Iranian Journal of Ergonomics

Given the growing popularity of smartphones, they can be considered as important and influential issue in all aspects of life. As smartphones have increasingly become an integral part of every person's daily life, it can be an important factor in the development of spinal cord abnormalities (20). Accordingly it can be said that overuse of the smartphone causes users to be in poor condition (21), and due to the above mentioned consequences following inappropriate status, this common situation in users can be considered an important Risk Factor associated with the development of spinal malformations that can cause long-term disorders of the shoulder girdle area, the aim of this study was to investigate the effect of The duration of the use of a smart phone on the head and shoulders of people with 20 to 35 years of old.

 

The statistical population of this study was young people aged 20-35 with a smart phone residing in Kish Island in 2018. The sample of the study was 50 volunteers (25 men and 25 women) who were voluntarily and purposefully selected. The two groups of short and long term users were identified using the addictive form of smartphone addiction. In assessing upper limb posture, shoulder status was measured using the scapular index. The instrument used in this measurement was tape meter and the distances between the four zones were measured two by two; the four zones and two distances shown in Figure 1.
 

Figure 1. Shoulder position measurement to determine the scapular index by measuring 1) the distance between the end of the thoracic cavity and 2) the posterior side of the end of the thoracic spine in the thoracic region (30).

 
The cranio-vertebral (CVA) angle was used to measure the forward head angle, which was measured and using Kinovea software after shooting. At first two anatomical signs of the ear tragus and vertebrae 7C vertebrae were identified and marked with anti-allergic marker. To find the 7C vertebra in the subject, he was asked to bend his head three times and then, by touching the throat-like part, the 7C vertebra was identified at the end of the cervical vertebrae.

Figure 2. Angular positioning of the head using Kinova software

Then the subject was photographed. Finally, the image was transferred to the computer and, using the Kinova software, extended it to the same area on the horizontal plane and specified the craniofacial angle by connecting two specified points. (30).
Independent t-test was used to compare variables in two groups. Data was analyzed by SPSS 22 (SPSS Inc., Chicago, IL. USA). P-value<0.05 was considered significant.

In examining upper extremity status in both long-term and short-term mobile users, the head and shoulder positioning of the two groups was first investigated and the results are expressed in Table 1.
 

Table 1. Independent t-test results to compare head and shoulder positioning

In addition, the results of independent t-test showed (mean-standard deviation) the mean of 49.33 (5.83) in females and 47.38 (7.43) in males. It can be seen that there is no significant difference between the cranio-vertebral angle (head positioning) extracted with Kinova software in the two groups of males and females (0.436). Thus, given the absence of a significant mean difference between the two groups, it can be said that gender does not affect head position leaning toward or, in other words, does not determine the position of head. In addition, the results of independent t-test showed that the mean-standard deviation was 87.50 in females (3.98) and 92.05 in males (3.36). The difference between the means indicates that there is a significant difference between the scapular index (shoulder positioning) extracted in both male and female groups (0.002). Therefore, considering the mean difference between the two groups, it can be said that gender affects the condition of the rounded shoulder, or in other words, the rate of rounded shoulder fitness is higher in women than men.

 

The findings of this study showed that upper extremity status in the two groups was different, that means, long-term use of the smartphone affects the upper extremity status. Inappropriate physical consequences of using a cell phone incessantly and over a long period of time can cause damage to nerves, muscles, toes, arms, forearms, neck and shoulders and can finally cause pain and discomfort in the neck. Another part of the research findings showed that gender did not affect head positioning while leaning toward. This indicates the influence of non-gender factors. Habits and behaviors such as duration of digital use, inappropriate status, repetition of inappropriate use of digital equipment, can affect the head and neck area. In the study of the effect of gender on shoulder status, it was found that gender influenced the shoulder status of the studied samples and it was shown that rounded shoulder fitness was higher in women than men. Given this finding, it can be pointed out that gender can affect seating status, thereby causing disturbances in the shoulder area (38). This difference in sitting position can cause differences in the degree of curvature of the spine in the shoulder area (39), thereby causing disorders such as the rounded shoulder.

Overall, it can be said that prolonged use of a smart phone can cause musculoskeletal disorders in the shoulder and neck, which can have many consequences for the individual. To prevent these problems from occurring for the users, it is suggested that brochures should be provided to, offer information about prolonged use, the proper period, and how to sit and stand properly and in good physical shape when interacting with the device. Another suggestion is to design a software that will alert the user in case of inappropriate posture or long period of use.

 

The authors thank all those who helped them writing this article.

 

The authors declared that there are no conflicts of interest.