Exploring the Effect of the Hypershell Hip Exoskeleton on Fatiguing, Everyday Activities in Older Adults

• Performance test (Other), also known as FATIG'AGE protocol: Participants will perform the FATIG'AGE multi-task functional mobility protocol. The protocol includes a fixed sequence of daily activities such as walking, sit-to-stand transitions, stair ascent and descent, slope walking, walking on uneven surfaces, carrying an object, and dual-task walking.
• Hypershell assistance (EXO-ON Actuation) (Device): Participants wear the Hypershell hip exoskeleton with active assistance. In the active-assistance condition, the device uses motion sensors to detect the user's movements and provides powered assistance to support hip movement during functional mobility tasks

Primary outcomes

• Rate of Perceived Fatigue Progression [During each experimental session, up to 60 minutes]: Rating of Perceived Fatigue (RPF) will be assessed verbally using the Borg Category-Ratio 10 (CR10) scale after each task of the FATIG'AGE protocol. The Borg CR10 ranges from 0 (no exertion) to 10 (maximal exertion). The rate of increase in RPE across consecutive task executions will be determined for each experimental condition, with a lower rate indicating a slower development of perceived exertion.
• Protocol Duration Until Termination [During each experimental session, up to 60 minutes]: Total time, in minutes, that the participant performs the FATIG'AGE protocol before reaching a predefined termination criterion: Borg CR10 greater or equal to two consecutive score of 8, or the maximum protocol duration of 60 minutes. Longer duration indicates that the participant was able to perform the protocol for longer before termination.
• Number of Executed Tasks Until Protocol Termination [During each experimental session, up to 60 minutes]: Total number of individual FATIG'AGE task executions completed before reaching a predefined termination criterion: Borg CR10 equal or greater to two consecutive scores of 8, or the maximum protocol duration of 60 minutes. A higher number indicates that more functional mobility tasks were completed before protocol termination.

Secondary outcomes

• Global Perceived Effect of the Hypershell [Immediately after each applicable experimental session]: Participants will rate the perceived effect of wearing the HyperShell on their physical performance using the Global Perceived Effect (GPE) scale. The GPE is a 7-point Likert scale ranging from perceived deterioration to perceived improvement. The questionnaire will be administered following the HyperShell transparent and active-assistance conditions.
• Usability of the HyperShell Assessed With the System Usability Scale [Immediately after the Hypershell active-assistance experimental session]: Usability of the Hypershell will be assessed using the 10-item System Usability Scale (SUS). Items are rated on a 5-point Likert scale and transformed into a total score ranging from 0 to 100, with higher scores indicating greater perceived usability.
• User Experience With the Hypershell Assessed With the User Experience Questionnaire [Immediately after the Hypershell active-assistance experimental session]: User experience with the Hypershell will be assessed using the 26-item User Experience Questionnaire (UEQ). The questionnaire assesses six dimensions: attractiveness, perspicuity, efficiency, dependability, stimulation, and novelty. Items are scored on a semantic differential scale ranging from -3 to +3, with higher scores indicating a more positive user experience.
• Lower-Limb Muscle Activity [Continuously during each experimental session, up to 60 minutes]: Surface electromyography will be continuously recorded from selected lower-limb muscles (knee extensor, foot dorsi- and plantar flexor) during the FATIG'AGE protocol. Muscle activation amplitude and frequency will be derived from the EMG signal and compared between experimental conditions. Unit of Measure: percent of reference contraction (%)
• Heart Rate [Continuously during each experimental session, up to 60 minutes.]: Heart rate will be continuously recorded during the FATIG'AGE protocol using electrocardiography. Heart rate will be examined across the protocol and between experimental conditions. Unit of Measure: beats per minute (bpm)
• Respiratory Rate [Continuously during each experimental session, up to 60 minutes.]: Respiratory rate will be continuously recorded using an inductive plethysmography band during the FATIG'AGE protocol and examined across the protocol and between experimental conditions. Unit of Measure: breaths per minute
• Galvanic Skin Response [Continuously during each experimental session, up to 60 minutes.]: Galvanic skin response will be continuously recorded using finger electrodes during the FATIG'AGE protocol and examined across the protocol and between experimental conditions. Unit of Measure: microsiemens (µS).
• Lower-Limb Muscle Oxygen Saturation [Continuously during each experimental session, up to 60 minutes.]: Muscle oxygen saturation will be continuously recorded from selected lower-limb muscles (knee extensor, foot dorsi- and plantar flexor) using near-infrared spectroscopy sensors during the FATIG'AGE protocol and examined across the protocol and between experimental conditions. Unit of Measure: percent (%)
• Changes in Motion Data [Continuously during each experimental session, up to 60 minutes.]: Inertial Measurement Unit (IMU) data will be collected continuously throughout the FATIG'AGE protocol. The IMUs will record motion-related signals, including segment orientation, linear acceleration, and angular velocity. Data acquisition will explore changes in kinematics and gait parameters.

Sex: All, ages: 65 Years to any, accepts healthy volunteers

Inclusion Criteria:

* Aged 65 years or older
* Good mobility according to the International Classification of Functioning, Disability and Health (ICF) mobility classification

Exclusion Criteria:

* Physical injury or disorder that does not allow good physical performance

• Eva Swinnen, Prof, Principal investigator, Vrije Universiteit Brussel