Exoskeletons – All They Are Purported to Be?

I recently returned from the NEC ErgoExpo in Las Vegas (Vegas in August… whose idea was that??) and was happy to hear the latest science on the application of exoskeletons for use in industry.

Exoskeletons, often referred to as “lift-assists”, are based on actuation technology, designed to transfer away force/torque from the user to the device instead.  There are passive models (best for light tasks and limited dynamic movements) and active models which are more suited for dynamic tasks and have their own pneumatic or electrical power source, but are more rigid, heavier and bulky.¹ This also translates into the passive technologies being less complex and cheaper to implement. However, active models are more versatile and consequently, more costly.

There are also “soft” exoskeletons compared to “hard” versions. The soft are designed to provide better comfort to the worker (an important feature for user acceptance) by being lightweight and reducing movement hindrances.

But can they prevent (insert anatomy here) injuries?

Such technology is often touted as the answer to musculoskeletal disorders (MSDs) and reduction of physical fatigue by their manufacturers. But under scrutiny and scientific rigor, are these devices the solution we’re looking for? The short answer is… it depends.

With the influx of new designs and brands every day, it’s important that you do your homework. That means not relying on the manufacturer’s words and their financially backed studies that may not have been peer-reviewed or evidenced-based.

When I wasn’t loitering at outdoor restaurant misting devices (to cool off) or rehydrating with a mimosa at the trade show (to cool off), I sat in on a session led by Mathew Marino, a specialist in evaluating wearable technologies, and who presented his own findings regarding the use of exoskeletons and their pros and cons.

In a study he conducted in the utility sector, specifically targeting workers responsible for the installation and maintenance of smart meters underground, passive back-assist exoskeletons were used while they performed digging and sustained kneeling/bending/reaching activities. What they found was that the exoskeletons work best in reducing metabolic demands associated with static loading an of the muscles, but they didn’t provide the same advantage in terms of reducing metabolic demands during repetitive motions.

In a different study completed by Mathew Marino², a comparison of passive back-assist and passive shoulder-assist exoskeletons revealed that, depending on the device being used and the task being performed (in this case, stocking and tire installation tasks), heart rate and step rate could be negatively or positively affected. The back assist that he tested actually demonstrated an increase in mean heart rate (6.8%) compared to the shoulder assist (decrease by 3.4%). Both devices had similar reductions in step rates at 17.4 % and 20.5% accordingly. Whether or not these types of reductions correlate to a reduction in MSDs remains to be seen. As pointed out by Marino during his presentation, there are no longitudinal studies, at least none that are currently published, that clearly indicate any such benefit.

Worker Trials

Perhaps more importantly is the feedback from the workers themselves. As with any wearable technology that is introduced, fit and comfort will influence whether or not the employees will want to wear such devices. In the tire installation study, there were concerns regarding how they also impacted the quality of their body movements and potentially, task completion.

So, if you’re looking to add these types of devices to your arsenal, here are a few things to remember:

1. What tasks are you looking for help with? Dynamic tasks require more versatility (active devices). Static or restricted postures will benefit more from passive devices.
2. Determine your targets and how you will measure overall performance impact. Are you looking to reduce injuries? Reduce fatigue? Reduce time spent on task? Improve worker comfort? Be sure that you have completed a thorough risk assessment to determine exactly what your needs are before you start investing in technology that may or may not match.
3. Comfort and fit are imperative. Each device should be fitted to an individual worker, where it remains theirs to own and maintain, similar to a mechanic having his own tools. While these devices are meant to fit many people, they are not always easy to adjust and you are relying on the workers to have the necessary knowledge and training to optimally readjust the equipment with each use. There is also a concern about hygiene when transferring devices between users. Unfortunately, if one is used per worker, it may make them cost-prohibitive.
4. Try before you buy. In fact, try several and implement a system usability scale to measure the end-users perceptions of the devices that you are evaluating before purchase. A google search will bring up plenty of scales that you can modify to suit your needs.

At the end of the day, it’s about eliminating hazards and reducing risk. Undoubtedly, these devices will evolve and become better over time (even Ironman had to work out the kinks) and hopefully, the longitudinal studies will follow, but for now, they are limited in their applications. In the interim, don’t forget that there may be other ways to engineer or redesign the job that reduce risk to acceptable levels. Exoskeleton technology is just one more tool to consider adding to your toolbox. It’s not the only tool.Looking for ergonomics training? Check out our Ergonomics Systems Specialist (ESS) Workshop, a 5-day certification course that provides you with the knowledge on how to establish your own internal ergonomics program while earning you continuing education credits. Learn how to secure management commitment, perform risk assessments, utilize cost/benefit tools, measure performance, and ensure program sustainability.¹

¹Toxiri, Stefano & B. Näf, Matthias & Lazzaroni, Maria & Fernández, Jorge & Sposito, Matteo & Poliero, Tommaso & Monica, Luigi & Anastasi, Sara & G. Caldwell, Darwin & Ortiz, Jesus. (2019). Back-Support Exoskeletons for Occupational Use: An Overview of Technological Advances and Trends. 1-13. 10.1080/24725838.2019.1626303.

²Matthew Marino (2019) Impacts of Using Passive Back Assist and Shoulder Assist Exoskeletons in a Wholesale and Retail Trade Sector Environment, IISE Transactions on Occupational Ergonomics and Human Factors.