Science on Your Shoulders: Proven Reductions in Strain and Fatigue Across Multiple Tasks
Hundreds of studies have examined how exoskeletons can reduce strain and fatigue, but the sheer volume of research can make it difficult for non-experts to see what matters most. This post brings key evidence together in a clear, practical format—focusing on common tasks such as welding, sealing, overhead assembly, lifting, plastering, and ceiling construction, and highlighting critical indicators like fatigue and precision.
Across these use cases, the findings point to Skelex 360 as a trusted solution—validated in both laboratory studies and real working environments.
Key benefits reported in research
By supporting the shoulders and arms, Skelex 360 makes overhead work more sustainable. Research has shown that it:
- Reduces shoulder muscle activity by 30% to 50%
- Lowers the feeling of heaviness and fatigue
- Does not interfere with accuracy or fine motor skills
- Keeps heart strain lower during repetitive tasks
Cardiac costs: lower fatigue during repetitive and precise tasks [1]
A study from École Centrale de Nantes (France) examined the influence of Skelex 360 on cardiac cost—an indicator related to physical demand and fatigue—during both repetitive (R) and precise (P) tasks.
- Participants: 36 healthy individuals (18 male, 18 female)
- Task R: Using a 6 kg power tool for fastening nuts with arms elevated near eye height
- Task P: Drawing projected lines on a wall using an interactive pen
Findings:
For both tasks, a significant reduction in cardiac cost was observed while wearing the exoskeleton—despite added weight and physical constraints. This was supported by subjective questionnaires evaluating global and local perceived effort, showing statistically significant reductions overall and locally, especially for the shoulders, arms, and neck.
The reduction in cardiac cost indicates lower fatigue experienced during task performance, and when combined with earlier EMG studies, supports the conclusion that Skelex 360 can help users feel less tired during certain tasks.
Fig 1a. A participant performing the precision task P without exoskeleton (a) and with the exoskeleton (b).
Fig 1b. Global and local perceived effort for specific parts of the body without (NoExo) and with Exoskeleton (Exo) for all tasks; dotted lines indicate global strain means.
Fig 1c. Evaluation of ACC*d (h) for Task R and task P with (Exo) and without (NoExo) exoskeleton.
Precision: maintaining fine motor control—even under fatigue [2]
Research involving the University of Hamburg and Institut Universitaire de France studied how Skelex 360 affects fine motor control during precision tasks, with and without muscular fatigue.
- Participants: N = 10 (5 male, 5 female)
- Tasks: Single-task (ST) and dual-task (DT) industrial exercises involving speed and accuracy
- Precision task: Overhead targeting using a nail gun across three target sizes (based on Fitts’ law speed–accuracy trade-off), with and without Skelex 360
Findings:
Substantial reductions in M. deltoideus muscle activity were observed:
- ST: 26% reduction before fatigue; 32% after fatigue
- DT: 53% reduction before fatigue; 40% after fatigue
Most importantly, the study concluded that:
1. Healthy young participants can adapt easily to Skelex 360 for fast, accurate tasks, and
2. Wearing Skelex 360 does not alter the ability to manage the speed–accuracy trade-off.
Fig 2a. (from left to right) Utilization of the nail gun without the exoskeleton. Utilization of the nail gun with the exoskeleton, Fatigue protocol
Figure 2b. Fitts’ Law was preserved across all conditions (exo/no exo, fatigue/no fatigue, ST/DT). The slope remained unchanged, suggesting that participants adapted motor strategies to maintain control. While wearing an exoskeleton, users could still perform accurate, timed movements reliably
Sealing: aerospace task support with comfort and precision gains [3]
Aerospace manufacturing often requires arm elevation from below elbow height to overhead. Research from Wichita State University (USA) evaluated passive upper-arm exoskeletons during aircraft sealing tasks.
- Task context: Sealing fuselage joints using sealant and smoothing tools
- Participants: 16 experienced aircraft manufacturing employees (8 male, 8 female)
Findings:
The study demonstrated a 30–40% reduction in trapezius muscle activation. It also highlighted Skelex 360 as the most comfortable device among those tested, with improvements in both worker comfort and precision during overhead sealing operations.
Fig 3a. Horizontal sealing tasks and starting postures (from left to right) a) standing sealing along upper stringer b) standing sealing along lower stringer c) seated sealing along upper stringer d) seating sealing along lower stringer
Fig 3b. Mean percent MVC for preferred side muscles significantly affected by exoskeletons during standing horizontal sealing.
Fig 3c. Mean exoskeleton preference ranking for use during sealing tasks (1=most preferred to 3=least preferred).
Welding: measurable improvements in welding performance [4]
A study conducted by Fraunhofer IPA (Germany) investigated welding and grinding workflows using a welding simulator.
- Participants: 15 subjects with welding experience
- Workflow: 1-hour sequence abstracting welding and grinding tasks
- Positions tested:
PF: Vertical welding in front of the body
PE: Overhead welding
- Key performance metric: “Travel speed” (rated 0–100), a factor tied to weld quality
Findings:
- PF position: +5.8% improvement using Skelex 360
- PE position: +28.8% improvement using Skelex 360
The “travel speed” score showed a statistically significant increase when Skelex 360 was used.
Fig 4a. (Left) First-person view of the subject for position PF during the welding sequence; (right) exemplary illustration of position PE during the grinding sequence.
Fig 4b. Results of the statistical analysis of the parameter travel speed for the entire population
Plastering: reduced shoulder muscle activity in a real-life scenario [5]
Plastering ceilings involves long sequences of complex overhead movements and heavy tools, often leading to fatigue in the shoulders, arms, and upper back. An application study by TNO (Netherlands) assessed Skelex 360 during plastering tasks.
- Participants: 11 experienced plasterers
- Tasks: Applying plaster on walls/ceilings and finishing surfaces in a special setup
- Measurement: EMG sensors, with and without Skelex 360
Findings:
Significant reductions in muscle activity were found for some shoulder muscles when using the exoskeleton. Importantly, none of the muscles studied showed a significant increase in activity across the tasks.
This study supports Skelex 360’s efficacy for demanding overhead tasks using objective measurements in a real-life scenario.
Fig 5a. Overview of the set-up and activities on the ceiling. screeding (left) and finishing with a plastering spatula (right).
Fig 5b. Muscle activation in Exo and NoExo conditions for different plastering tasks. Each panel represents one plastering task; the upper row shows working on the wall, and the lower row shows working on the ceiling.
Overhead assembly: reduced muscle activity in both arms, especially non-dominant [6]
Overhead assembly often requires one arm to stabilize while the other performs the main action—creating rapid fatigue in both arms, and often higher strain in the supporting (non-dominant) arm. A study from Aalborg University (Denmark) investigated Skelex 360 during an overhead assembly task.
- Participants: 18 healthy males
- Task: Pick up a screw with the non-dominant hand and screw it with the dominant hand (10 screws per subject)
Findings:
Muscle activation was reduced across all muscles measured. A notable observation was that the reduction was substantially higher in the non-dominant arm, which may contribute to improved perceived fatigue for common two-handed tasks across many industries.
Fig 6a. Overhead Assembly Task setup
Fig 6b. Comparison of the mean muscle activation between participants in the two conditions, Free (gray) and Exo (orange), during the overhead assembly task.
Lifting: reduced deltoid activity, with considerations for dynamic tasks [6]
Aalborg University also assessed Skelex 360 during repeated lifting, a common task associated with musculoskeletal disorders (MSDs).
- Participants: 18 healthy males
- Task: Lift a 10 kg box from the floor to the top of a table while rotating the body 90 degrees
- Pace: 15 reps/min (metronome), six consecutive lifts, repeated three times per condition
Findings:
Activation of Anterior Deltoid (AD) and Medial Deltoid (MD) was significantly reduced on both sides when using Skelex 360. However, some muscle groups showed increased activation, possibly due to the back being constrained by the structure.
This suggests that for highly dynamic tasks like lifting, even with a flexible and comfortable device, some users may experience a feeling of constraint.
Fig 7a. Overhead Assembly Task setup
Fig 7b. Comparison of the mean muscle activation between participants in the two conditions, Free (gray) and Exo (orange), during the lifting task.
Ceiling construction: lower muscle activity and perceived exertion, strong user preference [7]
Ceiling construction involves continuous arm elevation and is a risk factor for MSDs. A study by TNO (Netherlands) evaluated Skelex 360 in a simulated, realistic construction environment.
- Participants: 11 experienced ceiling constructors
- Tasks: 9 different ceiling construction tasks, each lasting 3–4 minutes
- Evaluation: Objective EMG + subjective Rate of Perceived Exertion (RPE)
Findings:
EMG results showed substantial reductions in muscle activity, consistent with earlier research. RPE was lower across tasks, with a clear preference for using Skelex 360 during heavier jobs such as machine sanding, manual sanding, and filling joints.
Preference: 10 out of 11 participants preferred using the exoskeleton for the tasks.
Fig 8a. Boxplots of Rate of Perceived Exertion (RPE) in the dominant arm
Fig 8b. Participant’s intention to wear the Skelex 360 when weighing benefits and drawbacks. The higher the values, the higher the intention; the lower the values, the lower the intention. Each horizontal line represents the answer of a single participant.
Summary
This document presents results from independent research carried out in collaboration with universities and institutes. Findings are based on EMG measurements, RPE data, and performance tests in real industrial tasks.
Across the studies and task types, the evidence consistently points to Skelex 360 helping to reduce muscle activity, lower fatigue-related strain, and maintain precision—particularly for overhead and sustained arm-elevation work.
