Postural load during VDU work: a comparison between various work postures.

The aim of this study was to compare the postural load during VDU work in the following work postures: (1) Supporting and not supporting the forearms on the table top, (2) Sitting and standing positions, and (3) Sightline to the centre of the screen at an angle of 15 degrees and 30 degrees below the horizontal. The muscle load from the upper part of musculus trapezius and from the lumbar part of musculus erector spinae (L3 level) was measured by electromyography (EMG). Postural angles of head, upper arm and back were measured by inclinometers. The load on m. trapezius when using the keyboard was significantly less in sitting with supported forearms compared to sitting and standing without forearm support. Further, the time and number of periods when the trapezius load was below 1% MVC was significantly greater with support versus no support. The load on the right erector spinae lumbalis was also significantly less and the time when the load was below 1% MVC was significantly longer in a sitting work position with support versus standing without support. In addition, when using a mouse supporting the forearms reduced the static trapezius load in sitting. The results from this study document clearly the importance of giving the operator the possibility of supporting the forearms on the table top.

[1]  R. Westgaard,et al.  Postural angles as an indicator of postural load and muscular injury in occupational work situations. , 1988, Ergonomics.

[2]  A. Aarås.  Relationship between trapezius load and the incidence of musculoskeletal illness in the neck and shoulder , 1994 .

[3]  H Heuer,et al.  Vertical Gaze Direction and the Resting Posture of the Eyes , 1989, Perception.

[4]  R H Westgaard,et al.  Pattern of muscle activity during stereotyped work and its relation to muscle pain , 1990, International archives of occupational and environmental health.

[5]  B. Knave,et al.  Work with video display terminals among office employees. I. Subjective symptoms and discomfort. , 1985, Scandinavian journal of work, environment & health.

[6]  M Thoresen,et al.  Musculoskeletal, visual and psychosocial stress in VDU operators before and after multidisciplinary ergonomic interventions. , 1998, Applied ergonomics.

[7]  T Bendix,et al.  Wrist support during typing--a controlled, electromyographic study. , 1986, Applied ergonomics.

[8]  O. Hänninen,et al.  Shoulder strain in keyboard workers and its alleviation by arm supports , 1988, International archives of occupational and environmental health.

[9]  R. Ortengren,et al.  Lumbar disc pressure and myoelectric back muscle activity during sitting. II. Studies on an office chair. , 1976, Scandinavian journal of rehabilitation medicine.

[10]  K. Harms-Ringdahl.  On assessment of shoulder exercise and load-elicited pain in the cervical spine. Biomechanical analysis of load--EMG--methodological studies of pain provoked by extreme position. , 1986, Scandinavian journal of rehabilitation medicine. Supplement.

[11]  Bengt Knave,et al.  A longitudinal study of VDT work and health , 1992, Int. J. Hum. Comput. Interact..

[12]  Toshisada Nishida,et al.  Natural history of a tool-using behavior by wild chimpanzees in feeding upon wood-boring ants , 1982 .

[13]  M. Kenward,et al.  Design and Analysis of Cross-Over Trials , 1989 .

[14]  R. Westgaard,et al.  Electromyographic evaluation of muscular work pattern as a predictor of trapezius myalgia. , 1993, Scandinavian journal of work, environment & health.

[15]  R. Ortengren,et al.  Myoelectric back muscle activity during sitting. , 1974, Scandinavian journal of rehabilitation medicine. Supplement.

[16]  L Philipson,et al.  Muscular load levels in performing musicians as monitored by quantitative electromyography , 1990 .

[17]  G. Elfström,et al.  Lumbar disc pressure and myoelectric back muscle activity during sitting. I. Studies on an experimental chair. , 1974, Scandinavian journal of rehabilitation medicine.

[18]  A Aarås,et al.  Measurement of postural angles during work. , 1988, Ergonomics.

[19]  R Ortengren,et al.  Reproducibility and stability of normalized EMG measurements on musculus trapezius. , 1996, Ergonomics.

[20]  G Parenmark,et al.  Ergonomic on-the-job training of assembly workers. Arm-neck-shoulder complaints drastically reduced amongst beginners. , 1988, Applied ergonomics.

[21]  R. Ortengren,et al.  Myoelectric activity in individual lumbar erector spinae muscles in sitting. A study with surface and wire electrodes. , 1974, Scandinavian journal of rehabilitation medicine. Supplement.

[22]  K. Hansen,et al.  Trapezius muscle load as a risk indicator for occupational shoulder-neck complaints , 1993, International archives of occupational and environmental health.

[23]  Arne Aarås,et al.  Postural load and the incidence of musculoskeletal illness , 1991 .