrected their posture during rest times and performed stretching of neck and shoulder muscles, which helps to increase the flexibility of muscles and also increased blood circulation within the muscles. Additionally, stretching also helped maintain a good alignment of joint and muscles surrounding the spine. The finding of this study is similar to previous study regarding slumped posture, with neck flexion position, induced high muscle activity of CES. Neck flexion position increased neck muscle activity during smartphone use and increased risk of musculoskeletal disorders [43, 44].

Muscle activity of the upper trapezius (shoulder muscle) did not show any difference after smartphone use for 41.30 min. Both groups held the smartphone at chest level, so the shoulder was in a relaxed position with no elevation of the shoulders. Furthermore, the smartphone is a light device, therefore users did not exert shoulder muscle activity, even at 41.30 min. This finding is in line with a previous study in which EMG of UT worked in the same activity in different positions of smartphone use [6]. This study found that muscle activity of CES and UT did not show any difference between the control and intervention groups even when users performed different protocols. Users should hold the smartphone with both hands at chest level in order to keep a good distance between the screen and the eyes and avoid neck flexion and raised shoulders. So, EMG beard no significant difference. Previous study found that smartphone use on the lap induced a neck flexed posture where the user attempted to view information on the screen which led to fatigue of UT muscle [45].

4.1 Limitations

This study was evaluated in the laboratory. Therefore, it would be beneficial to examine the results in global situations, such as in house, public transport or outdoor environments. In addition, this study was limited in the evaluation because it only involved university students. This program should be studied onto other age groups, including high school students and middle-aged individuals who often use smartphones.

5 Conclusion

Sitting upright posture, frequent breaks, eye rest and self-stretching prevented smartphone use from causing neck pain and overall pain. The pain in the control group increased significantly after smartphone use for 20 min and increased continually up until 41.30 min, but in the intervention group, pain increased only from 0 to 21.30 min, however displayed no increase after that. Neck, shoulder and overall pain in the control group were higher than those of the intervention group; clearly shown at 41.30 min. EGM of CES in the control group increased significantly at 41.30 minute when compared to 0 min, but there was no evidence in the intervention group. We would encourage the smartphone user aged 18–25 years to sit upright, have frequent breaks, perform stretches and take an eye rests during smartphone use to reduce the risk of musculoskeletal disorders.

Conflict of interest

None to report.

References

Nielsen informate mobile insight. [Internet]. Vserv: Sagar Phadke; 2015. Vserv unveils the first Smartphone User Persona Report (SUPR) in Thailand [cited 2021 May 19]; Available from: https://www.vserv.com/vserv-unveils-firstsmartphone-user-persona-report-supr-thailand/

eMarketer. [Internet]. Marketeer today: Marker team; 2015. Smartphone is important on shopping online market [cited 2021 May 19]; Available from: https://marketeeronline.co/archives/40301

IT24Hrs-technology for life. [Internet]. IT24Hrs; 2015. Results of survey of internet using [cited 2021 May 19]; Available from: https://www.it24hrs.com/2015/thailandinternet-user-profile-2015-2558

Thailand internet user profile 2015 [Internet]: Technology news, that is worth. 2015 [cited 2021 May 19]; Available from: https://www.blognone.com/node/71144

Namwongsa

, Puntumetakul

, Neubert

, Boucaut

. Factor associated with neck disorders among university student smartphone users. Work. 2018;61(3):367–78.

6.Young

, Trudeau

, Odell

, Marlinelli

, Dennerlein

JT.

. Touch-screen tablet user configurations and case-supported tilt affect head and neck flexion angles. Work. 2012;41(1):81–91.

Chiang

, Lui

. Exploration of the associations of touch-screen tablet computed used and musculoskeletal disorders. Work. 2016;53(4):917–25.

Intolo

, Sirininlakul

, Saksanit

, Kongdontree

, Thuwatorn

. Pain and muscle activity of neck, shoulder, upper back and arm during smartphone use with holding on the lap level, on the chest level and on the table in university student. Journal of Health Systems Research. 2016;10(3):351–60.

Lee

, Lee

, Choi

, Lee

, Shim

. Smart pose: Mobile posture-aware system for lowering physical health risk of smartphone users. CHI EA [Internet]. 2013 [Cited 2021 May 19]; April 2013:2257-66. https://doi.org/10.1145/2468356.2468747

10.

Hansraj

. Assessment of stresses in the cervical spine caused by posture and position of the head. Surg Technol Int. 2014;25:277–9.

11.

Albin

, CcLoone

. The effect of table tilt angel on user preference, posture, and performance. Work. 2014;47(2):207–11.

12.

Kim

, Kim

, Park

. Relationship analysis between body flexion angles and smartphone tilt during smartphone use. Int J Ind Ergon. 2020;80103034.

13.

Andersen

, Hansen

, Mortensen

, Zebis

. Prevalence and anatomical location of muscle tenderness in adults with nonspecific neck/shoulder pain. BMC Musculoskeletal Disorders. 2011;12:169–175.

14.

Lee

, Lee

, Park

. Effect of the cervical flexion angle during smart phone use on muscle fatigue of the cervical erector spinae and upper trapezius. J Phys Ther Sci. 2015;27:1847–9.

15.

Aboodarda

, Spence

, Button

. Pain pressure threshold of a muscle tender spot increases following local and non-local rolling massage. BMC Musculoskeletal Disord. 2015;16:1–10.

16.

Lee

, Hong

, Lee

, Won

, Yang

, Park

, et al. The effects of smartphone use on upper extremity muscle activity and pain threshold. J Phys Ther Sci. 2015;27:1743–5.

17.

International ergonomic association. [Internet]. IEA; 2016. Guidelines general recommendations for computer use; [cited 2015 Oct 22]; Available from: https://www.iea.cc/ECEE/guidelines.html

18.

HSE. [Internet] Health and safety: Health and safety executive. 2013. Working with display screen equipment (DSE); [Cited 2021 may 19] Available from: https://www.hse.gov.uk/pubns/indg36.pdf

19.

McLean

, Tingley

, Scott

, Rickards

. Computer terminal work and the benefit of microbreaks. Applied Ergonomics. 2001;32:225–37.

20.

Robbins

, Johnson

, Cunliffe

. Encouraging good posture in school children using computers. Clinical Chiropractic. 2009;12:35–44.

21.

Lee

, Gak

. Effects of self stretching on pain and musculoskeletal symptom of bus drivers. J Phys Ther Sci. 2014;26:1911–4.

22.

Marangoni

. Effects of intermittent stretching exercises at work on musculoskeletal pain associated with the use of a personal computer and the influence of media on outcomes. Work. 2010;36:27–37.

23.

Leah

. Exercises to reduce musculoskeletal discomfort for people doing a range of static and repetitive work [Internet].health and safety executive; 2011 [cited 2021 May 19]. 1-

24.

TechRepublic. [Internet] Wallen J; 2018. Five free apps to help remind you to take a break; [cited 2021 May 19]; Available from: https://www.techrepublic.com/blog/five-apps/five-free-apps-to-help-remind-you-to-take-a-break/

25.

Intolo

. Muscular pain during Smartphone use in three aged groups: Elementary school student, High school student and Office Worker. Journal of Health Systems Research. 2018;12(2):328–41.

26.

Straker

, Burgess-Limerick

, Pollock

, et al. The impact of computer display height and desk design on 3D posture during information technology work by young adults. J Electromyogr Kinesiol. 2008;18(2):336–49.

27.

Straker

, Jones

, Miller

. A comparison of the postures assumed when using laptop computers and desktop computers. Applied Ergonomics. 1997;28:263–8.

28.

Greig

, Straker

, Briggs

. Cervical erector spinae and upper trapezius muscle activity in children using different information technologies. Physiotherapy. 2005;91:119–26.

29.

Karcioglu

, Topacoglu

, Dikme

. A systematic review of the pain scales in adults: Which to use? The American Journal of Emergency Medicine. 2018;36(4):707–15.

30.

Noble

, Clark

, Meldrum

, et al. The measurement of pain, 1945-2000. J Pain Symptom Manage. 2005;29:14–21.

31.

Waderich

, Peper

, Harvey

, et al. editors. The psychophysiology of contemporary information technologies tablets and smartphones can be a pain the neck. The 44st Annual meeting of the association for applied psychophysiology and biofeedback; 2013; Portland, OR.

32.

Berolo

, Wells

, Amick

. Musculoskeletal symptoms among mobile hand-held device users and their relationship to device use: A preliminary study in a Canadian university population. Applied Ergonomics. 2011:371-9.

33.

Fricton

. Myofascial pain. Clin Rheumatol. 1994;8:857–80.

34.

Nieman

. Musculaskeletal fitness. In: Ryam M, Glass W, editors. Exercise testing and prescription a health-related approach. New York, America: McGraw-Hill Companies; 2011:136–7.

35.

Bandy

, Irion

, Briggler

. The effect of time and frequency of static stretching on flexibility of the hamstring muscles. Phys Ther. 1997;77(10):1090–6.

36.

Tapanya

, Puntumetakul

, Neubert

, Boucaut

. Influence of neck flexion angle on gravitational moment and neck muscle activity when using a smartphone while sitting Ergonomics. 2021;64(7):900–911.

37.

Szeto

GPY

, Tsang

SMH

, Dai

, Madeleine

. Afield study on spinal postures and postural variations during smartphone use among university students. Appl Ergon 2020;88103183.

38.

Yoon

, Choi

, Han

, Shin

. Neck Muscular Load When Using a Smartphone While Sitting, Standing, and Walking. Human Factors: The Journal of the Human Factors and Ergonomics Society 2020;001872082090423.

39.

APTA [internet] American Physical Therapy Association; 1998. The secret of good posture a physical therapist’s perspective; [cited 2021 May 19] Available from: https://fliphtml5.com/zlwu/twsz/basic

40.

Park

, Kim

, Choi

. A Comparison of Cervical Flexion, Pain, and Clinical Depression in Frequency of Smartphone Use. International Journal of Bio-Science and Bio-Technology. 2015;7(3):183–90.

41.

Jung

, Lee

, Kang

, Kim

, Lee

. The effect of smartphone usage time on posture and respiratory function. J Phys Ther Sci. 2016;28:186–9.

42.

Live Science [Internet].Trending:RemyMalina; 2011.How Your Smartphone Affects Your Vision; [cited 2021 May 19]; Available from: https://www.livescience.com/15009-smartphone-affects-vision.html

43.

Ning

, Huang

, Hu

, Nimbarte

. Neck kinematics and muscle activity during mobile device operations. Int. J. Ind. Ergon. 2015;4810-15.

44.

Park

, Kang

, Lee

, Jeon

. The effects of smart phone gaming duration on muscle activation and spinal posture: Pilot study. Physiother. Theory Pract. 2017;33(8):661–669.

45.

Lee

, Lee

, Park

. Effect of the cervical flexion angle during smartphone use on muscle fatigue of the cervical erector spinae and upper trapezius. J Phys Ther Sci. 2015;27:1847–9.