NCT03134144

Chairless Chair Exoskeleton. Work-physiological-biomechanical Analysis of the Lower Extremities

Completed NA Results posted Last updated 16 June 2020

What this trial tests

NA trial testing Exoskeleton "Chairless Chair" in Healthy in 46 participants. Completed in 15 October 2017.

Timeline

1 May 2017

Primary endpoint
15 October 2017

15 October 2017

Quick facts

Lead sponsor	University Hospital Tuebingen
Phase	NA
Status	Completed
Study type	INTERVENTIONAL
Allocation	randomized
Design	crossover
Masking	none
Primary purpose	basic science
Enrollment	46
Start date	1 May 2017
Primary completion	15 October 2017
Estimated completion	15 October 2017
Sites	1 location across Germany

Drugs / interventions tested

• Exoskeleton "Chairless Chair"

Conditions studied

• Healthy — all drugs for Healthy →

Sponsor

University Hospital Tuebingen

Who can join

Adults 18 to 40, male only, with Healthy. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

Center of Pressure Primary · 10 minutes of 2 hours

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 negat

Experimental conditions without exoskeleton

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	-42.76	-48.19 – -25.55
First With Exoskeleton and Then Without Exoskeleton	-34.98	-49.16 – -22.18

Experimental conditions with exoskeleton

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	-118.34	-128.42 – -107.43
First With Exoskeleton and Then Without Exoskeleton	-122.16	-130.80 – -111.58

Muscle Activity of the Lower Back (M. Erector Spinae Lumbalis) Primary · 10 minutes of 2 hours

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 th

Experimental conditions without the exoskeleton

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	11.02	7.06 – 13.89
First With Exoskeleton and Then Without the Exoskeleton	7.78	6.62 – 11.70

Experimental conditions with the exoskeleton

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	6.80	5.39 – 11.11
First With Exoskeleton and Then Without the Exoskeleton	8.29	4.58 – 11.44

Back Posture: Upper Back Forward Flexion Angle With Respect to the Perpendicular (Earth) Secondary · 10 minutes of 2 hours

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 \[°\].

Experimental conditions without the exoskeleton

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	11.55	4.83 – 17.10
First With Exoskeleton Then Without Exoskeleton	5.10	-3.31 – 10.83

Experimental conditions with the exoskeleton

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	25.00	14.89 – 36.85
First With Exoskeleton Then Without Exoskeleton	20.95	12.30 – 31.08

Subjective Feeling of Overall Discomfort Secondary · 10 minutes of 2 hours

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 \[units on a scale from 0 to 10\].

Experimental conditions without the exoskeleton

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	0	0 – 0
First With Exoskeleton Then Without Exoskeleton	0	0 – 1.25

Experimental conditions with the exoskeleton

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	2	0 – 2
First With Exoskeleton Then Without Exoskeleton	0	0 – 2

Participant Evaluation Secondary · 2 hours

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

The exoskeleton was comfortable

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	6.4	± 2.1
First With Exoskeleton Then Without	6.9	± 1.9

The exoskeleton was easy to operate / handle

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	8.4	± 1.4
First With Exoskeleton Then Without	8.7	± 1.3

I was able to work precisely with the exoskeleton

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	9.1	± 1.1
First With Exoskeleton Then Without	8.7	± 1.3

The exoskeleton is suitable for the simulated task

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	8.3	± 1.8
First With Exoskeleton Then Without	8.1	± 1.6

I can imagine working with the exoskeleton longer

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	7.4	± 2.2
First With Exoskeleton Then Without	6.9	± 2.1

The working posture was comfortable in high sit

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	5.9	± 2.0
First With Exoskeleton Then Without	5.1	± 2.0

The working posture was comfortable in low sit

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	6.9	± 2.2
First With Exoskeleton Then Without	7.2	± 1.7

I felt safe to use the exoskeleton in high sit

Group	Value	95% CI
First Without Exoskeleton Then With Exoskeleton	7.5	± 2.1
First With Exoskeleton Then Without	6.6	± 2.1

Sponsor's own description

Standing work is associated with increased risks of venous and musculoskeletal disorders; particularly low back pain is commonly reported in prolonged standing work. In manufacturing work, workstations often do not allow standing aids due to insufficient functional and spatial conditions. In 2014, the car manufacturer Audi introduced the lower leg exoskeleton developed by Noonee to their employees working in the factories. This exoskeleton, the 'Chairless Chair' has the advantage that standing work can be performed while technically sitting on this device. The exoskeleton offers the potential for reduced awkward body postures, but it is unclear which physiological and biomechanical loads are influenced and how. This proposal provides a study design evaluating the 'Chairless Chair' in a laboratory setting, by testing its effectiveness in terms of physiological and biomechanical parameters. It is suggested to compare different assembly tasks while wearing the exoskeleton, compared with not wearing the exoskeleton. The 'Chairless Chair' is developed in one size only, which is why we propose to include participants of different body height, which will enable us to investigate whether body height influences the effectiveness of wearing the device.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

1. Postural Control When Using an Industrial Lower Limb Exoskeleton: Impact of Reaching for a Working Tool and External Perturbation.
   Steinhilber B, Seibt R, Rieger MA, Luger T. · · 2022 · cited 16× · PMID 32988243 · DOI 10.1177/0018720820957466