Background: Shoulder muscle weakness (e.g. in Erb’s palsy) limits the ability to lift the arm and requires high muscular activation to perform and sustain elevation leading to rapid fatigue. This leads to a restricted reachable workspace resulting in impairments in daily activities . Although passive shoulder exoskeletons based on gravity compensation reduce muscle activity in healthy individuals, the effects on muscle activation, shoulder kinematics and activities of daily life under reduced shoulder strength conditions remains unclear. To our knowledge, no orthosis/exoskeleton is currently available for supporting arm elevation through gravity compensation principles during activities of daily life. Methods: This mixed-methods feasibility study evaluated whether passive gravity-compensating shoulder assistance can restore muscle-driven elevation capacity and reduce muscular activation under graded weakness. Additionally, user-informed design requirements were identified using semi-structured interviews exploring daily limitations and needs for support in adults with Erb’s palsy. In parallel, musculoskeletal simulations in OpenSim modelled abduction and forward flexion under strength reductions corresponding to MRC levels 2-4. Outcomes included peak and cumulative muscle activation and the resulting maximal muscle-driven active humerothoracic elevation range of motion. Assistance was implemented using gravity scaling and a physically modelled cam-cable actuator. Results: Interview findings highlighted rapid fatigue, restricted elevation, and reliance on compensatory movement strategies, alongside strong requirements regarding comfort, adjustability and selective use. Simulations showed that weakness reduced maximal muscledriven range of motion. Passive assistance restored full elevation with 15-45% gravitational compensation, depending on severity of weakness, while reducing peak and cumulative activation without disproportionate compensatory activation. Conclusion: Passive shoulder elevation support, implemented through both gravity scaling and a modelled cam-cable actuator, under simulated weakness and aligns with user-identified needs, supporting further orthosis development.

Preventive, personalized treatment of biopsychosocial (BPS) functional decline or stagnation in the rehabilitation process requires early prediction of those at risk. Ambulant monitoring of objective physical activity using wearable accelerometers could be a quantitative, noninvasive, and affordable method to gain insight into current and future biopsychosocial functioning.

In this retrospective study, Random Forest Regression was used to predict cross-sectional and longitudinal Functional Ambulation Category (FAC) and Six-item Cognitive Impairment Test (6CIT) after hip fracture using ambulatory accelerometry data. Accelerometry data and BPS functional assessments were available of 49 participants of the HIPCARE study, assessing prognostic determinants of outcome after hip fracture in the elderly.

Overall, cross-sectional FAC scores three months after hip fracture could be predicted with moderately low error, and categorized regression predictions showed high precision and recall. Cross-sectional 6CIT and both longitudinal regression models underperformed, but categorized regression predictions revealed mixed but more promising precision and recall.

It is expected that the predictive performance of models can be improved by increasing participant sample size with balanced samples over population-specific, prevalent ranges of BPS outcome scales and exploring additional machine learning models. In the future, accurate accelerometry-based predictions for individual patients needing rehabilitation could support personalized treatment and improve long-term biopsychosocial functioning.

Introduction:Timely personalized treatment of functional decline depends on early ambulant identification of persons at risk. Regularity of daily body acceleration, quantified by sample entropy (SampEn), is associated with fall risk and is a potential proxy for functional (biopsychosocial) resilience.
Objective: This cross-sectional study associates SampEn of daily life accelerometry with physical (short physical performance battery, SPPB [0 12]) and cognitive functioning (cognitive impairment test, 6 CIT [0-28]).Method: Data was provided from the HIPCARE cohort of 51 community-dwelling adults [81 (75 – 89)] after femur fracture. The SPPB, CIT, and 7 days accelerometry were recorded at three months follow-up after hip surgery. The mean SampEn for different activities was compared between patients with low (<4), moderate (4-9), and high (>9) SPPB and between low (<8) and high (>7) CIT with a significance of p≤0.05Results: Moderate SPPB scores had more regularity (lower SampEn) in complete daily life acceleration signals and during stair-walking than the high SPPB group. In addition, the cognitive impaired group (i.e., high CIT) had more regularity (lower SampEn) than the healthy group during cycling and sitting activities.Discussion and conclusions: More regular accelerations indicate the development of limited physical performance and deterioration of cognitive functions. The findings advocate that acceleration entropy in daily life activities is a promising proxy for physical and mental (biopsychological) functions. A large-scale longitudinal study is needed to examine the potential added value of daily acceleration for the early detection of biopsychosocial functioning.