Background: The sit‐to‐stand (STS) test is a crucial tool for sarcopenia assessment. However, the two most widely used diagnostic frameworks differ in their conceptualization of the test. The European Working Group on Sarcopenia in Older People 2 views the STS test primarily as a proxy for muscle strength, while the Asian Working Group for Sarcopenia 2019 (AWGS 2019) classifies it as a measure of physical performance. This discrepancy poses challenges to conceptual clarity in both research and practice. Recent advancements in pose‐estimation algorithms allow for kinematic assessment using a standard handheld devices, providing a simple and cost‐effective alternative to conventional motion‐analysis. Methods: A total of 129 community‐dwelling older adults (mean age 71.8 years) who could ambulate independently underwent assessments of muscle strength (knee extensor and handgrip strength), physical performance (usual walking speed, Timed Up and Go [TUG] velocity and Short Physical Performance Battery [SPPB]) and muscle mass (appendicular skeletal muscle index by bioelectrical impedance analysis). Kinematic analysis of the 30‐s sit‐to‐stand (30‐s STS) was conducted using 2D pose estimation to derive peak STS power and joint angles. For validation, a subset of 20 participants completed 30‐s STS trials that were recorded concurrently using 2D pose estimation, optical motion capture and force‐plate recordings. The correlation between peak STS power, five times sit‐to‐stand (5x‐STS) time, and 30‐s STS repetitions with clinical indicators was examined. Results: Peak STS power correlated strongly with muscle strength and mass (knee extensor strength r = 0.64; handgrip r = 0.64; ASMI r = 0.70; all p < 0.001) but only weakly with physical performance (usual walking speed: r = 0.19, p = 0.030; TUG velocity and SPPB: p > 0.05). In contrast, the 5x‐STS time and 30‐s STS repetitions showed moderate to strong associations with physical performance (e.g., SPPB r = −0.79 and 0.52, respectively; both p < 0.001) but did not correlate with strength or muscle mass. Despite systematic biases between pose estimation and the reference, the agreement was high (intraclass correlation coefficient for peak STS power = 0.94; joint‐angles = 0.83–0.89). In sex‐stratified, within‐subject mixed‐effects models, changes in posture and timing explained modest variance in ΔPeak STS power (marginal R ² = 0.024 in men; 0.138 in women). Conclusions: Peak STS power correlated more strongly with muscular strength, while 5x‐STS and 30‐s STS tests were more closely related to physical performance. These findings align better with and provide stronger support for the AWGS 2019 framework.

Background : The lumbar stabilization exercise is one of the most recommended treatments in medical professionals for patients suffering from low back pain. However, because lumbar stabilization exercise is calisthenics, it is challenging to perform because of the body load of the elderly, disabled, and patients that lack muscle strength. Additionally, it interferes with the effect of exercise because it can strain parts of the body. Methods : To overcome them, a compliant anti-gravity rehabilitation proto-type device using the Series Elastic Actuator (SEA) was developed previously to provide quantitative assist force to the person, producing similar exercise effects with calisthenics. From an exercise experiment with 20 participants, it caused discomfort to participants during exercise owing to the non-ergonomic design of the previous device. Different muscle activation tendencies were observed between calisthenics and exercise using the device. For advanced technical solutions to clinical needs, which is exercise using the rehabilitation robot to produce a similar effect to calisthenics, the mechanical design of the rehabilitation robot was improved based on the previous device after receiving feedback from clinical trials and static analysis. For the safety of exercise using the robot, a cascade PID-PI controller was used to reduce the influence of friction and disturbance due to the external movement. Results : Surface electromyography(sEMG) signal from lumbar muscles showed desired monotonic reduction ratio and higher similarity results compared to the previous device, which proved the exercise effectiveness using the robot. Conclusion : The proposed robot is considered as a solution to a clinical need of lumbar rehabilitation for the elderly, disabled, and patients.

Lumbar stabilization exercises are commonly employed in the rehabilitation of patients with low back pain. However, many patients discontinue these exercises, generally calisthenics using various postures or tools, due to the difficulty of providing an appropriate exercise load intensity. This challenge results in an inability to apply the desired strength to the target lumbar muscles and sometimes leads to an excessive load on unintended areas during calisthenics. Consequently, a method that enables patients to exercise continuously and progressively recover is required, specifically one that can target the lumbar muscles with a desired load. To address this issue, we propose a rehabilitation assistive device that quantitatively controls the lumbar spine load. In isometric lumbar stabilization exercises, our method involves precise compensation for gravity. The device, equipped with a series elastic actuator, is positioned beneath the patient in a lying posture. It applies an assistive force in the direction opposite to gravity, enabling precise control of the load on the lumbar region and reducing the vertical load on the spine. To validate the effectiveness of our proposed method, we conducted experiments with 20 healthy subjects across three exercises and analyzed the electromyography signal using nonparametric statistical methods. Our objective was to determine whether the load on the target lumbar muscles could be precisely and gradually controlled. The statistical results indicate that exercises performed using the proposed device produce statistically significant load changes in the target lumbar muscles.

This paper presents a novel rehabilitation robot designed to address the challenges of Passive Range of Motion (PROM) exercises for frozen shoulder patients by integrating advanced scapulohumeral rhythm stabilization. Frozen shoulder is characterized by limited glenohumeral motion and disrupted scapulohumeral rhythm, with therapist-assisted interventions being highly effective for restoring normal shoulder function. While existing robotic solutions replicate natural shoulder biomechanics, they lack the ability to stabilize compensatory movements, such as shoulder shrugging, which are critical for effective rehabilitation. Our proposed device features a 6 Degrees of Freedom (DoF) mechanism, including 5 DoF for shoulder motion and an innovative 1 DoF Joint press for scapular stabilization. The robot employs a personalized two-phase operation: recording normal shoulder movement patterns from the unaffected side and applying them to guide the affected side. Experimental results demonstrated the robot’s ability to replicate recorded motion patterns with high precision, with Root Mean Square Error (RMSE) values consistently below 1 degree. In simulated frozen shoulder conditions, the robot effectively suppressed scapular elevation, delaying the onset of compensatory movements and guiding the affected shoulder to move more closely in alignment with normal shoulder motion, particularly during arm elevation movements such as abduction and flexion. These findings confirm the robot’s potential as a rehabilitation tool capable of automating PROM exercises while correcting compensatory movements. The system provides a foundation for advanced, personalized rehabilitation for patients with frozen shoulders.

Lumbar braces are recommended for lumbar diseases or low back pain, particularly for use in activities of daily living. However, prolonged use of lumbar braces can lead to functional limitations and side effects such as muscle atrophy and psychological dependence due to their static nature. To address these limitations, this study proposes a wearable robot in the form of a lumbar brace to provide adaptive lumbar stabilization. The proposed robot uses an actuator to drive a tension wire, which applies force to the pulley mechanism located on both sides of the brace. This mechanism provides dynamic abdominal pressure to the torso. The assisting force is determined based on the lumbar motion, which is measured using inertial sensors. By providing abdominal pressure and dynamic support, the proposed robot is able to compensate for the shortcomings of current braces and increase lumbar stability. To assess the effectiveness, a pilot experiment was conducted with five healthy subjects. The subjects performed lumbar-specific exercises, Electromyography and linear acceleration were taken to evaluate the impact on muscle activity and lumbar stability. The results indicated that proposed device is possible to reduce the burden on the muscles and increase the spine stability by dynamically providing abdominal pressure.

Cardiopulmonary Resuscitation (CPR) is crucial in emergency cardiac arrest situations. To reduce paramedic fatigue and ensure steady CPR performance, automated chest compression devices have been developed. However, current devices do not consider the patient’s chest condition, potentially causing internal injuries and reducing cardiac output. This paper proposes a chest compression device using a linear series elastic actuator (SEA) for CPR. The SEA can compress and measure force simultaneously, adjusting compliance based on the spring’s stiffness. Unlike other SEAs that use compression springs, this design employs a torsion spring. The mechanism and the working principle of the linear SEA are presented, along with an analysis of the custom torsion spring. Experiments on a test bench validate the spring’s stiffness and assess the device’s performance. Additional experiments with a CPR training manikin demonstrate the device’s suitability for compression depth tracking and force control. The proposed design is space-efficient and offers accurate compression force sensing, providing a promising solution for effective CPR in emergencies.