Exoskeletons used in the workplace are referred to as “industrial exoskeletons.” Their purpose is to augment, amplify, or reinforce the performance of a worker’s existing body components—primarily the lower back and the upper extremity (arms and shoulders). Despite a lack of research, manufacturers of these devices claim productivity gains, work quality improvements, and a reduction of the risk of work‐related musculoskeletal disorders (WMSDs). A new commentary from NIOSH in the American Journal of Industrial Medicine highlights some of the potential benefits and risks of industrial exoskeletons. The article cautions that before widespread implementation of industrial exoskeletons occurs, research is needed to evaluate the effectiveness of exoskeletons across various industry sectors.[1]

In the United States, the economic impact of WMSDs is increasing rapidly. WMSDs accounted for an aggregate economic impact of $367.1 billion in 1996, and $796.3 billion in 2009‐2011, an increase of 117%.[2],[3]. If exoskeletons achieved reductions in the mechanical stressors associated with manual materials handling tasks, they would have the potential to reduce high rates of WMSDs seen in many industries.

There are two major types of industrial exoskeletons.[4] An “active” exoskeleton can be powered through actuators such as electric motors, pneumatics, hydraulics, or a combination of these technologies, and is often referred to as a “robotic exoskeleton.” Natural human movement powers a “passive” exoskeleton through springs and counterbalance forces. Most commercially available industrial exoskeletons can be grouped into the following categories: (a) back assist, (b) shoulder and arm assist, (c) tool holding/support, and (d) leg assist.[5] Back assist exoskeletons are used primarily to provide general support for the lumbar spine, to maintain a correct posture, and to assist during lifting or static holding tasks.[6] Shoulder assist and supernumerary (nonanthropomorphic) arm tool holding support exoskeletons are used to support the upper extremities during sustained overhead work or to assist in holding heavy tools.[7] Leg assist devices provide support to the hip, knee, or ankle joint in simple movement or while carrying a load,[8],[9] or serve as an alternative to a chair for relief from standing for long periods of time.[10]

Wearable exoskeleton devices may be beneficial in reducing musculoskeletal loads that are not otherwise reduced by changes in engineering processes.[11],[12] They may then lead to the reduction of the WMSD symptoms and, possibly, WMSD incidence rates. However, most studies to date have involved only small numbers of participants (many studies with less than 15 participants) in laboratory settings, which makes it more difficult to draw firm conclusions about the benefits of industrial exoskeletons despite the expectations about their role in injury prevention.[7, 13-20] The research to date identifies the following potential benefits and risks related to the use of exoskeletons in the workplace.

Potential Benefits

Low-back exoskeletons

• Dynamic lifting using a passive exoskeleton designed to decrease the load to the spine and improve posture found that exoskeletons decreased muscle activity and reduced spinal muscle loading, resulting in a decrease in overall spinal muscle fatigue.[6, 13]
• Static trunk bending reduced muscle activity and spinal loading.[6]
• A wearable exoskeleton has been designed to help construction workers to work in more neutral postures to reduce low‐back strain.[21]

Upper Extremity Exoskeletons

• Studies have shown that upper extremity exoskeletons may have a role in reducing shoulder WMSDs. Shoulder assist exoskeletons have been shown to decrease shoulder discomfort while increasing productivity and work quality among painters and welders.[22]
• Decreased deltoid muscle strain has been shown for various types of overhead tasks while using a shoulder assist exoskeleton.[7, 15,23]
• Spinal compressive forces decreased by nearly 20% and shear forces decreased by 30% with the use of exoskeletons.[16]
• When upper extremity exoskeletons are used along with a proactive ergonomics program, such devices may reduce risk factors associated with work‐related shoulder injuries.[24]

Potential Risks

• The U.S. Consumer Product Safety Commission (CPSC) warned that muscle strain could occur if a powered exoskeleton moves beyond the normal range of motion of a user’s joint(s). [25] Wearable devices could cause skin irritation or chemical burns if an exoskeleton battery leaks corrosive materials. If an exoskeleton battery suddenly discharges its stored energy thermal burns would occur.
• One study found use of a heavy tool (13.6 kg) with a vest-mounted stabilizing arm resulted in increased load to the spine.[19] This illustrates the importance of matching an exoskeleton system appropriately to the task characteristics.
• In one study, upper‐extremity exoskeleton devices did not reduce the total load on the worker, but rather shifted the load from the shoulders to the lower back and legs.[7]
• Other risks include pressure wounds or compressed nerves from prolonged use.
• In trials in the construction industry, worker have raised concerns about hygiene.[26] When devices are used by multiple uses, poor hygiene could spread infectious diseases particularly in warmer climates.[27]
• Some exoskeletons are unwieldy or cumbersome and may limit the user’s overall mobility, including the ability to avoid collision with a moving object.
• Some exoskeletons can significantly shift the user’s center of gravity causing balance problems and lessen the user’s ability to recover from losing their balance.[27]
• There is the potential for over‐reliance on exoskeleton technology. Exoskeletons use should be limited to addressing residual risks – risks that cannot be feasibly eliminated through engineering controls.
• Transference of risk is an additional consideration. If an exoskeleton increases the amount of a time a worker can hold a tool, this could increase other exposures occurring at the same time for long periods such as hand‐transmitted vibration,[28] noise, and exposure to respirable toxins.

This blog touches on the major points regarding the future of exoskeleton use in the workplace. A more in-depth discussion can be found in the article. Before the widespread implementation of industrial exoskeletons occurs, research is needed to evaluate the effectiveness of exoskeletons in reducing the risk factors for WMSDs associated with various industrial work across different industry sectors. The occupational safety and health research community and those implementing the use of exoskeletons in the workplace should work together to develop a research strategy to fill current safety and health knowledge gaps, understanding the benefits, risks, and barriers to adoption of industrial exoskeletons. It is also critical to determine whether exoskeletons can be considered a type of personal protective equipment and work together to advance consensus standards that address exoskeleton safety.

NIOSH, along with several other Federal agencies, participates on ASTM Committee F48 on Exoskeletons and Exosuits. This standards development committee is addressing potential risks through a number of standards activities. The topics that are active or in development include: safety considerations in designing and selecting exoskeletons; system training; load handling when using an exoskeleton; recording environmental conditions for utilization with exoskeleton test methods; labeling and information for exoskeletons and exosuits; and wear, care, and maintenance instructions.

NIOSH is planning several research projects, including (1) assessing the effects of back assist exoskeletons in manual materials handling in the wholesale and retail trade sector; (2) assessing the longitudinal health effects of passive shoulder exoskeletons in the manufacturing sector, (3) evaluating safety hazards potentially associated with exoskeletons while working on elevated surfaces in the construction sector, (4) examining the feasibility of using exoskeletons for safe patient handling in the healthcare sector, (5) exploring the application of exoskeletons in the mining industry; and (6) evaluating exoskeleton systems for reducing hand-transmitted vibration.

If you have used or contemplated using exoskeletons in your workplace please provide input on the following questions in the comment section below the blog post (click here to visit the blog post on the NIOSH website and leave a comment):

1. What has been your experience in using exoskeletons for industrial work?
2. What kinds of barriers have you faced in adopting exoskeletons in your workplace?
3. What issues or concerns would you like to see addressed by consensus standards for industrial exoskeletons?

References

[1] Goldenhar LM, LaMontagne AD, Katz T, Heaney C, Landsbergis P. The intervention research process in occupational safety and health: an overview from the National Institute for Occupational Safety and Health intervention effectiveness research team. J Occup Environ Med. 2001;43(7):616‐622. https://www.ncbi.nlm.nih.gov/pubmed/11464392

[2] American Academy of Orthopaedic Surgeons. U.S. Bone and Joint Initiative. The Burden of Musculoskeletal Diseases in the United States. 3rd Ed. Rosemont, Illinois: U.S. Bone and Joint Initiative; 2016. https://www.boneandjointburden.org/docs/The%20Burden%20of%20Musculoskeletal%20Diseases%20in%20the%20United%20States%20(BMUS)%203rd%20Edition%20(Dated%2012.31.16).pdf

[3] Yelin E, Weinstein S, King T. The burden of musculoskeletal diseases in the United States. Semin Arthritis Rheu. 2016;46(3):259‐260. https://doi.org/10.1016/j.semarthrit.2016.07.013

[4] Bostelman R, Messina E, Foufou S. Cross‐industry standard test method developments: from manufacturing to wearable robots. Front Inform Technol Electron Eng. 2017;18(10):1447‐1457.

[5] Marinov B. Types and classifications of exoskeletons. Exoskeleton Report. 2015. https://exoskeletonreport.com/2015/08/types‐andclassifications‐of‐exoskeletons/. Accessed September 1, 2019.

[6] de Looze MP, Bosch T, Krause F, Stadler KS, O’Sullivan LW. Exoskeletons for industrial application and their potential effects on physical work load. Ergonomics. 2015;59(5):671‐681.

[7] Rashedi E, Kim S, Nussbaum MA, Agnew MJ. Ergonomic evaluation of a wearable assistive device for overhead work. Ergonomics. 2014; 57(12):1864‐1874. https://doi.org/10.1080/00140139.2014.952682

[8] Zoss AB, Kazerooni H, Chu A. Biomechanical design of the Berkeley lower extremity exoskeleton (BLEEX). IEEE/ASME Transactions on Mechatronics. 2006;11(2):128‐138. https://ieeexplore.ieee.org/document/1618670

[9] Kim W, Lee H, Kim D, Han J, Han C. Mechanical design of the Hanyang exoskeleton assistive robot (HEXAR). 14th International Conference on Control, Automation and Systems (ICCAS 2014). https://ieeexplore.ieee.org/document/6988049. Accessed October 31, 2019.

[10] Luger T, Cobb TJ, Seibt R, Rieger MA, Steinhilber B. Subjective evaluation of a passive lower‐limb industrial exoskeleton used during simulated assembly. IISE Trans Occup Ergonomics Hum Factors. 2019:1‐10. https://doi.org/10.1080/24725838.2018.1560376

[11] Lowe BD, Dick RB, Hudock S, Bobick T. Wearable exoskeletons to reduce physical load at work. NIOSH Science Blog. 2016. https://blogs. cdc.gov/niosh‐science‐blog/2016/03/04/exoskeletons/. Accessed on September 1, 2019.

[12] Lowe B, Billotte WG, Peterson DR. ASTM F48 formation and standards for industrial exoskeletons and exosuits. IISE Trans Occup Ergonomics Hum Factors. 2019:1‐7. https://doi.org/10.1080/24725838.2019.1579769

[13] 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. 2016;54:212‐217. https://doi.org/10.1016/j.apergo.2015.12.003

[14] Theurel J, Desbrosses K, Roux T, Savescu A. Physiological consequences of using an upper limb exoskeleton during manual handling tasks. Appl Ergon. 2018;67:211‐217. https://doi.org/10.1016/j.apergo.2017.10.008

[15] Kim S, Nussbaum MA, Esfahani MIM, Alemi MM, Alabdulkarim S,Rashedi E. Assessing the influence of a passive, upper extremity exoskeletal vest for tasks requiring arm elevation: Part I—“Expected” effects on discomfort, shoulder muscle activity, and work task performance. Appl Ergon. 2018;70:315‐322. https://doi.org/10.1016/j.apergo.2018.02.025

[16] Kim S, Nussbaum MA, Esfahani MIM, Alemi MM, Jia B, Rashedi E. Assessing the influence of a passive, upper extremity exoskeletal vest for tasks requiring arm elevation: Part II—“Unexpected” effects on shoulder motion, balance, and spine loading. Appl Ergon. 2018;70:328‐330. https://doi.org/10.1016/j.apergo.2018.02.024

[17] Baltrusch SJ, van Dieen JH, van Bennekom CAM, Houdijk H. The effects of a passive trunk exoskeleton on functional performance in healthy individuals. Appl Ergon. 2018;72:94‐106. https://doi.org/10.1016/j.apergo.2018.04.007

[18] Huysamen K, Bosch T, de Looze M, Stadler KS, Graf S, O’Sullivan LW. Evaluation of a passive exoskeleton for static upper limb postures. Appl Ergon. 2018;70:148‐155. https://doi.org/10.1016/j.apergo.2018.02.009

[19] Weston EB, Alizadeh M, Knapik GG, Wang X, Marras WS. Biomechanical evaluation of exoskeleton use on loading of the lumbar spine. Appl Ergon. 2018;68:101‐108. https://doi.org/10.1016/j.apergo.2017.11.006

[20] Alabdulkarim S, Nussbaum MA. Influences of different exoskeleton designs and tool mass on physical demands and performance in a simulated overhead drilling task. Appl Ergon. 2019;74:55‐66. https://doi.org/10.1016/j.apergo.2018.08.004

[21] Cho YK, Kim K, Ma S, Ueda J. A robotic wearable exoskeleton for construction worker’s safety and health. Construction Research Congress 2018: Safety and disaster management—Selected papers from the Construction Research Congress, April 19‐28, 2018. https://ascelibrary.org/doi/pdf/10.1061/9780784481288.003. Accessed September 1, 2019.

[22] Butler T. Exoskeleton technology. Making workers safer and more productive. Prof Saf. 2016:32‐36. https://www.pathwaynpi.com/wpcontent/uploads/ASSE_Exoskeleton_Sept‐2016.pdf

[23] Gillette JC, Stephenson ML. EMG analysis of upper body exoskeleton during automotive assembly. 42nd Annual Meeting of the American Society of Biomechanics, Rochester, MN. August 8th‐11th, 2018. https://www.researchgate.net/publication/327187565_EMG_analysis_of_an_upper_body_exoskeleton_during_automotive_assembly. Accessed September 1, 2019.

[24] Smets M. A field evaluation of arm‐support exoskeletons for overhead work applications in automotive assembly. IISE Trans Occup Ergonomics Hum Factors. 2019:1‐7.

[25] Consumer Product Safety Commission. Potential hazards associated with emerging and future technologies. Staff Report, January 18, 2017. https://www.cpsc.gov/s3fs‐public/Report%20on%20Emerging%20Consumer%20Products%20and%20Technologies_FINAL.pdf. Accessed September 1, 2019.

[26] Kim S, Moore A, Srinivasian D, et al. Potential of exoskeleton technologies to enhance safety, health, and performance in construction: industry perspectives and future research directions. IISE Trans Occup Ergonomics Hum Factors, 1‐7. https://doi.org/10.1080/24725838.2018.1561557

[27] Zingman A, Earnest GS, Lowe BD, Branche CM. Exoskeletons in construction: will they reduce or create hazards? NIOSH Science Blog. June 15, 2017. https://blogs.cdc.gov/niosh‐science‐blog/2017/06/15/exoskeletons‐in‐construction/. Accessed September 1, 2019.

[28] McDowell TW, Xu XS,Warren C, Welcom DE, Dong RG. The effects of exoskeleton vests on hand transmitted vibration. Proceedings of the 14th International Conference on Hand‐Arm Vibration, May 21‐24,2019, Bonn, Germany, pp. 69‐70. https://www.dguv.de/medien/ifa/de/vera/2019_hav/hav_2019_abstracts.pdf. Accessed September 1, 2019.