This quasi-experimental study evaluates the effectiveness of a passive lower-limb exoskeleton (Chairless Chair® 2.0) in redistributing plantar pressure and reducing injuries caused by prolonged standing in workplace settings. Conducted on 25 participants, the research measured plantar pressure, body sway, and postural stability with and without the exoskeleton using a pressure platform. Additionally, user fatigue and satisfaction were assessed through validated questionnaires (Borg CR10, QUEST 2.0). The results aim to determine the device's preventive potential regarding musculoskeletal and circulatory issues, contributing to improved ergonomic health and work performance.
Prolonged standing is a common requirement in various professional sectors (e.g., healthcare, industry), and is associated with increased risks of musculoskeletal and circulatory disorders, especially in the lower limbs. Conditions such as plantar fasciitis, chronic venous insufficiency, and pressure ulcers are prevalent. These affect worker health, comfort, and productivity, and impose economic burdens on employers and healthcare systems. Objective To evaluate the effectiveness of a passive exoskeleton for the lower limbs (Chairless Chair® 2.0) in redistributing plantar pressure and reducing musculoskeletal injuries associated with prolonged standing. The study also investigates the device's influence on postural stability, perceived fatigue, and user comfort. Methodology Study design: Quasi-experimental with repeated measures (participants act as their own control). Participants: 25 adult workers (aged 18-60), with ≥6 months of exposure to prolonged standing at work. Exclusion criteria included pre-existing musculoskeletal or circulatory disorders and use of orthopedic devices. Device: Chairless Chair® 2.0 by Noonee Germany GmbH-a passive, non-powered exoskeleton enabling users to alternate between standing and semi-sitting positions. Tools and Measurements: Podoprint S4 pressure platform to measure: Plantar pressure distribution (forefoot, midfoot, heel) Body sway and stability (center of pressure displacement) CR10 Borg scale for fatigue QUEST 2.0 for usability and satisfaction Data Analysis: Quantitative analysis using SPSS and JASP Paired t-tests or Wilcoxon tests for comparisons Spearman correlations and Chi-square tests for categorical relationships Statistical significance set at p \< 0.05 Key Variables Dependent: Plantar pressure (kPa), body sway (cm²), postural stability (mm/s), fatigue perception, comfort. Independent: Use of exoskeleton, age, gender, BMI, type of footwear, reported discomfort. Ethical and Legal Framework Ethical approval granted by the Comité de Ética de la Universidad Católica de Valencia (CEI). Compliance with LOPDGDD, GDPR, and Declaration of Helsinki. Informed consent obtained; anonymity and data protection were strictly maintained. Expected Outcomes Reduction in peak plantar pressure and postural sway when using the exoskeleton. Improvement in stability and fatigue levels. Enhanced user comfort and satisfaction, making the device a feasible ergonomic intervention. Significance This study seeks to fill a gap in scientific literature regarding the biomechanical benefits of passive lower-limb exoskeletons in real work environments, providing evidence for their role in injury prevention, ergonomic improvement, and worker well-being.
Study Type
OBSERVATIONAL
Enrollment
25
Participants used a passive lower-limb exoskeleton (Chairless Chair® 2.0) during their regular work tasks involving prolonged standing. The device enables a semi-seated posture without the need for external power, aiming to reduce lower limb strain. The intervention involved each participant performing their typical standing tasks once with the exoskeleton and once without it, in a within-subject repeated-measures design. Each participant served as their own control. Objective data were collected using a plantar pressure platform (Podoprint S4, Namrol) to measure: Plantar pressure distribution Postural stability Body sway
Clinicas UCV
Valencia, València, Spain
Change in Plantar Pressure Distribution With vs. Without Passive Exoskeleton Use Change in Plantar Pressure Distribution With vs. Without Passive Exoskeleton Use Change in Plantar Pressure Distribution With vs. Without Passive Exoskeleton Use
Mean plantar pressure values (in kilopascals, kPa) will be measured in key foot regions (heel, midfoot, forefoot) using the Podoprint S4 platform. Data will be collected under two conditions: while performing tasks with the Chairless Chair® 2.0 and without it. The comparison will assess the exoskeleton's effectiveness in redistributing plantar loads during prolonged standing.
Time frame: Immediately after task performance in each condition (with and without exoskeleton) - approximately same workday or within 1-2 days
Change in Postural Stability With vs. Without Passive Exoskeleton
Postural stability and center of pressure (COP) displacement (in cm² and mm/s) will be measured during static standing using the Podoprint S4 pressure platform. The goal is to evaluate whether the exoskeleton improves balance and reduces body sway during prolonged standing tasks.
Time frame: Immediately after task performance in each condition (with and without exoskeleton)
Perceived Fatigue After Work Tasks With vs. Without Exoskeleton
Fatigue in the lower extremities will be assessed using the Borg Scale CR10, a validated ordinal questionnaire ranging from 0 (no exertion) to 10 (maximum exertion). A higher score indicates greater perceived fatigue. Participants will report their perception of exertion immediately after completing the tasks, both with and without the exoskeleton.
Time frame: Immediately after task completion in each condition - within same workday
User Comfort and Usability of the Passive Exoskeleton
Participants will complete the QUEST 2.0 (Quebec User Satisfaction Evaluation of Assistive Technology) questionnaire, which includes scores on a scale from 1 (very dissatisfied) to 5 (very satisfied). Higher scores reflect greater satisfaction and positive perception of the comfort, usability and acceptability of the device. The results will allow assessment of the practical acceptability of the exoskeleton in real work environments.
Time frame: After using the exoskeleton during a full work session - within 1 day
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