Maaike A. Huysmans

Should office workers spend fewer hours at their computer? A systematic review of the literature

Worldwide, millions of office workers use a computer. Reports of adverse health effects due to computer use have received considerable media attention. This systematic review summarises the evidence for a relationship between the duration of work time spent using the computer and the incidence of hand–arm and neck–shoulder symptoms and disorders. Several databases were systematically searched up to 6 November 2005. Two reviewers independently selected articles that presented a risk estimate for the duration of computer use, included an outcome measure related to hand–arm or neck–shoulder symptoms or disorders, and had a longitudinal study design. The strength of the evidence was based on methodological quality and consistency of the results. Nine relevant articles were identified, of which six were rated as high quality. Moderate evidence was concluded for a positive association between the duration of mouse use and hand–arm symptoms. For this association, indications for a dose–response relationship were found. Risk estimates were in general stronger for the hand–arm region than for the neck–shoulder region, and stronger for mouse use than for total computer use and keyboard use. A pathophysiological model focusing on the overuse of muscles during computer use supports these differences. Future studies are needed to improve our understanding of safe levels of computer use by measuring the duration of computer use in a more objective way, differentiating between total computer use, mouse use and keyboard use, attaining sufficient exposure contrast, and collecting data on disability caused by symptoms.

Software-recorded and self-reported duration of computer use in relation to the onset of severe arm–wrist–hand pain and neck–shoulder pain

Objectives In both science and media, the adverse effects of a long duration of computer use at work on musculoskeletal health have long been debated. Until recently, the duration of computer use was mainly measured by self-reports, and studies using more objective measures, such as software-recorded computer duration, were lacking. The objective of this study was to examine the association between duration of computer use at work, measured with software and self-reports, and the onset of severe arm–wrist–hand and neck–shoulder symptoms. Methods A 2-year follow-up study was conducted between 2004 and 2006 among 1951 office workers in The Netherlands. Self-reported computer duration and other risk factors were collected at baseline and at 1-year follow-up. Computer use at work was recorded continuously with computer software for 1009 participants. Outcome questionnaires were obtained at baseline and every 3 months during follow-up. Cases were identified based on the transition within 3 months of no or minor symptoms to severe symptoms. Results Self-reported duration of computer use was positively associated with the onset of both arm–wrist–hand (RR 1.9, 95% CI 1.1 to 3.1 for more than 4 h/day of total computer use at work) and neck–shoulder symptoms (RR 1.5, 95% CI 1.1 to 2.0 for more than 4 h/day of mouse use at work). The recorded duration of computer use did not show any statistically significant association with the outcomes. Conclusions In the present study, no association was found between the software-recorded duration of computer use at work and the onset of severe arm–wrist–hand and neck–shoulder symptoms using an exposure window of 3 months. In contrast, a positive association was found between the self-reported duration of computer use at work and the onset of severe arm–wrist–hand and neck–shoulder symptoms. The different findings for recorded and self-reported computer duration could not be explained satisfactorily.

Observed differences in upper extremity forces, muscle efforts, postures, velocities and accelerations across computer activities in a field study of office workers

This study, a part of the PRedicting Occupational biomechanics in OFfice workers (PROOF) study, investigated whether there are differences in field-measured forces, muscle efforts, postures, velocities and accelerations across computer activities. These parameters were measured continuously for 120 office workers performing their own work for two hours each. There were differences in nearly all forces, muscle efforts, postures, velocities and accelerations across keyboard, mouse and idle activities. Keyboard activities showed a 50% increase in the median right trapezius muscle effort when compared to mouse activities. Median shoulder rotation changed from 25 degrees internal rotation during keyboard use to 15 degrees external rotation during mouse use. Only keyboard use was associated with median ulnar deviations greater than 5 degrees. Idle activities led to the greatest variability observed in all muscle efforts and postures measured. In future studies, measurements of computer activities could be used to provide information on the physical exposures experienced during computer use. Practitioner Summary: Computer users may develop musculoskeletal disorders due to their force, muscle effort, posture and wrist velocity and acceleration exposures during computer use. We report that many physical exposures are different across computer activities. This information may be used to estimate physical exposures based on patterns of computer activities over time.

Interventions to reduce sedentary behavior and increase physical activity during productive work: a systematic review

OBJECTIVE This review addresses the effectiveness of workplace interventions that are implemented during productive work and are intended to change workers` SB and/or PA. METHODS We searched Scopus for articles published from 1992 until 12 March 2015. Relevant studies were evaluated using the Quality Assessment Tool for Quantitative Studies and summarized in a best-evidence synthesis. Primary outcomes were SB and PA, both at work and overall (ie, during the whole day); work performance and health-related parameters were secondary outcomes. RESULTS The review included 40 studies describing 41 interventions organized into three categories: alternative workstations (20), interventions promoting stair use (11), and personalized behavioral interventions (10). Alternative workstations were found to decrease overall SB (strong evidence; even for treadmills separately); interventions promoting stair use were found to increase PA at work while personalized behavioral interventions increased overall PA (both with moderate evidence). There was moderate evidence to show alternative workstations influenced neither hemodynamics nor cardiorespiratory fitness and personalized behavioral interventions did not influence anthropometric measures. Evidence was either insufficient or conflicting for intervention effects on work performance and lipid and metabolic profiles. CONCLUSIONS Current evidence suggests that some of the reviewed workplace interventions that are compatible with productive work indeed have positive effects on SB or PA at work. In addition, some of the interventions were found to influence overall SB or PA positively. Putative long-term effects remain to be established.

The effects of workplace stressors on muscle activity in the neck-shoulder and forearm muscles during computer work: a systematic review and meta-analysis

Workplace stressors have been indicated to play a role in the development of neck and upper extremity pain possibly through an increase of sustained (low-level) muscle activity. The aim of this review was to study the effects of workplace stressors on muscle activity in the neck-shoulder and forearm muscles. An additional aim was to find out whether the muscles of the neck-shoulder and the forearm are affected differently by different types of workplace stressors. A systematic literature search was conducted on studies investigating the relation between simulated or realistic workplace stressors and neck-shoulder and forearm muscle activity. For studies meeting the inclusion criteria, a risk of bias assessment was performed and data were extracted for synthesis. Results were pooled when possible and otherwise described. Twenty-eight articles met the inclusion criteria, reporting data of 25 different studies. Except for one field study, all included studies were laboratory studies. Data of 19 articles could be included in the meta-analysis and revealed a statistically significant, medium increase in neck-shoulder and forearm muscle activity as a result of workplace stressors. In subgroup analyses, we found an equal effect of different stressor types (i.e. cognitive/emotional stress, work pace, and precision) on muscle activity in both body regions. In conclusion, simulated workplace stressors result in an increase in neck-shoulder and forearm muscle activity. No indications were found that different types of stressors affect these body regions differently. These conclusions are fully based on laboratory studies, since field studies on this topic are currently lacking.

The effect of over-commitment and reward on trapezius muscle activity and shoulder, head, neck, and torso postures during computer use in the field

BACKGROUND Because of reported associations of psychosocial factors and computer related musculoskeletal symptoms, we investigated the effects of a workplace psychosocial factor, reward, in the presence of over-commitment, on trapezius muscle activity and shoulder, head, neck, and torso postures during computer use. METHODS We measured 120 office workers across four groups (lowest/highest reward/over-commitment), performing their own computer work at their own workstations over a 2-hr period. RESULTS Median trapezius muscle activity (P = 0.04) and median neck flexion (P = 0.03) were largest for participants reporting simultaneously low reward and high over-commitment. No differences were observed for other muscle activities or postures. CONCLUSIONS These data suggest that the interaction of reward and over-commitment can affect upper extremity muscle activity and postures during computer use in the real work environment. This finding aligns with the hypothesized biomechanical pathway connecting workplace psychosocial factors and musculoskeletal symptoms of the neck and shoulder.

Effects of four types of non-obtrusive feedback on computer behaviour, task performance and comfort.

This study investigated the effects of non-obtrusive feedback on continuous lifted hand/finger behaviour, task performance and comfort. In an experiment with 24 participants the effects of two visual and two tactile feedback signals were compared to a no-feedback condition in a computer task. Results from the objective measures showed that all types of feedback were equally effective to reduce lifted hand/finger behaviour (effectiveness) compared to absence of feedback, while task performance was not affected (efficiency). In contrast to objective measures, subjective user experience was significantly different for the four types of feedback signals. Continuous tactile feedback appeared to be the best signal; not only the effectiveness and efficiency were rated reasonable, it also scored best on perceived match between signal and required action. This study shows the importance of including user experiences when investigating usability of feedback signals. Non-obtrusive feedback embedded in products and environments may successfully be used to support office workers to adopt healthy, productive and comfortable working behaviour.

Position sense acuity of the upper extremity and tracking performance in subjects with non-specific neck and upper extremity pain and healthy controls

OBJECTIVE We aimed to investigate whether position sense acuity of the upper extremity and tracking performance, pen pressure and muscle activity in a tracking task are affected in subjects with neck and upper extremity pain. METHODS Twenty-three subjects with neck and upper extremity pain and 26 healthy controls participated in the study. Position sense acuity of the upper extremity was measured while subjects pointed at targets, without vision of their arm and hand. In the computer tracking task, subjects were instructed to position a cursor within a moving target dot, using a pen on a tablet. RESULTS Position sense acuity of the upper extremity was impaired in subjects with pain. Their variable error was 20-30% larger than in healthy controls. Subjects with pain also showed reduced tracking precision. Both the mean and the standard deviation of the distance to target were significantly larger in subjects with pain than in healthy controls, 10% and 13% respectively. No differences between groups were found in pen pressure and muscle activity during tracking. CONCLUSION The results suggest that subjects with pain are limited in performing precision tasks due to impaired position sense of the upper extremity, but do not compensate with increased effort.

Grip force control in patients with neck and upper extremity pain and healthy controls

OBJECTIVE To investigate whether sensory and motor problems in patients with non-specific neck and upper extremity pain can be ascribed to a deficit of sensory-motor integration. METHODS Grip force control and adaptation were measured in 81 cases, 32 former cases and 39 healthy controls, during repetitive lifting and holding of an object. The object (300 g) was lifted vertically over 20 cm and held for 5s, using the dominant arm (the affected arm in all cases). The object was novel to the subjects when lifted for the first time, and was lifted five times consecutively. Grip forces orthogonal to the objects surface and its vertical acceleration were measured. RESULTS Cases used significantly higher grip forces than both other groups, while vertical acceleration was not different. After the initial lift, all groups significantly reduced the maximum grip force. CONCLUSIONS Subjects with neck and upper extremity pain consistently use higher grip forces than controls, but adjust grip forces by a similar amount after the first lift. Compensation of impaired sensory information rather than a general deficit in sensory-motor integration seems to account for these findings. SIGNIFICANCE Non-specific neck and upper extremity pain coincides with objectifiable changes in control of grip force.

The effect of overcommitment and reward on muscle activity, posture, and forces in the arm-wrist-hand region--a field study among computer workers.

OBJECTIVE Office workers with high levels of overcommitment and low levels of reward are thought to be more prone to arm-wrist-hand symptoms, possibly through a higher internal physical exposure. The aim of this study was to examine the effects of high overcommitment and low reward on (i) forearm muscle activity, (ii) wrist posture and kinematics, and (iii) forces applied to computer input devices during computer work in an actual work setting. METHODS We continuously measured wrist extensor muscle activity, wrist posture and kinematics, and forces applied to the keyboard and mouse for two hours during the daily work of 120 office workers with four different levels of overcommitment and reward (low-high, high-high, low-low, and high-low). RESULTS Wrist velocities and accelerations in radial-ulnar direction were higher for workers with high compared to low overcommitment, while their wrist range of motion was similar, possibly indicating a higher work pace. Wrist extensor muscle activity and forces applied to the keyboard and mouse were not increased by high overcommitment and/or low reward. CONCLUSION Overall, our findings provide little support for the proposed pathway of high overcommitment and low reward in the development of arm-wrist-hand symptoms through a higher internal physical exposure.