Differential patterns of laptop use and associated musculoskeletal discomfort in male and female college students

Abstract

BACKGROUND: Laptop computers have surpassed desktop computers in popularity, especially among college student users. The portability of these devices raises concerns regarding healthy usage patterns in different settings and there is a need to investigate the postures with which these devices are being used and associated reports of musculoskeletal discomfort.

OBJECTIVE: This study investigated the configurations in which laptops are used and the prevalence of musculoskeletal discomfort associated with laptop use in a survey of college students. The purpose of this was to identify differences in discomfort and/or postural choice between males and females.

METHODS: A sample of 90 male and 96 female college students completed an online questionnaire consisting of demographic questions, musculoskeletal discomfort indicators and questions regarding configurations of laptop use.

RESULTS: Over 53% of participants reported experiencing musculoskeletal discomfort while using a laptop computer, with females reporting a higher prevalence of neck discomfort (p = 0.05) and shoulder discomfort (p = 0.006) than males. Participants reported using a laptop most commonly in positions at a desk and on a bed. Females were more likely than males to use a laptop on a bed with the computer positioned on their lap or with their legs crossed (p < 0.05). Males were more likely than females to work in positions necessitating a large trunk deviation to operate the laptop (p < 0.05), such as “sitting on a sofa with your feet on the floor (knees at 90°), bending over to use laptop that is resting on a coffee table or ottoman in front of you”.

CONCLUSIONS: A significant proportion of college students report experiencing musculoskeletal discomfort associated with laptop computer use. Sex differences exist in both choice of configurations and musculoskeletal discomfort associated with laptop use. Due to the portability of laptop computers, they are used in a variety of configurations and environments. This study identifies a number of different ways that laptop computers are used that have not been considered in previous research. These patterns of laptop use can be used to inform future work on the impact of technology use on discomfort.

Keywords

Sex gender posture computer injury notebook computers

1 Introduction

College students use laptop computers in a wide variety of settings [1, 2]. The musculoskeletal risks associated with laptop use in offices are well known. Complaints of discomfort are most common in the neck, shoulder, and back, followed by the wrists and hands [3 –5]. Risk factors for upper extremity musculoskeletal disorders related to laptop use include the frequency and duration of computer use, time spent using the computer without a break,repetitive and forceful motions related to typing, awkward postures and frequent or prolonged static muscle contraction related to mouse use [6]. Previous work has found a higher prevalence of musculoskeletal discomfort associated with computer use in females than males, however it is unclear what the mechanism behind this might be [3 , 8]. It has been suggested that this sex difference could arise from differences in the tasks performed, the durations of computer use between males and females or postural differences when performing seated computer work [9, 10].

Laptop use results in static work postures in which the user positions his or her body in a fixed position relative to the location of the keyboard, mouse and display. This often results in sustained awkward trunk, shoulder, neck, elbow, and wrist postures [11 –15]. Unlike a desktop computer, the screen and keyboard on a laptop typically are connected, which restricts the adjustability of these components. Because of this, laptop users tend to exhibit more pronounced neck and trunk flexion than desktop users when typing, the degree of which has an inverse relationship with the size of the device [16 –18]. In addition, higher levels of neck, shoulder, elbow and wrist musculoskeletal discomfort, as well as eyestrain, have been reported during laptop use compared to desktop use [18].

Increased downward head tilt, neck flexion, and wrist extension, and reduced shoulder elevation, scapular protraction, flexion, and abduction have been found when the laptop is on the lap of the user [13, 19]. Poor work postures have also been observed in college students working in configurations on a sofa or bed [20]. Specifically, some seated positions are associated with neck flexion, shoulder abduction, trunk extension and elbow flexion greater than 90°. Lying prone results in neck extension, shoulder elevation, trunk extension, wrist flexion and less than 90° of elbow flexion. These findings are significant because college students are known to use their computers in a wide variety of settings and positions [1].

In order to fully assess the musculoskeletal risks associated with laptop use, it is important to understand how, where and how frequently these devices are being used. As mentioned, female computer users tend to report greater musculoskeletal discomfort than their male counterparts. One possible reason for this difference that has not been investigated is that females may choose to work in configurations that place them at a greater risk of discomfort or injury. The current study asked male and female college students to report how frequently they use their laptop computers in a number of possible configurations. The intention of this effort is to inform future work investigating the relationship between sex, laptop configuration, posture and musculoskeletal discomfort. In order to investigate these relationships, it is important to first understand what configurations are popular in everyday use and what differences exist between males and females. The results of this study should be used to inform researchers as to what configurations are relevant and warrant investigation. The following research question (RQ) and hypotheses (H) were investigated in this study:

What configurations do male and female college students frequently utilize while using a laptop computer?

Females will report a higher prevalence of musculoskeletal discomfort associated with laptop use than males.

There will be sex differences in terms of which configurations males and females report using a laptop computer in most frequently.

2 Methods

2.1 Participants

A total of 186 participants (148 undergraduate and 38 graduate students) volunteered to participate in a web-based questionnaire. All participants were current university students who owned a laptop computer. The sample was composed of 96 females with a mean age of 21 years (SD = 2.2 years) and 90 males with a mean age of 22 years (SD = 4.7 years).

2.2 Questionnaire

An online two-section questionnaire was developed using survey software (Qualtrics). The first section of the questionnaire asked for demographic information including their age, sex and whether they experience any discomfort associated with laptop computer use (yes/no). If participants indicated that they do experience discomfort, they were asked to indicate the location(s) of the discomfort (wrists, fingers, arms/elbows, shoulders, neck, upper back, lower back, other). Participants were able to specify a body region in the case that “other” was selected.

The second section of the questionnaire presented participants with a verbal description and corresponding image for 31 possible configurations in which a laptop could realistically be used for an extended period of time (see Fig. 1). This list was developed by brainstorming every conceivable configuration in which a laptop could be used in and then narrowing it down to those that realistically might be used for extended periods of time. Each configuration included in the questionnaire was simulated and photographed by the first author. This section included positions at a desk/table, on a bed, on a sofa, on the floor, etc. Participants were also given the option to manually write configurations that they use a laptop in that were not included in the questionnaire. Each question in this section asked participants to report how often they work in the described position by selecting from the following options: never, occasionally (less than 1 hour per week), 1–5 hours per week, 5–10 hours per week, 10–15 hours per week, over 15 hours per week.

2.3 Procedure

Participants were recruited through flyers that were posted throughout the campus of a large university in the northeast United States, and through emails that were sent to members of the departments of Design and Environmental Analysis, Computer Science, Psychology, Information Science, and Communication. Participants were entered in a draw for one of three $25 gift cards as incentive to participate in the study. Upon deciding to participate, each student accessed the questionnaire through a link provided on the flyer or in the email. The first page explained the purpose of the study, eligibility requirements, and possible risks. Completion of the questionnaire was taken as informed consent, as stated on the website. There was no time limit enforced, and the questionnaire took approximately 10–20 minutes to complete. The study design was approved by the Institutional Review Board of the University.

2.4 Analysis

All data were analyzed using a multivariate statistical package (IBM SPSS version 21). For many configurations the data were skewed towards the lower end of the response scale, and consequently, the categories “5–10 hours per week”, “10–15 hours per week”, and “greater than 15 hours per week” were combined into a single category labeled “greater than 5 hours per week”. Configurations that over 50% of the sample reported “never” using were not included in the analysis, thus omitting 11 configurations from analysis (Table 2). These configurations were removed from consideration because this study focused on those configurations that college students frequently use and whether there are any sex differences in these use patterns. If the majority of the sample did not work in a certain configuration, it was considered to be one that is infrequently used. Descriptive statistics were summarized using median responses because the scales were ordinal. Sex differences in self-reported musculoskeletal discomfort in specific body areas and in the frequency of laptop computer use in each configuration were tested using a Pearson chi-square test. The Benjamini-Hochberg procedure was used to correct for potential false positives that could arise due to the fact that a large number of comparisons were made.

3 Results

3.1 Musculoskeletal discomfort

Approximately half of the participants (53.8%) reported experiencing musculoskeletal discomfort when using a laptop computer, and overall there was no significant difference in prevalence between sexes (p = 0.909) (Table 1). However, females reported a significantly higher prevalence of neck discomfort (p = 0.05) and shoulder discomfort (p = 0.006) than males. The greatest prevalence of discomfort was reported in the neck (28.9% of males and 42.7% of females), wrists (24.4% of males and 29.2% of females), lower back (21.1% of males and 27.1% of females) and upper back (16.7% of males and 17.7% of females). Females also reported a high prevalence of discomfort in the shoulders (24% of respondents).

3.2 Time spent using a laptop in various configurations

The most common configuration for laptop use was “sitting in an office chair at a desk” (median response of >5 hours per week). “Sitting in a straight-back chair at a desk” and “sitting on a bed, leaning back against a wall or headboard, legs straight out, laptop resting on your lap” had median responses of 1–5 hours per week. All other configurations tested had a median response of never or occasionally (less than one hour per week).

Table 2 shows sex differences in response for each configuration. Females reported spending significantly more time than males “sitting on the floor, leaning against a wall or piece of furniture, legs straight out, laptop resting on your lap” (p = 0.022), “sitting on the floor with your legs crossed, laptop resting on the floor in front of you” (p = 0.009), “sitting on a bed, leaning back against a wall or headboard, knees bent, laptop resting on your lap” (p = 0.036), “sitting on a bed with your legs crossed, laptop resting on your lap” (p = 0.002), “sitting on a bed with your legs crossed, laptop resting on the bed in front of you” (p = <0.001), and “sitting in a lounge chair, laptop resting on your lap (i.e. chairs at a coffee shop)” (p = 0.045). Males reported spending significantly more time than females “sitting on a sofa with your feet on the floor (knees at 90°), bending over to use laptop that is resting on a coffee table or ottoman in front of you” (p = 0.031) and “sitting on a bed, leaning back against a wall or headboard, legs straight out, laptop resting on the bed beside you” (p = 0.031).

4 Discussion

Approximately half of the participants (53.8%) reported experiencing musculoskeletal discomfort associated with laptop computer use, which is consistent with previous studies of college students that have found the prevalence to be around 50% [21 –23]. In the students sampled in this study, discomfort was most frequently reported in the neck, wrists, and lower back, followed by the upper back and shoulders.

The hypothesis that females would report a higher prevalence of musculoskeletal discomfort associated with laptop use than males was only partially supported by the results of this study. Although there was no overall sex difference when asked about general musculoskeletal discomfort (yes/no response), sex differences emerged when participants were asked about specific body regions, and females were more likely to report shoulders and neck discomfort than males. This apparent discrepancy between overall discomfort and specific discomfort could have arisen because of the wording of the questions. While the general discomfort question wording might not have affected one sex more than the other, the follow up question asking participants to specify the location of discomfort may have prompted them to report specific discomfort that they had originally overlooked, providing a more accurate response than the original estimate. One of the limitations of self-report data is that it relies on memory, and recall can be influenced by prompting [24].

There are several possible mechanisms that could explain a higher prevalence of neck and shoulder musculoskeletal discomfort in females than males. Because females have a smaller skeletal system and a shorter reach distance than males on average, they may be required to adopt awkward postures more often, especially for configurations that restricts the position of the computer, such as with a desktop or on a table or desk of fixed height. These situations would require the user to conform his or her body to the position of the computer, rather than allowing for an adjustment of the position of the screen or keyboard. For example, the standard desk height of 73.7 cm correlates with the seated elbow height of a 1.9 m male, meaning that smaller individuals and the majority of women would have to conform their bodies in order to make the desk accommodate them [25]. It has also been suggested that differences in bone mass result in greater skeletal integrity in males than females, making females more susceptible to injury [26]. Specifically, the authors of this paper found that males tend to have thicker or wider bones than females, which may be correlated with greater biomechanical competence and a lower likelihood of injury. Because discomfort associated with computer use is a precursor to chronic injury when left unchecked, it could be extrapolated that females are more likely to experience discomfort, which is what was found in this study [27, 28]. Another explanation could be that the females in the sample were using a laptop more often or for greater durations than their male counterparts, which should be investigated explicitly in future studies. The current study captured this information indirectly by asking participants to estimate how much time is spent in each configuration every week. However, due to the number of configurations in the questionnaire, it is likely that these estimates are exaggerated.

There were sex differences in the frequency with which different configurations were utilized. In general, females were more likely to work in positions where their legs were crossed or the laptop was resting on their lap, while males were more likely to work in configurations that required large deviations of the trunk (e.g. “sitting on a sofa with your feet on the floor (knees at 90°)”, “bending over to use the laptop that is resting on a coffee table or ottoman in front of you” or “sitting on a bed, leaning back against a wall or headboard, legs straight out, laptop resting on the bed beside you”). This may reflect a sex difference in flexibility, as females often have greater flexibility in the hips and legs, which would make sitting with the legs crossed more comfortable and consequently more likely [29]. If it is the case that males are less likely to sit with their legs crossed due to flexibility or some other variable, one alternative way of positioning the laptop when sitting upright would be to sit with the laptop to the side of them, which is consistent with what was found in the results. These findings support the second hypothesis, that the patterns of laptop use would be different between males and females. The finding that females were more likely to work with the laptop positioned on the lap could provide an explanation for the higher prevalence of neck discomfort in this group. Previous literature has demonstrated increased neck flexion when a laptop is positioned on the lap of the user, which can lead to pain or discomfort when sustained [13 , 30].

The results suggest that college students spend most of their time using a laptop on a desk. This is consistent with previous work that has found that college students spend upwards of 80% of their time using a laptop computer at a desk [31]. However, the other settings that emerged as popular for laptop use in the current study were on a sofa and on a bed. This may reflect the fact that college students may not have a dedicated office or workspace in their home or dormitory. By providing an overview of the configurations and locations college students use laptop computers in, a more directed study could be conducted to understand risks associated with laptop use in popular configurations in contexts other than at a desk.

Only one other study was identified that measured posture while students used a laptop on a bed [20]. This study purported to investigate three commonly used positions, one of which was lying prone on a bed (the other two positions were: sitting on a sofa with feet on the ground and sitting on a sofa with feed on an ottoman). However, based on the results of the current study, lying prone is not one of the most frequently utilized configurations of use on a bed. It is important for future work to look at configurations that are used frequently in detail in order to understand the associated risks.

5 Limitations

This study was limited by the fact that it relied on participant memory of events that occurred in the past. Previous studies have shown that people have a tendency to overestimate durations in self report data [32]. Consequently, it could have been difficult for the participants to estimate exactly how long they spend in each configuration accurately. In addition, participants were not asked to report how much time they spent using a laptop in an average week, so we were unable to include this variable in the analysis. Asking participants directly to estimate how much time they spend using a laptop on a daily or weekly basis would be an easier task than asking them to calculate how much time was spent sitting in each different position and would likely yield a more accurate result than trying to combine the estimates for each position. Another option to get more accurate duration data would be to ask participants to record exactly how much time they spend using their laptop right after they do it, for a period of time such as a week. This value could then be extrapolated if deemed to be representative use by theparticipants.

Another limitation is that the questionnaire did not capture any data regarding the continuous durations of use in these configurations, work/rest patterns, nor any information regarding total time spent using a laptop. Future research could usefully investigate the duration of different patterns of laptop use and determine the extent to which this plays a role in musculoskeletal discomfort. Specifically, it has been shown that taking frequent breaks can significantly reduce the likelihood of discomfort in office workers, so it would be valuable to understand whether there are differences in break patterns in males and females [33]. Previous studies have demonstrated the value of ergonomic training and tools in reducing musculoskeletal discomfort in laptop computer users [34]. Training can increase the number and frequency of breaks taken and also encourage improvedpostures.

Discomfort intensity was not captured in this survey, which may make it difficult to make comparisons between individuals or between males and females. In addition, the results do not present a full picture of discomfit due to this omission. Future work should include a measure of intensity in order to make more precise comparisons between groups.

There are also other variables that could impact comfort when using a laptop, such as the size of the device. It has been shown that smaller devices are generally associated with higher levels of postural deviation [18]. These variables were not controlled or accounted for in this study due to its limitedscope.

6 Conclusion

This study investigated sex differences in musculoskeletal discomfort and the configurations of laptop use that are most popular for college students and provides direction for future studies in terms of postures and configurations. A sex difference in specific locations of musculoskeletal discomfort was found, but not in total discomfort. The mechanism behind this finding is unclear, although there are several possibilities, such as differences in usage patterns or differences in skeletal size between the sexes that warrant further investigation. A sex difference in usage configurations was also found in this study, which may be a contributing factor to the different patterns of discomfort between groups, although further work is needed to determine the nature of the relationship. This study offers insights into patterns of laptop use in college students that can be used to inform future work on the impact of technology use on discomfort.

Conflict of interest

The authors have no conflict of interest to report.

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