Information and communication technology (ICT) has become an important part of the lives of adolescents, the majority of whom regularly use computers for surfing the Internet, chatting, and playing games. At the same time, the prevalence of neck-shoulder and low back pain has increased among adolescents [1]. Studies among adolescents confirm a connection between musculoskeletal symptoms and the use of ICT, especially computers. Headache [2–4], neck-shoulder pain and low back pain [4–7] are more common among computer users than non-users. The risk of developing musculoskeletal pain increases with an increase in the amount of time spent on the computer [5]. Moreover, computer users' agree that computer use causes these symptoms. The findings of several studies indicate that computer use induces pain and discomfort not only in the neck-shoulder and back regions, but also in the hands, fingers, wrists, eyes, and head [8–11]. Earlier studies focused mainly on examining the relationship between pain and computer use, but there is no information on the seriousness of these symptoms and how much these symptoms affect the everyday lives of adolescents.

When assessing children and adolescents, the visual analogue scale (VAS) [12] is often used to quantify the intensity of musculoskeletal pain [13–17]. Very little is known, however, about the intensity of pain due to computer use. Konijnenberg et al. [18] described and quantified impairment due to chronic pain from an unknown cause in a study with 149 children (mean age 11.8 years). They reported that children report impaired functioning in multiple domains of daily life due to musculoskeletal pain. Roth-Isigkeit et al. [19] investigated the prevalence and characteristics of pain (e.g. pain intensity) among 735 children and adolescents (aged 10-18 years). Girls reported pain that was significantly more severe than did boys, and half of the sample reported pain lasting longer than 3 months. Among young computer users, Breen et al. [20] investigated discomfort and posture while using computers in a small sample of 68 schoolchildren (mean age 9.5 years), finding that 16% of the children reported pain, mostly in the neck or back region, at the beginning and end of a computer session. Pain intensity increased during the session [20].

In the present study, we aimed to evaluate the intensity of computer-associated musculoskeletal pain and the level of inconvenience to everyday life caused by musculoskeletal symptoms among adolescent computer users.

A third (35.4%) of the respondents reported that they spend 14 or more hours a week using computers. Boys used computers more often than girls (p = 0.0001); half of the boys (50%, N = 98) and almost a quarter of the girls (23%, N = 51) used computers for 14 hours or more per week, which corresponds to 2 hours or more of daily use. The time spent using computers increased with age (p = 0.0001) among both sexes.

Mild pain in the lower back, head, and eyes was significantly related to computer use of 14 or more hours/week and 3.6 to 13.99 hours/week. Mild inconvenience to everyday life was significantly associated with pain in the low back and eyes when computer use was 14 or more hours per week (Table 2).

The responses to two independent questions indicated that adolescents experience a low level of musculoskeletal pain with little effect on everyday life. On the other hand, our findings indicate that computer use of 14 or more hours/week (corresponding ≥ 2 hours/day) is related to moderate/severe computer-associated pain at all measured anatomic sites. Moreover, computer use of 14 or more hours/week was related to moderate/severe pain in the lower back and head, which affected the everyday lives of adolescents. Girls reported greater pain intensity and more inconvenience to everyday life due to pain at all anatomic sites than boys, and the prevalence rates increased with age.

To the best of our knowledge, this is the first study to evaluate pain intensity and level of perceived negative impact on everyday life related to computer use in adolescents. Our results suggest that computer use of 14 or more hours/week (estimated ≥ 2 hours/day) is related to severe or moderate pain. Computer use exceeding 2 hours/day is suggested to be a threshold for neck-shoulder pain [5] neck-shoulder pain is associated with 1 or more hours/day spent on the computer [11, 23].

In our study, the pain intensity was lower than that reported in some previous studies [18, 19, 24], but approximately the same level as in the Finnish follow-up study by Saarni et al. with 88 participants [17]. Our results confirm earlier findings, that girls report more severe pain than do boys [18, 19].

In the present study, the intensity of pain and inconvenience to everyday life were measured using the well-documented visual analogue scale, VAS. The VAS has been extensively studied and has shown good acceptability, responsivity, and validity for most children aged 8 years and older [25]. Before analysis of the data, pain intensity categories were defined based on the findings of Collins et al. [26]. Musculoskeletal symptoms in five anatomical locations were evaluated by two independent questions. These anatomical sites had been related to computer use in previous studies. The first question measured musculoskeletal symptoms in general with no reference to computer use. The second one measured musculoskeletal pain that children themselves attributed to their computer use. Using two different questions gives a more reliable picture and a wider perspective to the association between musculoskeletal symptoms and computer use. The questions and their VAS categories were stated in different sections of the questionnaire; computer-associated pain was stated in the ICT-section and musculoskeletal pain in the section concerning health status.

There are some limitations to the present study. The convenience sample of the present study does not necessarily represent the entire population of that age, although it is unlikely that this would influence the studied relationships. Due to the cross-sectional design of the study, we are restricted to investigating the contemporary relations in our data, and thus causal inferences cannot be made based on this study alone. As the questions used in the study measured the respondents' perception of the intensity of computer-associated pain, it was a subjective measure. Thus it was left to the respondents to report whether these symptoms were due specifically to computer use. Being a questionnaire survey, the rate of occurrence of computer -associated and musculoskeletal symptoms, the pain intensity and inconvenience to everyday life were based on self-reports, and therefore memory bias is possible and differences between individuals' interpretations cannot be ruled out [27]. Respondents reported the weekly duration of computer use in response to an open question. There may be misreporting and overestimation of the duration of adolescents' computer use especially if there are different procedures to measure computer time [10]. In adults, the use of self-reports can lead to the misclassification of computer exposure for more than 80% of respondents [28]. In a previous study of adults self-reported duration of computer use but not recorded computer exposure, was positively associated with upper extremity symptoms [29]. A study using a computer-based program showed that the use of a computer mouse predicted acute neck-shoulder pain, but not chronic neck-shoulder pain [30]. Overall, based on an overview of systematic reviews, computer work has been associated with upper extremity musculoskeletal symptoms, but the causal relationship between computer work and symptoms shows a more mixed level of evidence [31]. We also do not know either if the mechanisms by which computer use elicits pain differ between adults and adolescents. Future studies with longitudinal designs are needed to examine the persistence of musculoskeletal symptoms, with accurate measurements of computer use and to evaluate the changes between symptoms and computer use.

The findings of the present study suggest that musculoskeletal symptoms causing moderate and severe pain as well as inconvenience to everyday life are common among adolescent computer users. Daily computer use of 2 hours or more increases the risk at most anatomic sites.