The effect of forearm support on musculoskeletal discomfort during call centre work

Abstract

Using a computer keyboard with the forearms unsupported has been proposed as a causal factor for neck/shoulder and arm/hand diagnoses. Recent laboratory and field studies have demonstrated that forearm support might be preferable to working in the traditional “floating” posture. The aim of this study was to determine whether providing forearm support when using a normal computer workstation would decrease musculoskeletal discomfort in intensive computer users in a call centre.

A randomised controlled study (n=59), of 6 weeks duration was conducted. Thirty participants (Group 1) were allocated to forearm support using the desk surface with the remainder (Group 2) acting as a control group. At 6 weeks, the control group was also set up with forearm support. Both groups were then monitored for another 6 weeks. Questionnaires were used at 1, 6 and 12 weeks to obtain information about discomfort, workstation setup, working posture and comfort.

Nine participants (Group 1 n=6, Group 2 n=3) withdrew within a week of commencing forearm support either due to discomfort or difficulty in maintaining the posture. At 6 weeks, the group using forearm support generated significantly fewer reports of discomfort in the neck and back, although the difference between the groups was not statistically significant. At 12 weeks, there were fewer reports of neck, back and wrist discomfort when preintervention discomfort was compared with post intervention discomfort.

These findings indicate that for the majority of users, forearm support may be preferable to the “floating” posture implicit in current guidelines for computer workstation setup.

Introduction

The relationship between musculoskeletal disorders of the neck and upper extremity in association with computer use has been well documented (Pascarelli and Kella, 1993; Sauter et al., 1991). Risk factors associated with computer use include physical ergonomic factors such as keyboard, chair and monitor heights, working postures (Aaras et al., 1997; Grandjean et al., 1984), organisational factors such as duration of computer use per day and psychosocial factors such as stress (Smith and Carayon, 1996).

Discomfort of the proximal and distal upper extremities has been associated with the use of input devices such as the keyboard (Amell and Kumar, 2000) and mouse (Cook et al., 2000; Fogelman and Brogmus, 1995). Working without arm support has been proposed as one of the causal factors of neck and shoulder and arm hand diagnoses (Maeda, 1977; Erdelyi et al., 1988; Hagberg and Sundelin, 1986; Bergqvist et al., 1995). Despite this, the traditional “floating” posture in which a neutral wrist posture is maintained without supporting the arms is still widely used.

Upper extremity support has been reported to reduce static neck and shoulder muscle load during computer keyboard use (Aaras et al., 1998; Cook and Burgerss-Limerick, 2001; Marcus et al., 2002). Aaras et al. (2001) reported a significant decrease in neck, shoulder and back discomfort in a group of computer users who were able to support their whole forearm and hand on a concave workstation. No decrease in discomfort was reported for the distal upper extremity. In a recent prospective epidemiological study of computer users, Marcus et al. (2002) reported use of the keyboard placed more than 12 cm from the edge of the desk was associated with a lower risk of hand-arm symptoms. In a recent laboratory study, forearm support using a conventional desk was also found to result in significantly less ulnar deviation, less time spent in an extreme wrist posture and fewer reports of discomfort (Cook and Burgerss-Limerick, 2001).

Supporting the forearm on the work surface may decrease discomfort, decrease muscular load of the neck and shoulders and decrease harmful wrist postures, thereby creating a beneficial posture for keyboard and mouse users. However, the benefits of providing arm support during keyboard and mouse use in a conventional workstation have only been previously described in the laboratory setting (Cook and Burgerss-Limerick, 2001).

As the provision of specialised equipment such as concave desks is not always practical due to cost, the effect of adjusting a conventional workstation to allow forearm support during keyboard operation requires evaluation in a field setting.

The aim of this study was to determine whether adjusting a conventional workstation to enable forearm support during computer use decreases reports of neck/shoulder or wrist/hand musculoskeletal discomfort in intensive computer users in a field setting.