Posted to CDC.gov on June 15, 2017 by Alissa Zingman, MD; G. Scott Earnest, PhD, PE, CSP; Brian D. Lowe, PhD, CPE; Christine M. Branche, Ph.D., FACE;
Wearable exoskeleton devices can reduce some of the mechanical stress of manual labor (1). These wearable machines can be powered by electricity or by human motion, and they can be as large as a space suit or as small as a glove. (1; 2) They are used to amplify or transform worker movements, improve biomechanics and efficiency, and are increasingly prevalent in the public and private sectors. NIOSH published its first blog on this topic in 2016 (3). As these devices are deployed more widely in the workplace, sound research is required to assess potential dangers and benefits of this new technology.
Construction is a physically demanding, labor-intensive industry with heavy manual material handling and awkward work postures. Musculoskeletal disorders (MSDs) are a leading cause of injury among construction workers (4; 5), with overexertion in lifting causing over one-third of these injuries. (6) The rate of work-related musculoskeletal disorders in construction is 16% higher than in all industries combined(5). Since back injuries are the most prevalent work-related musculoskeletal disorders in construction, (5) and shoulder and other joint injuries are also major causes of injury, exoskeletons present an attractive possibility.
In a study of forward bend lifting using an exoskeleton designed to decrease load to the spine and improve posture, researchers found that exoskeletons decrease total work, fatigue and load while improving posture. (1) This is supported by additional studies (1; 7). In addition to decreasing load on the spine, exoskeletons have been shown to decrease shoulder discomfort while increasing productivity and work quality among painters and welders (8).
While these benefits are promising, exoskeletons also introduce new risk factors. The same study also demonstrated increased chest pressure due to wearing the device.(1) This could negatively impact workers, particularly those with pre-existing conditions, such as chronic obstructive pulmonary disease (COPD). There are other potential risks to exoskeleton use. The weight of devices designed for extending reach could result in inadvertent increased load to the spine. Poor fit could cause pressure wounds or compressed nerves. Lack of hygienic practices for devices used by multiple users could spread infectious diseases.
Some exoskeletons are unwieldy or cumbersome and may limit users mobility including the ability to move out of the way of a falling object. They also could shift the user’s center of gravity causing such problems and diminished recovery strategy, the human body’s response to loss of balance. Data shows that human recovery strategy following a collision was negatively impacted by use of an exoskeleton.(9) This is particularly important in the construction industry, where working in close quarters and at heights are common., In addition, human factors related to the introduction of a wearable device, such as decreased vigilance or distraction from other safety measures, could also impact safety. These workplace complexities must be addressed with high-quality research to identify hazards, address risk reduction, and develop guidelines for use and best practices.
There are relatively few studies concerning use of exoskeletons in construction to reduce risk factors of load handling. Some field trials have been conducted in Europe. Preliminary results of a recent study in France (10) suggest that a device designed to provide overhead load assistance to the user had the adverse effect of creating additional effort to counteract resistance when the arms moved beyond the intended range. Another French study (11) found that exoskeleton users were able to operate an overhead tool using less force and that users reported “certain types of pain disappeared.” However, this seemed to be a highly specialized task, involving skilled and technical application of plaster, and it is not clear how broadly the preliminary study can be interpreted. Both reports highlighted the importance of considering how the exoskeleton is adapted to the specific work task and the acquired skills of the user.
Much of the research and progress in the U.S. that is relevant to exoskeleton usage in industry and rehabilitation has been supported by the U.S. Department of Defense. (12) The U.S. military, collaborating with the National Center for Manufacturing Sciences, evaluated exoskeleton use in naval shipyard industrial settings. Naval shipyard workers lift heavy hand-held tools and supplies, work in awkward postures, and work at various heights as in construction. A study of the industrial human augmentation system (iHAS), an integrated system composed of two different exoskeletons (13) found that use of the iHAS was associated with an approximately ten percent increase in productivity, a reduction in vibration of the hands, and improved quality of work (14)(12).
Exoskeletons have the potential to enhance worker productivity, provide assistance to aging workers, and decrease the risk of musculoskeletal disorders. The U.S. National Institute for Standards and Technology (NIST) has examined the need for standards and test methods related to the use of exoskeletons. (15) In Europe, a 2015 European Union (EU) research and development project set out to develop “standards for the safety of exoskeletons used by industrial workers performing manual handling activities.” (16) The effort involved creating an exoskeleton hazard database to describe potential hazards throughout the exoskeleton’s lifecycle; identifying strategies to mitigate and reduce risks; and creating systems to test exoskeleton design concepts for their ability to perform tasks safely. The intent of this effort is to develop policies and standards for exoskeleton use in industry. Currently, there is insufficient data to determine complete safety profiles or health effects for long-term use of exoskeletons. Future research, is needed to develop appropriate standards before construction workers are exposed to the potential hazards associated with their use.
If you have used an exoskeleton in your workplace, tell us about your experience in the comment section below.
Alissa Zingman, MD, Occupational and Environmental Medicine Resident, Johns Hopkins Hospital, Johns Hopkins School of Medicine and Johns Hopkins Bloomberg School of Public Health, on rotation at NIOSH [February 2017].
Scott Earnest, PhD, PE, CSP; Deputy Director for the NIOSH Office of Construction Safety and Health, Coordinator for the Construction Sector.
Brian D. Lowe, PhD, CPE; Research Industrial Engineer in the NIOSH Division of Applied Research and Technology.
Christine Branche, PhD, FACE; Principal Associate Director and Director, NIOSH Office of Construction Safety and Health.
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(2) Bosch, T., van Eck J., Knitel, K., de Looze, M. The effects of a passive exoskeleton on muscle activity, discomfort and endurance time in forward bending work. Appl Ergon. May 2016, 54:212-7.
(3) Lowe, B., Dick, RB, Hudock, S., Bobick, T. Wearable Exoskeletons to Reduce Physical Load at Work. NIOSH Science Blog. March 4, 2016.
(4) Waehrer, GM, Dong, X.S., Miller, T., Men, Y., Haile, E. Occupational Injury Costs and Alternative Employment in Construction Trades. JOEM. 2007, 49(11):1218-27.
(5) CPWR. The Construction Chartbook. Fifth Ed. CPWR- the Center for Construction Research and Training. Silver Spring, MD. April 2013.
(6) O’Sullivan, L., Nugent R., van der Vorm, J. Standards for the safety of exoskeletons used by industrial workers performing manual handling activities: A contribution from the Robo-Mate project to their future development. Procedia Manufacturing. 2015, (3):1418-25.
(7) Da Costa BR, Vieira, ER. Risk factors for work-related musculoskeletal disorders: a systematic review of recent longitudinal studies, American Journal of Industrial Medicine. 2010, 53(3):285-323.
(8) Butler, T. Exoskeleton Technology: Making workers safer and more productive. Prof Safety. Sept. 2016.
(9) Schiffman, J., Gregorczyk, K., Bensel, C., Hasselquist, L., Obusek, J. The effects of a lower body exoskeleton load carriage assistive device on limits of stability and postural sway, Ergonomics, Taylor & Francis, 2008, 51, 1515-1529.
(10) Froment, N. The use of exoskeletons on construction sites. Innovorg – Technical Innovation and Organisational Changes Conference, 2017. Nancy, France.
(11) Atain-Kouadio, J.J., Wioland, L., Theurel, J., and Delacourt, A. Integrating an exoskeleton: feedback and reference points. Innovorg – Technical Innovation and Organisational Changes Conference, 2017. Nancy, France.
(12) Bender, J. The military is closing in on powerful exoskeleton technology. The Business Insider. August 18, 2014
(13) NCMS (2016) Industrial Human Augmentation Systems (iHAS) for Improved Shipyard Operations: Final Report. National Center for Manufacturing Sciences. Ann Arbor, MI, May 2016.
(14) Waitt, T. Fortis Exoskeleton Improves U.S. Navy Shipyard Ops. American Security Today. Feb 26, 2017.
(16) Federici S, Meloni, F, Bracalenti, M, De Filippis, ML. The effectiveness of powered, active lower limb exoskeletons in neurorehabilitation: A systematic review. NeuroRehabilitation. 2015, 37(3):321-40.