Exoskeletons and Occupational Health Equity

Posted on by Lakshmi D. Robertson, DrPH, MSPH; Laura Syron, PhD, MPH; Michael Flynn, MA; Ted Teske, MA; Hongwei Hsiao, PhD; Jack Lu, PhD, CPE; and Brian D. Lowe, PhD, CPE

 

In the workplace, you need your equipment to fit perfectly. Historically, personal protective equipment (PPE) had been developed from measurements taken from male military recruits in the United States during the 1950s to the 1970s [1]. These data do not represent the range of body shapes and sizes in the majority of the modern workforce, as they are based on men who were young, fit, and the majority of whom were white. This has resulted in poorly fitting PPE for women, non-whites, and individuals with body shapes and sizes that may not fall ‘within the range’, i.e. those who are overweight, shorter than 5’5ʺ or taller than 6’. As more women enter occupations such as construction, manufacturing, and logistics management improperly fitting PPE is an especially major challenge [2]. Poorly fitting PPE is particularly problematic because it can prevent equipment from functioning properly, be a safety hazard, and discourage its use by workers [3].

To promote health equity in the workplace, the future design of PPE and technology must account for a wider range of human shapes and sizes to ensure accessibility for all workers. Health equity is when everyone has the opportunity to be as healthy as possible [4]. An example of how health equity can be applied in the workplace is in the emerging area of occupational exoskeletons. Occupational exoskeletons are “wearable devices that augment, enable, assist, and/or enhance physical activity through mechanical interaction with the body.” [5]. They are designed to physically assist workers in reducing their exposure to associated physical demands [6]. There are two major types of exoskeletons: active or powered exoskeletons, which operate by means of electric motors or batteries; and passive or unpowered exoskeletons, which are propelled by human movement [7].

Occupational exoskeleton technologies are rapidly developing and so is the body of evidence regarding their potential effects on workers in diverse applications [8]. It is imperative to assess the critical dimensions and configurations of exoskeletons to make them applicable to and effective for use in a wide range of tasks and to ensure fit, comfort, and usability for a broad set of users of different sizes and body types, genders, and ages [8]. The fit of an exoskeleton is a complex issue. Static assessments of fit that result in a ‘one-size-fits-all’ suit are insufficient [9,10]. Comfortable fitting exoskeleton suits that are adaptable to a variety of body shapes require multivariate or 3-dimensional anthropometric data in the design process [9,10].

Occupational exoskeletons have the potential to reduce the number and associated costs of musculoskeletal injuries in several industries. The use of back assist exoskeletons was found to reduce back muscle activity by 10-44% during handling tasks in laboratory studies [11]. In addition to a reduction in spinal muscle activity, reductions in hip extensor muscle activity by 24%, and neck muscles by 50% were also observed when using a back assist-exoskeleton in laboratory-based tasks [12]. However, the potential benefits of the exoskeleton depend on the posture adopted, the tasks it is used for, and whether it properly fits the user or not [13]. Also, while the benefits are indeed promising, there is the possibility of introducing new risk factors. For example, studies have shown increased chest pressure [13] due to wearing the device.

Many exoskeletons may be designed as ‘unisex’ devices, especially with respect to placement of the exoskeleton components, which may pose a problem to women [10]. Women make up half of the workforce, and any exoskeleton that is designed to fit the entire workforce must fit the female form. Women work in industries and occupations that present many ergonomic hazards and risks for musculoskeletal injuries/illnesses. In 2018, women made up 10% of construction workers, 29% of manufacturing workers, 46% of public administration workers, and 45% of retail workers [14]. Women make up more than 85% of nurse practitioners, registered nurses, licensed practical and vocational nurses, and nursing, psychiatric, and home health aides [14, 15]. Women experience osteoporosis up to four times more than men, 30% of women will have the disease at any given time, and half of women may experience a fracture of the hip, wrist, or vertebrae in their lifetime [16]. In combat, women were injured at more than six-times the rate of their male counterparts, with a significantly higher percentage of these injuries attributable to tasks requiring movement under load [17, 18].

While exoskeletons may be available in more than one size, sizing is only one element of comfort and user acceptance. Back support exoskeletons often have chest pads that may not be comfortable for female employees, and may have proportions between the shoulder width, torso length, and hip width that may be more suited towards male employees [7], leading to poor comfort and low acceptance by women. Poor fitting exoskeleton suits can cause awkward working postures and thus, increase the risk of shoulder/back fatigue or disorders [19]. Poor fit can also discourage use by female employees, making the benefits of this technology less accessible to them.

Within the last two decades, NIOSH researchers have produced much research with more inclusive measurements for PPE. This has included a database for firefighters and firefighter apparatus manufacturers to begin updating their designs of seat belts, fire truck cabs, and PPE. This research was based on a groundbreaking anthropometric study conducted on U.S. firefighters, showing the importance of representative sizing [20, 21]. Recent NIOSH research also revealed that truck drivers’ measurement showed significant differences from truck drivers’ measurements 30 years ago, prompting many in the truck manufacturing industry to redesign truck cabs to better support driver safety [20, 22]. Furthermore, NIOSH research on fall-arrest harness sizing provides practical production information for the harness manufacturing industry to formulate cost-effective harness designs and sizing schemes for diverse populations, especially for women and minorities, to provide the required level of protection, productivity, and comfort [1].

Exoskeleton testing typically involves small sample sizes that may not represent the larger user population sample [23]. Similar to NIOSH’s efforts in producing inclusive measurements for PPE, a larger-scale anthropometry survey of exoskeleton users would be beneficial to exoskeleton manufacturers, users, and safety professionals. Alternatively, experts have suggested using simulation and digital human modeling technologies for assessing the interface between the user and exoskeleton and reducing the test and evaluation burden of using human subjects [24, 25, 26].

Over the past few years, occupational exoskeletons have become widely available and rapidly accepted in a wide range of industries. Exoskeletons have many potential benefits, but they may have just as many unintended consequences. If the exoskeleton does not properly fit the worker, then there may be the possibility of increased injuries. Exoskeleton research is evolving at an exceptional pace. The changing demographics of the workforce need to be taken into consideration to ensure that these technologies are inclusive of the workforce’s diversity and equitably benefit and protect all.

If you have used an exoskeleton in your workplace, please provide your input regarding the following questions in the comment section below:

  1. What do you think are some design problems for exoskeletons?
  2. Is everyone in your workplace able to benefit from exoskeletons, regardless of their body shape and size?

 

Lakshmi (Dawn) D. Robertson, Dr.PH, MSPH, ASP, AEP, is an ergonomist in the NIOSH Western States Division.

Laura Syron, PhD, MPH, is an epidemiologist in the NIOSH Western States Division and Assistant Program Coordinator for the Occupational Health Equity Program.

Michael Flynn, MA, is a social scientist in the NIOSH Division of Science Integration and coordinates the Occupational Health Equity Program.

Theodore D. Teske, MA, is a health communication specialist in the NIOSH Western States Division.

Hongwei Hsiao, PhD, is Chief for the Protective Technology Branch in the NIOSH Division of Safety Research.

Ming-Lun (Jack) Lu, PhD, CPE, is a research ergonomist in the NIOSH Division of Field Studies and Engineering and manager of the NIOSH Musculoskeletal Health Cross-Sector Program.

Brian D. Lowe, PhD, CPE, is a research industrial engineer in the NIOSH Division of Field Studies and Engineering.

 

For More Information

Industrial Exoskeletons

Can exoskeletons reduce musculoskeletal disorders in healthcare workers?

Exoskeletons in construction: will they reduce or create hazards?

Occupational Health Equity

The NIOSH Center for Occupational Robotics Research

 

References

  1. Hsiao, H., Friess, M., Bradtmiller, B., & Rohlf, F. J. (2009). Development of sizing structure for fall arrest harness design. Ergonomics52(9), 1128-1143. https://doi.org/10.1080/00140130902919105
  2. American Society of Safety Professionals. 2019. Women and Safety in the modern workplace: Creating a diverse and inclusive workplace can boost safety, productivity, profitability. Retrieved October 30, 2020 from: https://www.assp.org/docs/default-source/default-document-library/assp_women_and_safety_report_0419.pdf?sfvrsn=28
  3. Goldenhar, L.M., Sweeney, M.H. (1996) Tradeswomen’s perspectives on occupational safety: A qualitative investigation. American Journal of Industrial Medicine, 29, 516-520.
  4. Office of Minority Health & Health Equity. (2020, August 14). Health equity. Centers for Disease Control and Prevention. Retrieved September 14, 2020, from https://www.cdc.gov/healthequity/index.html
  5. The American Society for Testing and Materials. (2020). ASTM F3323-20:Standard Terminology for Exoskeletons and Exosuits, ASTM International, West Conshohocken, PA. www.astm.org
  6. de Looze, M. P., Bosch, T., Krause, F., Stadler, K. S., & O’Sullivan, L. W. (2015). Exoskeletons for industrial application and their potential effects on physical work load. Ergonomics, 59(5), 671–681. https://doi.org/10.1080/00140139.2015.1081988
  7. Marinov, B. (2015, August 19). Types and classifications of exoskeletons. Exoskeleton Report. Retrieved May 1, 2020 from https://exoskeletonreport.com/2015/08/types‐andclassifications‐of‐exoskeletons/
  8. Nussbaum, M. A., Lowe, B. D., De Looze, M., Harris-Adamson, C., & Smets, M. (2019). An introduction to the special issue on occupational exoskeletons. IISE Transactions on Occupational Ergonomics and Human Factors, 7(3-4), 153-162. https://doi.org/10.1080/24725838.2019.1709695
  9. Proceedings of the 2018 Ergo-X symposium: Exoskeletons in the workplace – assessing safety, usability, and productivity, October 1, 2018, Philadelphia, Pennsylvania. (2019). https://doi.org/10.26616/nioshpub2020102
  10. Haning, S. L., & Schwerha, D. J. (2019). Women and Exoskeletons: Design and its Effect on Fit and Comfort. Proceedings of the XXXIst Annual International Occupational Ergonomics and Safety Conference, 067-072.
  11. Frost, D. M., Abdoli, E. M., & Stevenson, J. M. (2009). PLAD (personal lift assistive device) stiffness affects the lumbar flexion/extension moment and the posterior chain EMG during symmetrical lifting tasks. Journal of Electromyography and Kinesiology, 19(6), e403–412. https://doi.org/10.1016/j.jelekin.2008.12.002
  12. Bosch, T., van Eck, J., Knitel, K., & de Looze, M. (2016). The effects of a passive exoskeleton on muscle activity, discomfort and endurance time in forward bending work. Applied Ergonomics, 54, 212–217. https://doi.org/10.1016/j.apergo.2015.12.003
  13. Theurel, J. & Desbrosses, K. (2019). Occupational exoskeletons: overview of their benefits and limitations in preventing work-related musculoskeletal disorders. IISE Transactions on Occupational Ergonomics and Human Factors, 7(3-4), 264-280. https://doi.org/10.1080/24725838.2019.1638331
  14. Bureau of Labor Statistics. (2018). Employed persons by detailed industry, sex, race, and Hispanic or Latino ethnicity. Retrieved July 7, 2020 from https://www.bls.gov/cps/cpsaat18.htm
  15. Department of Labor. (2015). Most Common Occupations for Women. Retrieved July 7, 2020 from https://www.dol.gov/agencies/wb/data/employment-earnings-occupations
  16. Mcclure, S. K., Adams, J. E., & Dahm, D. L. (2005). Common Musculoskeletal Disorders in Women. Mayo Clinic Proceedings, 80(6), 796-802. https://doi.org/10.4065/80.6.796
  17. Donnelly, E. (2016). Marine Corps Force Integration Plan Summary. Center for Military Readiness Senate Armed Services Committee, 1-8. Retrieved July 7, 2020 from http://cmrlink.org/data/sites/85/CMRDocuments/ExecSummDonnellySASCStatement_020216.pdf
  18. O’Leary, T. J., Saunders, S. C., McGuire, S. J., & Izard, R. M. (2018). Sex differences in neuromuscular fatigability in response to load carriage in the field in British army recruits. Journal of Science and Medicine in Sport, 21(6), 591-595. https://doi.org/10.1016/j.jsams.2017.10.018
  19. Baltrusch, S. J., Van Dieën, J. H., Van Bennekom, C. A., & Houdijk, H. (2018). The effect of a passive trunk exoskeleton on functional performance in healthy individuals. Applied Ergonomics, 72, 94-106. https://doi.org/10.1016/j.apergo.2018.04.007
  20. Hsiao, H. (2015, September 16). One size does not fit all. NIOSH Science Blog. Retrieved September 12, 2020, from https://blogs.cdc.gov/niosh-science-blog/2015/09/16/anthropometry/
  21. Guan, J., Hsiao, H., Bradtmiller, B., Kau, T., Reed, M. R., Jahns, S. K., Loczi, J., Hardee, H. L., & Piamonte, D. P. (2012). U.S. truck driver anthropometric study and multivariate anthropometric models for cab designs. Human Factors: The Journal of the Human Factors and Ergonomics Society54(5), 849-871. https://doi.org/10.1177/0018720812442685
  22. Hsiao, H., Friess, M., Bradtmiller, B., & Rohlf, F. J. (2009). Development of sizing structure for fall arrest harness design. Ergonomics52(9), 1128-1143. https://doi.org/10.1080/00140130902919105
  23. Gorgey, A. S. (2018). Robotic exoskeletons: The current pros and cons. World Journal of Orthopedics, 9(9), 112-119. https://doi.org/10.5312/wjo.v9.i9.112
  24. Zingman, A., Earnest, G.S., Lowe, B.D., Branche, C.M. (2017, June 15). Exoskeletons in construction: will they reduce or create hazards? NIOSH Science Blog Retrieved May 17, 2020 from https://blogs.cdc.gov/niosh-science-blog/2017/06/15/exoskeletons-in-construction/
  25. Constantinescu, C., Rus. R., Rusu, C.A., & Popescu, D. (2019). Digital twins of exoskeleton-centered workplaces: challenges and development methodology. Procedia Manufacturing, 39, 58-65. https://doi.org/10.1016/j.promfg.2020.01.228
  26. Pu, S., Chang, J., Pei, Y., Kuo, C., & Wang, M. (2016). Anthropometry-based structural design of a hand exoskeleton for rehabilitation. Retrieved June 26, 2020 from https://ieeexplore.ieee.org/document/7827282
Posted on by Lakshmi D. Robertson, DrPH, MSPH; Laura Syron, PhD, MPH; Michael Flynn, MA; Ted Teske, MA; Hongwei Hsiao, PhD; Jack Lu, PhD, CPE; and Brian D. Lowe, PhD, CPE

7 comments on “Exoskeletons and Occupational Health Equity”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    1. What do you think are some design problems for exoskeletons?
    One current gap in the technology is the ability to cross-compare between like exoskeleton makes and models through uniform offload or torque settings. Human subject testing showing percentage of muscle activation reduction is only as good as you know what the exoskeleton offload settings are so that you can recreate the previous experiments. Having that information is also useful for customers to know appropriate settings to use for different sizes/shapes of individuals and the activities they do.

    2. Is everyone in your workplace able to benefit from exoskeletons, regardless of their body shape and size?
    To an extent, a majority are able to be accommodated by exoskeleton size settings, except in the extreme ranges of really small or really large individuals (both in lengths and circumferences). One recommendation to help with this is to not only have common anthropometry data sets for exoskeleton designers, but also common anthropometry accommodation calculators that can allow multi-variate sizing estimates where the exoskeletons might have adjustment points, such as at the waist, arms, legs, or torso.. This is also very useful for customers, so that they can make sure they are purchasing appropriate exoskeletons that will accommodate the majority of their worker populations. Exoskeleton anthropometry standards adopted by the exoskeleton industry designers and customers (end users) should help reduce these concerns.

    Thank you for your comment.

    What do you think are some design problems for exoskeletons?
    Powered exo’s usually have a much lower number of DOFs than humans. The reduction of DOFs might cause the use of the lower legs and upper legs for regular tasks to be awkward.
    Is everyone in your workplace able to benefit from exoskeletons, regardless of their body shape and size?
    No, I am too tall for our exoskeleton. We are working on accommodating the 95th percentile according tot the ‘Measure of men and women’ book.

    Thank you for your comment.

    I’m curious to know how wearing an exoskeleton affects body width or breadth. For someone who is already considered broad, as in the upper body or shoulders, are existing aisles, doorways, stairs or openings sufficient for safe ingress and egress? For lower extremity exoskeletons, are ramps safer than stairs (similar to ADA building codes) especially in an emergency situation? Should some ADA guidelines apply as best practice? Can the exo be doffed or donned with within a safe time frame or is it safer to keep it on during egress? Will body type affect this ability?

    A note: modern anthropomorphic data is available but costs money. At least one outfit that has current measurements using 3D scan technology from across the globe that can be used for both static and dynamic fit testing has reached out to the Exoskeleton Report asking how can their models reach exoskeleton developers? This data costs money, first to acquire, then to have staff that can validate it, interpret, and design and manufacture changes to the wearables.

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Page last reviewed: December 14, 2020
Page last updated: December 14, 2020