Trial Outcomes & Findings for Chairless Chair Exoskeleton. Work-physiological-biomechanical Analysis of the Lower Extremities (NCT NCT03134144)
NCT ID: NCT03134144
Last Updated: 2020-06-16
Results Overview
Indicator for the balance of the study participants. This outcome was measured using a force plate, in which the anteroposterior and mediolateral directions of the center of pressure are recorded. The center of pressure is a visual projection of the center of mass of the participant. For the anteroposterior direction of the center of pressure, a positive value \[mm\] represents the anterior direction and a negative value \[mm\] represents the posterior direction. For the mediolateral direction of the center of pressure, a positive value \[mm\] represents the right-lateral direction and a negative value \[mm\] represents the left-lateral direction. For this outcome, we recorded the anteroposterior direction of the center of pressure. The outcome is in mm, where neg. reflects the posterior direction and pos. the anterior direction.
COMPLETED
NA
46 participants
10 minutes of 2 hours
2020-06-16
Participant Flow
Volunteering participants were recruited via the investigators that collaborated in this study.
None of the recruited volunteering participants was excluded based on the exclusion criteria. One subject dropped out prior to the measurement due to time constraints.
Participant milestones
| Measure |
First Without Exoskeleton Then With Exoskeleton
Subject will perform the conditions as described under "model description" first with and then without the exoskeleton.
|
First With Exoskeleton and Then Without Exoskeleton
Subject will perform the conditions as described under "model description" first with and then without the exoskeleton.
Exoskeleton "Chairless Chair": One solution to reduce the exposure of employees to associated risks for developing work-related musculoskeletal disorders is to use exoskeletons. Using such a device in dynamic environments has the advantage over, e.g., robotics because it does not need any programming or teaching of robots. Moreover, exoskeletons are worn at the body and do not have to overcome spatial issues. In a recent review, 26 different exoskeletons have been described of which only two were designed to support the lower body during heavy work (de Looze et al. 2015). For lower intensive work tasks, like assembly tasks in the automobile industry, no study has focused on using exoskeletons to relieve employees while performing the work standing.
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|---|---|---|
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Overall Study
STARTED
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15
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30
|
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Overall Study
COMPLETED
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15
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30
|
|
Overall Study
NOT COMPLETED
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0
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0
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Reasons for withdrawal
Withdrawal data not reported
Baseline Characteristics
Race and Ethnicity were not collected from any participant.
Baseline characteristics by cohort
| Measure |
First Without Exoskeleton Then With Exoskeleton
n=15 Participants
Subject will perform the conditions as described under "model description" first without and then with the exoskeleton.
|
First With Exoskeleton Then Without
n=30 Participants
Subject will perform the conditions as described under "model description" first with and then without the exoskeleton.
|
Total
n=45 Participants
Total of all reporting groups
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|---|---|---|---|
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Age, Continuous
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23.9 years
STANDARD_DEVIATION 2.7 • n=15 Participants
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25.2 years
STANDARD_DEVIATION 3.0 • n=30 Participants
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24.8 years
STANDARD_DEVIATION 2.9 • n=45 Participants
|
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Sex: Female, Male
Female
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0 Participants
n=15 Participants
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0 Participants
n=30 Participants
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0 Participants
n=45 Participants
|
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Sex: Female, Male
Male
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15 Participants
n=15 Participants
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30 Participants
n=30 Participants
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45 Participants
n=45 Participants
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Race and Ethnicity Not Collected
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—
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—
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0 Participants
Race and Ethnicity were not collected from any participant.
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PRIMARY outcome
Timeframe: 10 minutes of 2 hoursPopulation: In total, two participants dropped out due to missing information with regard to the base of support, which is necessary to calculate the centre of pressure.
Indicator for the balance of the study participants. This outcome was measured using a force plate, in which the anteroposterior and mediolateral directions of the center of pressure are recorded. The center of pressure is a visual projection of the center of mass of the participant. For the anteroposterior direction of the center of pressure, a positive value \[mm\] represents the anterior direction and a negative value \[mm\] represents the posterior direction. For the mediolateral direction of the center of pressure, a positive value \[mm\] represents the right-lateral direction and a negative value \[mm\] represents the left-lateral direction. For this outcome, we recorded the anteroposterior direction of the center of pressure. The outcome is in mm, where neg. reflects the posterior direction and pos. the anterior direction.
Outcome measures
| Measure |
First Without Exoskeleton Then With Exoskeleton
n=14 Participants
Subject will perform the conditions as described under "model description" first without the exoskeleton and then with the exoskeleton.
|
First With Exoskeleton and Then Without Exoskeleton
n=29 Participants
Subject will perform the conditions as described under "model description" first with the exoskeleton and then without the exoskeleton.
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|---|---|---|
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Center of Pressure
Experimental conditions without exoskeleton
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-42.76 mm
Interval -48.19 to -25.55
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-34.98 mm
Interval -49.16 to -22.18
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Center of Pressure
Experimental conditions with exoskeleton
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-118.34 mm
Interval -128.42 to -107.43
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-122.16 mm
Interval -130.8 to -111.58
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PRIMARY outcome
Timeframe: 10 minutes of 2 hoursPopulation: Data of 7 participants are missing due to failed data recordings.
Indicator for the muscular load in the lower back (M. erector spinae lumbalis) that may change when wearing the passive exoskeleton. The muscle activity was recorded using bipolar surface electromyography, during which two electrodes are placed on the muscle belly. The absolute value of muscle activity recordings is in microvolt, but since this is difficult to interpret, we have normalized this to a reference voluntary contraction that was executed by each participant prior to the experiment. The unit of measure for normalized muscle activity therefore is a percentage, i.e. a percentage of the electrical activity during the reference voluntary contraction \[%RVE\].
Outcome measures
| Measure |
First Without Exoskeleton Then With Exoskeleton
n=13 Participants
Subject will perform the conditions as described under "model description" first without the exoskeleton and then with the exoskeleton.
|
First With Exoskeleton and Then Without Exoskeleton
n=26 Participants
Subject will perform the conditions as described under "model description" first with the exoskeleton and then without the exoskeleton.
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|---|---|---|
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Muscle Activity of the Lower Back (M. Erector Spinae Lumbalis)
Experimental conditions without the exoskeleton
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11.02 %RVE
Interval 7.06 to 13.89
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7.78 %RVE
Interval 6.62 to 11.7
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Muscle Activity of the Lower Back (M. Erector Spinae Lumbalis)
Experimental conditions with the exoskeleton
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6.80 %RVE
Interval 5.39 to 11.11
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8.29 %RVE
Interval 4.58 to 11.44
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SECONDARY outcome
Timeframe: 10 minutes of 2 hoursPopulation: Data of 8 subjects is missing due to failed recordings.
The posture of the back may indicate whether the relative body posture changed when wearing the passive exoskeleton compared to not wearing the passive exoskeleton. In the current study, back posture was recorded using two gravimetric position sensors placed on the thoracic vertebrae T3 and lumbal vertebrae L3. The difference between both position sensors represented the trunk forward flexion angle \[°\].
Outcome measures
| Measure |
First Without Exoskeleton Then With Exoskeleton
n=13 Participants
Subject will perform the conditions as described under "model description" first without the exoskeleton and then with the exoskeleton.
|
First With Exoskeleton and Then Without Exoskeleton
n=24 Participants
Subject will perform the conditions as described under "model description" first with the exoskeleton and then without the exoskeleton.
|
|---|---|---|
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Back Posture: Upper Back Forward Flexion Angle With Respect to the Perpendicular (Earth)
Experimental conditions without the exoskeleton
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11.55 °
Interval 4.83 to 17.1
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5.10 °
Interval -3.31 to 10.83
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Back Posture: Upper Back Forward Flexion Angle With Respect to the Perpendicular (Earth)
Experimental conditions with the exoskeleton
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25.00 °
Interval 14.89 to 36.85
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20.95 °
Interval 12.3 to 31.08
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SECONDARY outcome
Timeframe: 10 minutes of 2 hoursPopulation: All participants were included in this analysis.
Indicate whether participants develop feelings of discomfort in different experimental conditions when wearing or not wearing the passive exoskeleton. Discomfort was recorded using an 11-point numeric rating scale, running from 0 (no discomfort at all) to 10 (maximally imaginable discomfort). So, the outocme is in \[units on a scale from 0 to 10\].
Outcome measures
| Measure |
First Without Exoskeleton Then With Exoskeleton
n=15 Participants
Subject will perform the conditions as described under "model description" first without the exoskeleton and then with the exoskeleton.
|
First With Exoskeleton and Then Without Exoskeleton
n=30 Participants
Subject will perform the conditions as described under "model description" first with the exoskeleton and then without the exoskeleton.
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|---|---|---|
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Subjective Feeling of Overall Discomfort
Experimental conditions with the exoskeleton
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2 units on a scale
Interval 0.0 to 2.0
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0 units on a scale
Interval 0.0 to 2.0
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Subjective Feeling of Overall Discomfort
Experimental conditions without the exoskeleton
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0 units on a scale
Interval 0.0 to 0.0
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0 units on a scale
Interval 0.0 to 1.25
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SECONDARY outcome
Timeframe: 2 hoursPopulation: All participants could be included in the analysis.
A questionnaire indicating whether wearing the passive exoskeleton during simluated assembly tasks is evaluated as comfortable, feasible, and usable. Below, the 10 statements questions as part of the participant evaluation questionnaire are shown with an interpretation of the score. 1 generally reflects "I do not agree at all" whereas 10 generally reflects "I fully agree". Depending on the question, a score closer or equal to 1 is better and 10 worse, or vice versa. Statements 1-8: a higher score (i.e., close to 10) is considered better Statements 9-10: a lower score (i.e., close to 1) is considered better
Outcome measures
| Measure |
First Without Exoskeleton Then With Exoskeleton
n=15 Participants
Subject will perform the conditions as described under "model description" first without the exoskeleton and then with the exoskeleton.
|
First With Exoskeleton and Then Without Exoskeleton
n=30 Participants
Subject will perform the conditions as described under "model description" first with the exoskeleton and then without the exoskeleton.
|
|---|---|---|
|
Participant Evaluation
The exoskeleton was comfortable
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6.4 units on a scale
Standard Deviation 2.1
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6.9 units on a scale
Standard Deviation 1.9
|
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Participant Evaluation
The exoskeleton was easy to operate / handle
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8.4 units on a scale
Standard Deviation 1.4
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8.7 units on a scale
Standard Deviation 1.3
|
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Participant Evaluation
I was able to work precisely with the exoskeleton
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9.1 units on a scale
Standard Deviation 1.1
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8.7 units on a scale
Standard Deviation 1.3
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Participant Evaluation
The exoskeleton is suitable for the simulated task
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8.3 units on a scale
Standard Deviation 1.8
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8.1 units on a scale
Standard Deviation 1.6
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Participant Evaluation
I can imagine working with the exoskeleton longer
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7.4 units on a scale
Standard Deviation 2.2
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6.9 units on a scale
Standard Deviation 2.1
|
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Participant Evaluation
The working posture was comfortable in high sit
|
5.9 units on a scale
Standard Deviation 2.0
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5.1 units on a scale
Standard Deviation 2.0
|
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Participant Evaluation
The working posture was comfortable in low sit
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6.9 units on a scale
Standard Deviation 2.2
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7.2 units on a scale
Standard Deviation 1.7
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Participant Evaluation
I felt safe to use the exoskeleton in high sit
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7.5 units on a scale
Standard Deviation 2.1
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6.6 units on a scale
Standard Deviation 2.1
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Participant Evaluation
I felt safe to use the exoskeleton in low sit
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8.1 units on a scale
Standard Deviation 1.9
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7.8 units on a scale
Standard Deviation 1.4
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Participant Evaluation
I wanted to change position in high sit
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6.3 units on a scale
Standard Deviation 2.5
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5.6 units on a scale
Standard Deviation 2.9
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Participant Evaluation
I wanted to change position in low sit
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4.9 units on a scale
Standard Deviation 2.6
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5.0 units on a scale
Standard Deviation 2.8
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Adverse Events
Without Exoskeleton
With Exoskeleton
Serious adverse events
Adverse event data not reported
Other adverse events
Adverse event data not reported
Additional Information
Tessy Luger
Institute of Occupational and Social Medicine and Health Services Research, University of Tübingen
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place