Women in the Skilled Trades - Exoskeleton Guidelines
Women in the Skilled Trades - Exoskeleton Guidelines
Conducted applied field-to-lab-to-field studies to generate ergonomic guidelines tailored to women workers, aiming to reduce injuries and support recruitment and retention.
Funding: Funded by National Science and Engineering Research Council.
What did this Project Set Out to Do?
This project examined how passive shoulder exoskeletons interact with worker characteristics and task demands during overhead construction work, with particular attention to implications for women in the skilled trades. While exoskeletons are increasingly promoted to reduce shoulder strain, less is known about how their benefits vary by sex, body archetype, posture, and how they influence workers’ perception of acceptable workload and risk tolerance.
The project aimed to develop evidence‑based guidance for the safe and equitable deployment of exoskeletons in construction by investigating both subjective (psychophysical) and objective (muscle activation) responses to overhead tool use with and without exoskeleton assistance.
How was the Research Done?
Two complementary laboratory‑based studies were conducted with construction workers.
Experimental Tasks and Conditions
- Participants performed unilateral overhead drilling tasks at shoulder elevations of 90°, 120°, and 150°
- Tasks were completed with and without a passive shoulder exoskeleton
- Drilling was performed at regular intervals to simulate sustained work demands
Measurement Approaches
- A psychophysical method was used to determine the maximum acceptable drill weight participants felt they could tolerate over a full work shift
- Surface electromyography (EMG) measured muscle activation in key shoulder and upper‑body muscles
- Participant anthropometrics were captured using 3D body scanning, and body archetypes were identified using k‑cluster analysis
- Mixed‑effects statistical models assessed the influence of exoskeleton use, body archetype, sex, shoulder elevation, drill weight, and time
This combined approach allowed the researchers to examine not only how much assistance exoskeletons provide, but whether that assistance meaningfully changes perceived workload and physiological demand.
What did the Project Discover?
The results demonstrated that exoskeleton benefits are real but not uniform, and that worker characteristics play a significant role in outcomes.
Psychophysical Load Selection
- Wearing an exoskeleton increased the maximum acceptable drill weight by approximately 18%
- Females selected lighter loads than males, even with exoskeleton assistance
- Participants with smaller body archetypes selected lower acceptable loads than larger‑built workers
- Shoulder elevation alone did not significantly affect acceptable load selection
Muscle Activation and Load Redistribution
- Exoskeleton use reduced anterior deltoid muscle activation, indicating unloading of primary shoulder elevators
- The increase in middle deltoid activation with heavier loads was attenuated when using the exoskeleton
- At higher shoulder elevations, some load redistribution was observed to posterior shoulder musculature
- Muscle activation patterns differed by body archetype, suggesting morphology‑dependent responses
Together, the findings revealed that while exoskeletons reduce shoulder demand, they may also shift muscular capacity depending on posture, load, and user characteristics.
Why Does This Matter?
As exoskeletons are introduced into construction workplaces, design, task selection, and policy guidance must reflect the diversity of the workforce. For women in the skilled trades, and/or for other workers with smaller body builds, equipment that increases acceptable load without fully accounting for muscular demand may introduce new risks if not deployed thoughtfully.
This project provides foundational evidence to support:
- Inclusive, evidence‑based exoskeleton guidelines
- Safer overhead work practices
- Worker‑centred implementation strategies
- Informed decision‑making by employers, safety professionals, and equipment designers
By integrating psychophysical and biomechanical perspectives, the study contributes critical insight into how exoskeletons can be used to support, rather than inadvertently disadvantage, a diverse construction workforce.
Key Applications
The research highlights that sex and body morphology influence both perceived and physiological responses to exoskeleton assistance. Although exoskeletons increased acceptable load capacity for all participants, they did not eliminate baseline differences between males and females or between body archetypes.
This underscores the importance of:
- Avoiding one‑size‑fits‑all assumptions
- Evaluating both perceived risk tolerance and objective muscle loading
- Considering whether increased confidence in load handling aligns with actual reductions in physiological risk
