Sedentary work has come to dominate

Transcription

1 feature Stand Up and Move; Your Musculoskeletal Health Depends on It An examination of dynamic workstations shows some physical benefits, but often at the expense of productivity. By Kermit G. Davis & Susan E. Kotowski FEATURE AT A GLANCE: The new trend in office ergonomics is installing dynamic workstations that include sit-to-stand tables, treadmills, stationary bicycles, and exercise balls. The question is whether it is worth the investment to try to reduce musculoskeletal pain via these dynamic workstations. Postural change is good, but the most effective workstation seems to be the sit-to-stand table with respect to reducing discomfort suffered by office workers. Treadmills and cycle workstations do have the ability to increase energy expenditure and heart rate and thus are potentially beneficial in addressing obesity that results from sedentary work. For all outcomes, the key is to periodically get up and move around. KEYWORDS: office ergonomics, workstation, musculoskeletal disorders, physical ergonomics, low back, physiology Sedentary work has come to dominate work in the modern society, whether it is traditional secretarial work, the recent infusion of call centers for telemarketing in the service sector, or different types of design (e.g., graphic, AutoCAD, computer programming). Computers, other technological advances, and, sometimes, incentive pay for productivity have contributed to sedentary work by encouraging workers to forego rest and meal breaks. Telemarketers spend long hours answering phones and entering information into the computer. Call center operators spend more than 80% of their time at work in a seated position (Rocha, Glina, Marinho, & Nakasato, 2005; Toomingas, Forsman, Mathiassen, Heiden, & Nilsson, 2012). Designers utilize sophisticated computer software that provides the flexibility as well as digital drawing capabilities that allow for the development of state-of-the-art products, graphics, or even floor plans. The tedious nature of design requires lots of detailed mouse clicks with fine resolution, resulting in long durations of static seated postures. Sedentary work has been linked to several adverse disorders and disabilities, such as obesity, diabetes, and cardiovascular disease (MacEwen, MacDonald, & Burr, 2015; Wilmot et al., 2012). Musculoskeletal disorders have also been linked to sedentary work, specifically those of the hand and wrist, neck, upper back, and low back (Ekman, Andersson, Hagberg, & Heljm, 2000; Gerr et al., 2002; Korhenon et al., 2003; Rocha et al., 2005; Wahlström, 2005; Wahlström, Hagberg, Toomingas, & Tornqvist, 2004). The pain and discomfort from these injuries and disorders has translated into a 10% to 20% drop in productivity (Hagberg, Tornqvist, & Toomingas, 2002). In short, remaining in a seated position for long durations results in high frequencies of pain and discomfort. Recent studies have investigated office interventions for sedentary workers (MacEwen et al., 2015; Torbeyns, Bailey, Bos, & Meeusen, 2014), including dynamic workstations that encourage postural movement and even walking while working. As a result of introducing dynamic movement, office work environments have started to look more like workout facilities than offices, with treadmills, stationary bicycles, and exercise ball chairs built into the workstations. Is this trend of new dynamic workstations a passing fad or an effective intervention to sedentary office work? We discuss the evidence of several dynamic workstation options for their potential to effectively reduce the adverse effects of sedentary work. Sit-to-Stand Workstations: Effective Dynamic Workstations or Expensive Static Desks? The concept of the sit-to-stand workstation is that workers can alternate between sitting and standing at any time by raising the work surface to a standing height and lowering it to a sitting height. By changing from a sedentary, seated position to a standing position, the worker changes posture, exerting large muscle groups in the legs and trunk that pump blood throughout the musculoskeletal system. The actual energy expenditure change is minimal, but use of both sitting- and standing-height workstations enables the worker to continue 9

2 to perform the job requirements without significant detriment to productivity (Davis & Kotowski, 2014). The keys to proper use of the sit-to-stand workstation are as follows: (a) desktop height is adjusted properly when in both sitting and standing position, where the monitor is slightly below eye level (Hedge, Jagdeo, Argawal, & Rockey-Harris, 2005); (b) at seated height, the chair is properly adjusted; (c) keyboard and mouse are in a position where both maintain good working postures (e.g., no reaching with arms or twisting of trunk); and (d) a work culture is developed that encourages, through training, adjustment throughout the day (Robertson, Ciriello, & Garabet, 2013). Overall, sit-to-stand workstations, when actively switched between seated and standing heights, routinely are effective in reducing discomfort in the upper and lower back (Davis & Kotowski, 2014; Karakolis & Callaghan, 2014; MacEwen et al., 2015). Davis and Kotowski (2014) found that switching every 30 min was sufficient to reduce discomfort without negatively affecting productivity (e.g., keystrokes, mouse clicks, and phone calls). Karakolis and Callaghan (2014), in their review, found no conclusive results as to the best ratio of sitting to standing, although they noted that more frequent switches resulted in decreases in productivity. This review also provided other evidence of the benefits of sit-to-stand workstations, such as less spinal shrinkage (e.g., less disc height reduction) and foot swelling. Compliance with the sit-stand paradigm is clearly a significantly influential factor in whether these types of workstations are effective in reducing musculoskeletal pain. In all likelihood, there is a limited impact on the well-being and potential for body weight reduction using the sit-to-stand paradigm, as workers will typically have limited movement in the standing position (e.g., mostly standing and limited walking). However, research that could contribute to a conclusive decision on this type of outcome is lacking (MacEwen et al., 2015); specifically, no research has been conducted to identify what is the best proportion of sitting and standing time when using the sit-to-stand workstation. Take-home message. Sit-to-stand workstations can be effective in reducing musculoskeletal discomfort without any deficit in productivity (Davis & Kotowski, 2014; Karakolis & Callaghan, 2014; MacEwen et al., 2015), but success depends on the culture instituted in the workplace; workers must be diligent about changing heights throughout the day over the long term. However, companies must understand that the verdict is still out on whether these workstations can effectively reduce musculoskeletal disorders and not merely discomfort. Additionally, more research is needed to identify the optimal switching schedules to maximize postural change, productivity, and health. Treadmill Workstations: Walking Fad or Trend Setter? The treadmill workstation can be found in two formats, pure standing workstation and sit-to-stand workstation. In both cases, a treadmill is attached to the workstation so that the worker can walk directly in front of the monitor and keyboard. For the standing workstation, the treadmill is typically centered in the workstation, whereas the sit-to-standstyle workstation will have the treadmill offset so that the chair can be on one side and the treadmill on the other side. The concept for treadmill workstations is that the worker will walk while working on the computer at a slow and steady pace. Recommended speed of the treadmill is 1 to 2 mph due to a potential risk of falling and detriments to cognitive processing (MacEwen et al., 2015) and self-selected pacing (Thompson & Levine, 2011). One of the major concerns for the treadmill workstation is the dual demands on the human system: mental processing required for computer processing tasks and other office work that occurs simultaneous with walking. A concern for companies when implementing treadmill workstations is the potential for falls. Another concern with the treadmill workstation is decreased productivity for keyboard and mouse entry, which likely results from the additional psychological processing of the dual demands (MacEwen et al., 2015). Evidence on the impact of treadmill workstations on office workers is strong with respect to increasing physiological responses, such as heart rate and energy expenditure (MacEwen et al., 2015; Torbeyns et al., 2014). Some additional benefits have been found with respect to decreases in body weight and waist circumference, but the evidence is weak; few researchers have investigated these types of outcomes (Torbeyns et al., 2014). In theory, walking while working throughout the day will increase caloric expenditure, resulting in reduced weight over time, if all other conditions are kept the same. On the other hand, the effectiveness of treadmills in reducing musculoskeletal pain is unknown (Torbeyns et al., 2014). Take-home message. Treadmill workstations have increased in visibility but appear better equipped to reduce adverse effects of excessive weight than to improve musculoskeletal health. Compared with other types of workstations, there is an increased risk for falls with a treadmill workstation. Cycling Workstations: Are They an Upright Treadmill Workstation in Disguise? Cycling workstations are similar to treadmill workstations in that a unique piece of equipment is attached to the workstation. A modified stationary bike is positioned in front of a workstation, often with an adjustable-height work surface so the worker can ride the bike with plenty of knee clearance and use the keyboard, mouse, and monitor. Some concerns with 10 ergonomics in design July 2015

3 Figure 1. Example of exercise ball workstations. Note: These products were chosen as a sample representative of the types of workstations and are not endorsed by the authors. this type of dynamic workstation are (a) lack of support for the back for long-term cycling, (b) dual demands of cycling and computer processing, and (c) making sure the workstation is properly adjusted to cycle-person height. Similar to the treadmill workstation, the cycle workstation increases physical activity during the day (Elmer & Martin, 2014) as well as typical physiological responses, such as heart rate and energy expenditure (Botter et al., 2013; Elmer & Martin, 2014). Authors of a few studies have also reported decreases in productivity for cycle workstations (Torbeyns et al., 2014). However, the effectiveness of cycle workstations is still unknown; only a few researchers have investigated this workstation type, and none has evaluated musculoskeletal discomfort or pain as an outcome. Take-home message. Cycling workstations provide a similar impact on physiological responses, such as energy expenditure and heart rate, compared with a treadmill, but there is insufficient evidence about the impact on worker discomfort. There are also concerns with productivity (e.g., typing and mouse activity) for workers using the cycle workstation. Exercise Ball Workstations: Dynamic Stabilizer or Fancy Bouncy Seat? Whether the exercise ball is used alone or in one of a number of different types of frames, its purpose as an alternative workstation seat is that it will allow greater postural variation and continuous activation of the muscles in the torso (see Figure 1). The premise is that discomfort associated with prolonged sitting postures would be reduced as a result of the increase in body movement and muscle activation. Although little research exists on the exercise ball as an alternative seating option, the few existing studies show mixed outcomes in terms of differences in muscle activity between an exercise ball and a more traditional chair but increased discomfort with the exercise ball (Gregory, Dunk, & Callaghan, 2006; Kingma & van Dieen, 2009; McGill, Kavcic, & Harvey, 2006). Gregory et al. (2006) found no significant differences in participants average muscle activity between an office chair and exercise ball, except for one muscle, when performing various computer tasks. However, they did find that participants reported significantly greater discomfort ratings overall and for the low back when using the exercise ball. On the other hand, Kingma and van Dieen (2009) found average muscle activity increases exceeding 35%, coupled with an increase of over 65% in trunk motion, when workers used an exercise ball while performing a typing task. Discomfort was not measured in this study, and the impact of increased trunk movement on the spine is not clear. Similar to Gregory et al., McGill and colleagues (2006) found no difference in muscle activity between sitting on an exercise ball and a wooden stool but did find trends of increased spinal stability and compression. In all three of these studies, testing time was kept to 30 min to 1 hour per condition, limiting the ability to understand long-term impacts. No research has been carried out on the impact on productivity when using an exercise ball as an alternative seating option, nor has there been any research on the physiological impact of continuous use of an exercise ball as an office workstation seat. Take-home message. Exercise ball workstations seemingly produce muscle activity similar to that of a more traditional workstation chair but at higher levels of discomfort. The impact this alternative has on productivity is unknown. Break Reminders: Look, No Equipment Needed Another way to introduce postural variation into the office workplace is to implement a break policy that requires the worker to step away from the workstation periodically throughout the day, ideally every 20 to 30 min. Traditional breaks two 15 min and one 30 min are not sufficient to minimize discomfort at the end of the work shift (Galinsky et al., 2007). Routine rest breaks have been found to be effective in controlling musculoskeletal discomfort of the neck and shoulder for computer work (Goodman et al., 2012; Hoe, Urquhart, Kelsall, & Sim, 2012; Kennedy et al., 2010). Other researchers have also confirmed that more frequent and routine breaks can improve discomfort without adversely 11

4 affecting productivity (Dababneh, Swanson, & Shell, 2001; Henning, Jacques, Kissel, Sullivan, & Alteras-Webb, 1997). In a recent study by Davis and Kotowski (2014), computergenerated reminders at 30-min intervals proved to be an effective method to encourage movement and breaks throughout the day, which resulted in lower discomfort in the shoulders, upper back, and lower back. The interesting result for this study was the fact that the workers spent 20% more time away from the workstation with no drop in productivity an actual 10% increase in phone calls, keystrokes on keyboards, and mouse clicks (not significant, though) was observed. These breaks were often less than 60 s, indicating that breaks can be short and still be effective. Some researchers have also shown the effectiveness of reminder software to encourage breaks and reduce adverse musculoskeletal outcomes without affecting productivity (Bernaards, Ariëns, Simons, Knol, & Hildebrandt, 2008; Dababneh et al., 2001). Reminders of breaks can be utilized very effectively even with a sit-to-stand workstation to further decrease adverse musculoskeletal outcomes (Davis & Kotowski, 2014). There has been no research on the impact of rest breaks on physiological and weight-related measures. Conceptually, the alternative would likely have limited impact on these types of outcomes unless the breaks included significant walking or other physical activity. Take-home message. Routine rest breaks throughout the day can effectively reduce musculoskeletal discomfort without affecting productivity, unlike the types of dynamic workstations discussed here. Breaks should be taken more often than 15 min in the morning and afternoon and a lunch break halfway through the shift, as this schedule does not provide enough rest and still allows significant sedentary periods. Power of Postural Variability The results of the scientific studies noted here indicate that postural changes whether they result from adjusting a sit-to-stand workstation or routine breaks may reduce musculoskeletal discomfort (although this is not conclusive) without affecting productivity. Dynamic workstations, such as treadmill or cycling workstations, can be effective in increasing energy expenditure but at a detriment to productivity. The key to better worker health and well-being is encouraging routine movement around the office. Simple actions, such as rearranging the printer relative to the workstation so the worker has to stand up to get the printout, utilizing a reminder to take routine breaks and get out of one s seat, and going over to talk to a person instead of talking on the phone, will encourage movement while still allowing workers to use their time productively. At the end of the day, having a culture that encourages breaks will be more successful in reducing symptoms of musculoskeletal discomfort for workers. Then, everyone can return home pain-free. References Bernaards, C. M., Ariëns, G. A., Simons, M., Knol, D. L., & Hildebrandt, V. H. (2008). Improving work style behavior in computer workers with neck and upper limb symptoms. Journal of Occupational Rehabilitation, 18, Blatter, B. M., & Bongers, P. M. (2002). Duration of computer use and mouse use in relation to musculoskeletal disorders of neck or upper limb. International Journal of Industrial Ergonomics, 30, Botter, J., Burford, E. M., Commissaris, D., Könemann, R., Hiemstra-van Mastrigt, S., & Ellegast, R. P. (2013). The biomechanical and physiological effect of two dynamic workstations. In V. G. Duffy (Ed.), Digital human modeling and applications in health, safety, ergonomics, and risk management: Human body modeling and ergonomics (pp ). Berlin, Germany: Springer. Dababneh, A. J., Swanson, N., & Shell, R. L. (2001). Impact of added rest breaks on the productivity and well being of workers. Ergonomics, 44, Davis, K. G., & Kotowski, S. E. (2014). Postural variability: An effective way to reduce musculoskeletal discomfort in office work. Human Factors, 56, Ekman, A., Andersson, A., Hagberg, M., & Heljm, E. W. (2000). Gender differences in musculoskeletal health of computer and mouse users in the Swedish workforce. Occupational Medicine, 50, Elmer, S. J., & Martin, J. C. (2014). A cycling workstation to facilitate physical activity in office settings. Applied Ergonomics, 45, Galinsky, T., Swanson, N., Sauter, S., Dunkin, R., Hurrell, J., & Schleifer, L. (2007). Supplementary breaks and stretching exercises for data entry operators: A follow-up field study. American Journal of Industrial Medicine, 50, Gerr, F., Marcus, M., Ensor, C., Kleinbaum, D., Cohen, S., Edwards, A., Genrty, E., Ortiz, D. J., & Monteilh, C. (2002). A prospective study of computer users: I. Study design and incidence of musculoskeletal symptoms and disorders. American Journal of Industrial Medicine, 41, Goodman, G., Kovach, L., Fisher, A., Elsesser, E., Bobinski, D., & Hansen, J. (2012). Effective interventions for cumulative trauma disorders of the upper extremity in computer users: Practice models based on systematic review. Work: A Journal of Prevention, Assessment and Rehabilitation, 42, Gregory, D. E., Dunk, N. M., & Callaghan, J. P. (2006). Stability ball versus office chair: Comparison of muscle activation and lumbar spine posture during prolonged sitting. Human Factors, 48, Hagberg, M., Tornqvist, E. W., & Toomingas, A. (2002). Self-reported reduced productivity due to musculoskeletal symptoms: Associations with workplace and individual factors among white-collar computer users. Journal of Occupational Rehabilitation, 12, Hedge, A., Jagdeo, J., Argawal, A., & Rockey-Harris, K. (2005). Sitting or standing for computer work does a negative-tilt keyboard tray make a difference? In Proceedings of the Human Factors and Ergonomics Society 49th Annual Meeting (pp ). Santa Monica, CA: Human Factors and Ergonomics Society. Henning, R. A., Jacques, P., Kissel, G. V., Sullivan, A. B., & Alteras-Webb, S. M. (1997). Frequent short rest breaks from computer work: Effects on productivity and well-being at two field sites. Ergonomics, 40, Hoe, V. C., Urquhart, D. M., Kelsall, H. L., & Sim, M. R. (2012). Ergonomic design and training for preventing work-related musculoskeletal disorders of the upper limb and neck in adults. Cochrane Database of Systematic Reviews, 8, CD Karakolis, T., & Callaghan, J. P. (2014). The impact of sit stand office workstations on worker discomfort and productivity: A review. Applied Ergonomics, 45, Kennedy, C. A., Amick, B. C., III, Dennerlein, J. T., Brewer, S., Catli, S., Williams, R., Serra, C., Gerr, F., Irvin, E., Mahood, Q., Franzblau, A., van Eard, D., Evanoff, B., & Rempel, D. (2010). Systematic review of the role of occupational health and safety interventions in the prevention of upper extremity musculoskeletal symptoms, signs, disorders, injuries, claims and lost time. Journal of Occupational Rehabilitation, 20, Kingma, I., & van Dieen, J. H. (2009). Static and dynamic postural loadings during computer work in females: Sitting on an office chair versus sitting on an exercise ball. Applied Ergonomics, 40, Korhenon, T., Ketol, R., Toivonen, R., Luukkoenen, R., Häkkänen, M., & Viikari-Junura, E. (2003). Work related and individual predictors for incident neck pain among office employees working with video display units. Occupational and Environmental Medicine, 60, ergonomics in design July 2015

5 MacEwen, B. T., MacDonald, D. J., & Burr, J. F. (2015). A systematic review of standing and treadmill desks in the workplace. Preventive Medicine, 70, McGill, S. M., Kavcic, N. S., & Harvey, E. (2006). Sitting on a chair or an exercise ball: Various perspectives to guide decision making. Clinical Biomechanics, 21, Robertson, M. M., Ciriello, V. M., & Garabet, A. M. (2013). Office ergonomics training and a sit-stand workstation: Effects on musculoskeletal and visual symptoms and performance of office workers. Applied Ergonomics, 44, Rocha, L. E., Glina, D. M. R., Marinho, M. D. F., & Nakasato, D. (2005). Risk factors for musculoskeletal symptoms among call center operations of a bank in Sao Paula, Brazil. Industrial Health, 43, Thompson, W. G., & Levine, J. A. (2011). Productivity of transcriptionists using a treadmill desk. Work, 40, Toomingas, A., Forsman, M., Mathiassen, S. E., Heiden, M., & Nilsson, T. (2012). Variation between seated and standing/walking postures among male and female call centre operators. BMC Public Health, 12. Retrieved from Torbeyns, T., Bailey, S., Bos, I., & Meeusen, R. (2014). Active workstations to fight sedentary behaviour. Sports Medicine, 44, Wahlström, J. (2005). Ergonomics, musculoskeletal disorders and computer work. Occupational Medicine, 55, Wahlström, J., Hagberg, M., Toomingas, A., & Tornqvist, E. W. (2004). Perceived muscular tension, job strain, physical exposure and associations with neck pain among VDU users: A prospective cohort study. Occupational and Environmental Medicine, 61, Wilmot, E. G., Edwardson, C. L., Achana, F. A., Davies, M. J., Gorely, T., Gray, L. J., Khunti, K., Yates, T., & Biddle, S. J. H. (2012). Sedentary time in adults and the association with diabetes, cardiovascular disease and death: Systematic review and meta-analysis. Diabetologia, 55, Kermit G. Davis is an associate professor at the University of Cincinnati in the College of Medicine, Department of Environmental Health, where he also directs the Low Back Biomechanics and Workplace Stress Laboratory. He received his PhD in occupational ergonomics from The Ohio State University College of Engineering, Department of Industrial and Systems Engineering. He is a Certified Professional Ergonomist. Susan E. Kotowski is an assistant professor at the University of Cincinnati in the College of Allied Health Sciences. She is also director of the Gait and Movement Analysis Lab. She received her PhD in occupational ergonomics and safety from the University of Cincinnati, College of Medicine. She is a Certified Professional Ergonomist. Copyright 2015 by Human Factors and Ergonomics Society. All rights reserved. DOI: /