Musculoskeletal Pain and Risk Factors Associated with Smartphone Use in University Students.

BACKGROUND: Smartphone has become a very popular necessity among students. An individual has to look at their phone's small monitor and perform repetitive movements in an awkward posture for a prolonged duration.
OBJECTIVES: To assess the prevalence of musculoskeletal pain and associated risk factors in university students because of smartphone usage. SUBJECTS AND METHODS: A cross-sectional study was conducted with 2000 university students using a semi-structured questionnaire comprising demographic profile, smartphone usage characteristics, presence of musculoskeletal pain, and specific area of pain according to the body region.
RESULTS: Among the 2000 students, 44.05% reported musculoskeletal pain. The most common sites of pain were the neck (34.2%), thumb (17.45%), lower back (16.7%), and elbow (16.6%). There was an association between prevalence of musculoskeletal pain with the size of the smartphone (P = 0.005), the predominant purpose of smartphone usage (P = 0.002), position preferred while using smartphone (P = 0.000), and the level at which smartphone is held during usage (P = 0.05). Logistic regression analysis revealed that the strongest predictor of musculoskeletal pain was the size of the smartphone.
CONCLUSION: The study reported that the prevalence of pain in smartphone users is high with common sites being neck, thumb, and lower back region. Also, the size of the smartphone had a significant association with musculoskeletal pain. Copyright:

INTRODUCTION

Technological advances, particularly, the invention of smartphones, have revolutionized our way of life. A smartphone operates analogously to computers with an operating system and numerous software applications. It is not only used for communication but also entertainment purposes, such as messages, music, media, internet access, photos, and games.[12]

Musculoskeletal disorder is defined as damage to the musculoskeletal structures as a result of repetitive motions, forces, and postures adopted during the execution of certain activities.[3] Smartphone forces an individual to look at their phone's small monitor and perform repetitive movements in an awkward posture for a prolonged duration, which can cause musculoskeletal disorders.[45] A recently published study showed that cell phones that promoted only thumb or only one finger usage during texting were associated with a high prevalence of musculoskeletal disorders.[6] Another study reported an 18.5% prevalence of musculoskeletal disorders in the upper extremity associated with smartphone usage with the most significant symptom found in the thumb.[7] Another study conducted in a Canadian university population revealed that 84% of participants reported pain in at least one part of the body with the thumb being the most common site.[8]

Smartphone users vary in age, ranging from students to elderly people.[9] However, students use smartphones for longer periods due to easy availability, low cost, portability, and multiple usabilities, combined with easy internet access. The combination of repetitive movements and poor posture can lead to musculoskeletal disorders, which, if ignored, may lead to long-term damage.[10]

Despite the hazardous effects of smartphones on the human body, there is less literature on musculoskeletal problems associated with smartphone usage in students. Hence, the present study aimed to assess the prevalence of musculoskeletal pain and analyze associated risk factors in university students because of excessive smartphone usage.

SUBJECTS AND METHODS

This is a cross-sectional study design, utilizing exploratory analysis. It was conducted using a convenient sampling method after approval of the Institutional Research Review committee. The study was conducted with 2000 university students in the age group of 18–25 years from February to April 2017. Inclusion criteria were the usage of smartphones for more than a year, both male and female students, who were willing to participate in the study. All students who had sustained any recent injury in the last six months—inflammatory, degenerative, cardiovascular, or neuromuscular condition—were excluded from the study. They were made aware of the purpose of the study and written consent was obtained from all participants.

An 18-item face validated semi-structured questionnaire was used. It was developed based on a literature review on previous epidemiological studies in smartphone users and recommendations from key stakeholders including physiotherapists.[67811] It is divided into three parts. The first part comprises demographic information—age in years, gender, dominance, height in centimeter, weight in kilograms, and body mass index in kilogram/metre2. The second part consists of information about smartphone usage—the size of the smartphone (inches), total duration of exposure to the smartphone (years), the predominant purpose of smartphone usage, position preferred while using a smartphone, and level at which the smartphone is held while using. The third part comprises the presence of musculoskeletal pain and specific area of pain according to the body region. The pain was defined as any self-reported pain present at the time of filling out the questionnaire. The body parts that are bilateral were counted as 2 site(s) when both were in pain. The assessor was present during questionnaire filling to address any queries. Face validity of the questionnaire was established with aid of a panel of experts comprising senior Physiotherapy faculty members. The approval from the Institutional Research Committee was obtained. Date of the approval - 19th January 2017.

Statistical analysis

Data analysis was performed using the Statistical Package for Social Sciences (SPSS version 20). Descriptive statistics were used to describe baseline characteristics using mean values and standard deviation (SD) for continuous variables or frequency and percentage for categorical variables. A Chi-square test was used to find an association between prevalence of musculoskeletal pain and demographic and smartphone usage characteristics:

Logistic regression analysis was further conducted to analyze the risk factors and was expressed as Odds Ratios with 95% Confidence Intervals. A P value less than 0.05 was considered to be statistically significant.

RESULTS

Demographic characteristics

Out of the 2000 students, 1040 (52%) were females and 960 (48%) males. The mean age of students was 22.06 ± 2.1 years. Table 1 presents the demographic and smartphone usage characteristics of the participants.

Table 1

Demographic and smartphone usage characteristics of students

Characteristics	Total Students (n=2000)
Age (years)	22.06±2.1
Height (in cm)	163.83±8.71
Weight (in kg)	62.15±11.29
Body mass index (kg/m2)	22.67±3.85
Gender [n (%)]
Male	960 (48)
Female	1040 (52)
Dominance [n (%)]
Right	1788 (89.4)
Left	212 (10.6)
Total duration of exposure to smartphone [n (%)]
0-5 years	1207 (60.35)
>5 years	793 (39.65)
Size of smartphone (inches) [n (%)]
≤4 inches	32 (1.6)
4 to 5 inches	1000 (50)
≥5 inches	968 (48.4)
Predominant purpose of smartphone usage [n (%)]
Calling	192 (9.6)
Texting	447 (22.35)
Gaming	189 (9.45)
Email	146 (7.3)
Internet surfing	358 (17.9)
Social networking	668 (33.4)
Position preferred while using smartphone [n (%)]
Standing	76 (3.8)
Sitting with support	712 (35.6)
Sitting without support	375 (18.75)
Lying on back	306 (15.3)
Lying on elbows	196 (9.8)
Slouch Sitting	302 (15.1)
Side Lying	33 (1.65)
Level at which smartphone is held while usage [n (%)]
Eye level	376 (18.8)
Below eye level	808 (40.4)
Near chest level	630 (31.5)
Near stomach	153 (7.65)
Hands on the lap	33 (1.65)

Pain profile

Among the 2000 students, 44.05% reported musculoskeletal pain. The most common site of pain was neck (34.2%), thumb (17.45%), lower back (16.7%), and elbow (16.6%) [Table 2].

Table 2

Pain profile of smartphone users: 12-month prevalence

	Males (n=960)		Females (n=1040)		Total Students (n=2000)
	n	%	n	%	n	%
Pain	420	43.75	461	44.33	881	44.05
Shoulder	121	12.6	112	10.77	233	11.65
Elbow	146	15.2	186	17.88	332	16.6
Wrist/Hand	37	3.85	46	4.42	83	4.15
Fingers	49	5.1	63	6.06	112	5.6
Thumb	170	17.7	179	17.21	349	17.45
Neck	364	37.92	320	30.76	684	34.2
Upper back	135	14.06	143	13.75	278	13.9
Lower back	174	18.13	160	15.38	334	16.7

Association between prevalence of musculoskeletal pain and smartphone usage characteristics

A chisquare test was administered to find an association between musculoskeletal pain and demographic and smartphone usage characteristics. Results demonstrated that the size of smartphones of 4 to 5 inches had the highest prevalence of musculoskeletal pain (P = 0.005). Also, there was an association between musculoskeletal pain with the predominant purpose of smartphone usage (P = 0.002), position preferred while using a smartphone (P = 0.000), and level at which the smartphone is held while usage (P = 0.05) [Table 3].

Table 3

Association between prevalence of musculoskeletal pain and smartphone usage characteristics in students using Chi-square test

Musculoskeletal pain	Yes n=881	No n=1119	Total n=2000	χ2 test, P
Gender
Male	420 (43.7)	540 (56.3)	960 (48)	0.795
Female	461 (44.3)	579 (55.7)	1040 (52)
Dominance
Right	778 (43.5)	1010 (56.5)	1788 (89.4)	0.160
Left	103 (48.6)	109 (51.4)	212 (10.6)
Total duration of exposure to smartphone
0-5 years	533 (44.2)	674 (55.8)	1207 (60.4)	0.904
>5 years	348 (43.9)	445 (56.1)	793 (39.6)
Size of smartphone
≤4 inches	23 (71.9)	9 (28.1)	32 (1.6)	0.005*
4-5 inches	429 (42.9)	571 (57.1)	1000 (50)
≥5 inches	429 (44.3)	539 (55.7)	968 (48.4)
Predominant purpose of smartphone usage
Calling	81 (42.2)	111 (57.8)	192 (9.6)	0.002*
Texting	227 (50.8)	220 (49.2)	447 (22.4)
Gaming	76 (40.2)	113 (59.8)	189 (9.4)
Email	76 (52.1)	70 (47.9)	146 (7.3)
Internet surfing	157 (43.9)	201 (56.1)	358 (17.9)
Social networking	264 (39.5)	404 (60.5)	668 (33.4)
Position preferred while using smartphone
Standing	28 (36.8)	48 (63.2)	76 (3.8)	0.000*
Sitting with support	330 (46.3)	382 (53.7)	712 (35.6)
Sitting without support	196 (52.3)	179 (47.7)	375 (18.8)
Lying on back	118 (38.6)	188 (61.4)	306 (15.3)
Lying on elbows	71 (36.2)	125 (63.8)	196 (9.8)
Slouch Sitting	118 (39.1)	184 (60.9)	302 (15.1)
Side Lying	20 (60.6)	13 (39.4)	33 (1.6)
Level at which smartphone is held while usage
Eye level	159 (42.3)	217 (57.7)	376 (18.8)	0.05*
Below eye level	337 (41.7)	471 (58.3)	808 (40.4)
Near chest level	288 (45.7)	342 (54.3)	630 (31.5)
Near stomach	77 (50.3)	76 (49.7)	153 (7.7)
Hands on the lap	20 (60.6)	13 (39.4)	33 (1.6)

*P<0.05 is statistically significant

Logistic regression was applied to identify the risk factors that may be independently associated with musculoskeletal pain among smartphone users. In the Chi-square test analysis, four variables (size of the smartphone, the predominant purpose of smartphone usage, position preferred while using the smartphone, and level at which smartphone is held while using) that showed significant association (P < 0.05) were considered in logistic regression analysis. Logistic regression analysis revealed that only the size of the smartphone was associated with musculoskeletal pain [Table 4]. Respondents who indicated using smartphones sized 4 to 5 inches and ≥5 inches were 3 times more likely to develop musculoskeletal pain than those who used ≤4 inches. Also, it was observed that there was a significant association of predominant purpose of smartphone usage (texting and email) and position preferred while using smartphone (sitting without support and side-lying) with musculoskeletal pain [Table 4]. However, the significant odds ratios were less than one reporting less likelihood for developing musculoskeletal pain.

Table 4

Logistic regression analysis of factors associated with musculoskeletal pain in smartphone users

Variable	Odds ratio (95% CI)	P
Size of smartphone
≤4 inches	Reference
4-5 inches	3.32 (1.49-7.39)	0.003*
≥5 inches	3.26 (1.47-7.24)	0.004*
Predominant purpose of smartphone usage
Calling	Reference
Texting	0.66 (0.47-0.94)	0.02*
Gaming	1.01 (0.66-1.54)	0.97
Email	0.61 (0.39-0.95)	0.03*
Internet surfing	0.88 (0.61-1.27)	0.49
Social networking	1.03 (0.74-1.44)	0.85
Position preferred while using smartphone
Standing	Reference
Sitting with support	0.72 (0.44-1.19)	0.2
Sitting without support	0.54 (0.32-0.91)	0.02*
Lying on back	0.93 (0.55-1.59)	0.79
Lying on elbows	1.03 (0.58-1.84)	0.9
Slouch Sitting	0.98 (0.57-1.69)	0.95
Side Lying	0.42 (0.18-0.98)	0.04*
Level at which smartphone is held while usage
Eye-level	Reference
Below eye level	1.13 (0.86-1.49)	0.37
Near chest level	0.88 (0.66-1.17)	0.36
Near stomach	0.82 (0.54-1.23)	0.34
Hands on the lap	0.49 (0.24-1.04)	0.06

DISCUSSION

This study explored musculoskeletal pain and analyzed risk factors in university students because of smartphone use. It was observed that 44.05% of students reported musculoskeletal pain. The most common site of pain was the neck followed by the thumb, lower back, and elbow.

The neck was the most common site of pain reported by students which is consistent with other studies. A recently published systematic review revealed that neck and/or shoulder symptoms are common in mobile touch screen users with prevalence rates ranging from 26.3% to 60%.[11] A study conducted on Canadian university students revealed that the neck, followed by upper back and shoulders were common sites of pain. Also, total time spent using a smartphone was significantly associated with pain in the neck and shoulder.[8] Another study showed that a head flexion angle of 33–45 degrees from vertical was maintained when using the smartphone. It revealed that repetitive and prolonged head flexion posture is a major risk factor for neck pain.[12] University students usually adopt static and flexed spinal posture during smartphone use considering their age.[13] This may cause faulty posture such as forward head, slouched posture, or rounded shoulders which leads to injury to the cervical and lumbar spine, as well as ligaments.[1415] A study reported that increased flexion of the head at varying degrees increases the weight borne by the cervical spine. This leads to loss of curvature, increased stress on the cervical spine, and hastens the process of degeneration of ligaments.[16]

Poor posture changes length-tension relationship of cervical spine and shoulder girdle muscles, altering the pattern of muscle activation. There is increased muscle activity observed in the upper trapezius, erector spinae, and neck extensor muscles during smartphone use.[1718] Also, it is reported in the literature that increased muscle activity is associated with an increase in muscle fatigue and reduction in the pain pressure threshold in the shoulder when using a smartphone.[1719] University students adopt inappropriate posture for prolonged duration combined with repetitive movement which may be a causative factor for neck pain.

In our study, university students used smartphones predominantly for social networking and texting which requires repetitive thumb movements. Research reports that musculoskeletal pain in the thumb is common in smartphone users due to text messaging.[7] During smartphone use, the thumb covers a large arc of motion in all three planes of movement simultaneously.[20] The motions of the thumb occur rapidly with thumb adduction and abduction almost twice as fast as flexion or extension. These repetitive and extreme ranges of thumb movements may be a predisposing factor for the development of musculoskeletal pain.[2122] A study conducted in Thailand showed that smartphone users with musculoskeletal disorders commonly adopted neck flexion, shoulder protraction, elbow flexion, wrist and hand flexion, upper back flexion, and lower back flexion positions during device usage. These awkward positions have a devastating effect on soft tissue structures leading to musculoskeletal discomfort.[23]

Logistic regression analysis showed that the size of the smartphone had a significant association with musculoskeletal pain. Literature reports that a larger screen size of a smartphone along with the placement position of the device poses the risk of musculoskeletal pain in the neck, shoulder, and upper limb.[2425] A recently published study evaluated the effect of screen size on upper extremity and trapezius muscle activity and cervical posture during a short texting task in college students. It showed that increased muscle activity was seen in finger flexors, wrist extensors, and trapezius along with cervical flexion posture as the screen size increased. These factors may put high stress on the musculoskeletal structures during texting leading to pain.[24]

Interestingly, the predominant purpose of smartphone usage and position preferred while using the smartphone can act as protective factors for musculoskeletal pain. The task performed and proper posture maintained while using a smartphone can help to reduce the stress on the musculoskeletal structures and incidence of pain.

The study has some limitations. It used self-administered questionnaire, which may increase the risk of response bias. Since this was a cross-sectional study, it is difficult to assume a causal relationship between exposure and outcome. Further studies using longitudinal study design can be conducted. We recommend that awareness, education, maintenance of proper posture, and strategies to develop strength of upper limb and shoulder girdle musculature among university students should be undertaken as preventive strategies to reduce the risk of musculoskeletal disorders.

CONCLUSION

The study indicated that the prevalence of pain in university students because of smartphone usage is high. Neck, thumb, and lower back were the common site of pain reported. Also, it was reported that the size of the smartphone had a significant association with musculoskeletal pain.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.