Page 44 - Occupational Health & Safety, October 2018

ERGONOMICS
extremity exoskeletons used for sustained, overhead work and/or heavy tool use? Data shows the results are mixed, as well.
Impact on reducing occupational MSDs when wearing an upper- extremity device
There is no peer-reviewed scientific research that has investi- gated or measured the impact that upper-extremity devices have on reducing MSDs. Thus, the potential impact on reducing upper- extremity MSDs is unknown (Rashedi et al., 2014).
However, recent research provides some insights on spinal loading (force experienced by the lower back) while wearing an upper-extremity device. Spinal load is one of the primary risk fac- tors for lower-back pain (Marras, 2012, and NCR, 2001). The peer- reviewed scientific research findings are mixed.
Impact on productivity and work quality
There is little peer-reviewed scientific research on the impact of upper-extremity devices on task performance, including produc- tivity and quality of work. Again, the results are mixed.
Impact on worker stamina and health
There is more peer-reviewed scientific research on the im- pact on worker stamina, including measures of muscle activity (a physiological measurement of effort), muscle fatigue, and per- ceived discomfort.
The impact on muscle activity includes the following:
■ Reduced muscle activity in the shoulder by 36 to 73 percent
(Kim et al., Part I, 2018; Rashedi et al., 2014; Theural et al., 2018) and in the (back of) arm by 40 percent (Rashedi et al., 2014)
■ Increased muscle activity in the (back of) arm by 95 to 116 percent (Theural et al., 2018)
■ Increased low-back muscle activity and demand by 31 to 120 percent (Rashedi et al., 2014; Theural et al., 2018; Weston et al., 2018)
■ Increased abdominal muscle activity by 42 to 66 percent (Weston et al., 2018)
■ Increased (front) lower leg muscle activity (Theural et al., 2018)
It appears that the use of upper-extremity devices is not reduc- ing the load on the human, just shifting the load from the shoulders to the lower back and legs.
Are They Ready for Prime Time?
In simple terms, the potential for industrial exoskeletons to im- prove human performance and possibly reduce MSDs is tremen- dous. Unfortunately, we know little about the physiological benefits and the unexpected consequences. Since there seems to be an equal number of both, the devices are not quite ready for prime time. But we are likely a decade away from a fully functional device that can provide the benefits with few consequences.
Blake McGowan, CPE, is an Ergonomics Engineer and Managing Consultant with Humantech. The full version of this article, including its references, is available at www.ohsonline.com.
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