Survey of physical ergonomics issues associated with school childrens’ use of laptop computers

Abstract

The survey investigated the use of laptop computers by children aged 10 to 17 yr at schools in Western Australia. Data collected included general participant information (e.g. age, height); locations and postures adopted for laptop use; time on task and consequences of both using and carrying laptops. 251 participants used the internet to complete the survey and 63 completed written surveys. Twenty participants were interviewed and observed using their laptops in various locations. The mean times for minimum and maximum periods of laptop use at one sitting ranged from 11.5–101.9 min. Mean daily use (3.2 h) and weekly use (16.9 h) was also shown to be high. Postures used by laptop users varied according to location, e.g. home, school and boarding house. Reported consequences of laptop use included technical faults, service and location limitations, hardware and software limitations, user limitations and physical consequences to the user. Sixty percent of students reported discomfort with laptop use and 61% of participants reported discomfort with carrying their laptop. Associations between school attended or year level with time on task and discomfort reports were evident.

Relevance to industry

The use of laptop computers is increasing, both in educational settings and other industries. There is however minimal research on the physical consequences of laptop use by adults or children, and therefore recommendations for using laptop computers are tentative.

Introduction

The use of information technology in all areas of life is rapidly increasing, and this is particularly evident within the school system. Australia is pioneering the use of laptop computers within the school environment, particularly within the private education system. Additionally, laptop computers are one of the fastest growing trends in the world of business today (Steelcase, 1997) and currently the single largest growth area within the personal computer market (Harbison and Forrester, 1995).

Educational literature on the use of laptop computers by school children has been favourable with many benefits being promoted. The attraction to use this type of computer is due to their size and thus portability. A portable computer allows for a greater flexibility of learning environments, greater access to information throughout the learning process, is reported to be fun and provides the opportunity for students to be independent cooperative learners (Shears, 1995; McDonald, 1995).

At present however community based therapists are reporting an increase in the number of students requiring treatment for musculoskeletal injuries and discomfort (Wilson, 1997). This increase in the number of students as patients has been suggested to be related to students’ increased use of computers.

When reviewing the literature there is minimal research reported on the use of laptop computers and the physical implications of their use, both within school and general environments. At the time of this research only four published studies were found that discussed the physical implications of using laptop computers (Diederich and Stewart, 1997; Harbison and Forrester, 1995; Price and Dowell, 1998; Straker et al., 1997a).

The physical implications for the use of desktop computers are well documented. These implications may be able to be generalised to the use of laptop computers, for example in regards to static postures utilised, screen viewing distances and angles, screen height, upper limb and neck postures. However as laptop computers are designed differently the implications of their use will also be different from desktop computer use.

It is generally thought that to minimise discomfort during computer use workers should change postures frequently. Such postural changes are best supported by adjustability within the work station (Jacobs and Bettencourt, 1995). Adjustable work stations also allow for the anthropometric variability between individuals using work stations (Straker et al., 1997a). An adjustable computer work station can therefore contribute to a range of suitable working postures for the user. Therefore a work station that is not adjustable (without adjustable screen height and distance) is not recommended for prolonged use (Diederich and Stewart, 1997).

The work station for a desktop computer user should be adjustable by having at least an independent keyboard and screen and well designed furniture. Research suggests that computer work stations that promote awkward or constrained body postures predispose the user towards musculoskeletal injury, and that persistent musculoskeletal problems relate to poor work station design and adjustability (Harbison and Forrester, 1995).

As laptop computers generally have their screens fixed to the keyboard, there is not the adjustability in the work station that is expected and recommended in a desktop computer work station. The laptop user can adjust their viewing angle, however independent adjustment of the screen and keyboard distance and height cannot be made if external equipment is not utilised. The height and distance of the screen impacts on the users’ head and neck posture and the height and distance of the keyboard probably affects neck, shoulder, arm and trunk posture. This can therefore lead to the laptop user assuming an awkward posture to operate the laptop computer.

Straker et al. (1997a) suggest that a laptop user would assume a posture for use that would compromise their typing posture either by increased neck flexion in order to see a lower screen; and/or by increased shoulder and elbow flexion, to reach a higher keyboard. This is further supported by Harbison and Forrester (1995), who found that laptop users required an increased forward head inclination to adequately operate the computer due to its lack of adjustability.

The forward head inclination posture adopted by all laptop user subjects in Harbison and Forrester's (1995) study, was more than 30° greater than the recommended neck posture as outlined in Australian Standard 3590.2 (1990). The mean head inclination angle ranged from 44.0° to 49.6° depending on the location of use. In contrast to this ergonomists have stated that the head and neck should not be bent forward by more than 15° otherwise fatigue will be experienced (Grandjean, 1987), although this is debated (Straker, 2000b).

It is therefore proposed that the laptop user is likely to assume an awkward, constrained posture when typing due to the design of the laptop. From our knowledge of awkward postures with desktop use we can predict that laptop users could therefore experience musculoskeletal discomfort and problems with laptop use (Price and Dowell, 1998). Laptop user problems could occur from awkward postures but also, like desktop user problems, could occur from the length of time these postures are maintained.

Kroemer (1989, p. 279) recommends that to avoid cumulative trauma disorders a person should not maintain a body posture for “long periods of time”. This is well recognised in the literature in order to prevent static loading of muscles and therefore muscle fatigue, impaired circulation and a pain-spasm cycle (Carter and Banister, 1994). However the phrase “for long periods” is not quantified. Research alternatively discusses this issue by suggesting that a computer user should take frequent breaks, vary their seated posture throughout the work day and/or be able to rotate their work stations to adopt different work postures at different work stations (Carter and Banister, 1994). The length of time recommended to use the computer for in one sitting or posture type is not quantified.

Straker et al.'s (1997a) study on postures assumed for laptop and desktop computers demonstrated that after twenty minutes all participants reported some areas of discomfort, e.g. pain, headaches and muscle fatigue, mainly in the neck and upper back.

The detrimental effects on performance and the users’ health by a small change in posture have been documented by Straker et al. (1997b), in their study on shoulder postures with typing tasks. Their study demonstrated that after 20 min of typing participants with zero degrees shoulder flexion performed better on the task and had less discomfort and fatigue than those subjects using 30° of shoulder flexion for typing.

Based on these studies, postures assumed for periods of time greater than just 20 min could lead to musculoskeletal problems for the user.

Therefore the type of postures utilised for laptop computer use, and the length of time these postures are maintained, could lead to adverse effects on the user's health, satisfaction and performance.

As minimal information was available on these issues generally, and especially with regard to school children, the aim of this study was to investigate the use of laptop computers by school children. In particular, the study investigated the postures adopted for laptop use, the length of time laptops were used, and reports of problems with laptop use.