Goal: To develop bending angle sensors based on double-layer capacitance for monitoring joint angles during cycling exercises. Methods: We develop a bending angle sensor based on double-layer capacitive and conducted three stretching, bending, and cycling tests to evaluate its validity. Results: We demonstrate that the bending angle sensor based on double-layer capacitance minimizes the change in the capacitance difference in the stretching test. The hysteresis and root mean square error (RMSE) compared with the optical motion capture show hysteresis: 8.0% RMSE and 3.1° in the bending test. Moreover, a cycling experiment for human joint angle measurements confirm the changes in accuracy. The RMSEs ranged from 4.7° to 7.0°, even when a human wears leggings fixed with the developed bending-angle sensor in the cycling test. Conclusion: The developed bending angle sensor provides a practical application of the quantitative and observational evaluation tool for knee joint angles.

Improvement of physical and cognitive capabilities through physical activity (PA) contributes to well-being in older age. Unfortunately, many older adults lack sufficient PA, due to reasons such as PA not being enjoyable for them. As a result, older adults are unable to maintain their motivation for the initiation and continuation of PA. In our previous works, a boxing glove-type sensory augmentation system was developed to solve this problem by inducing enjoyment during PA. However, the effect of our device on physical and cognitive capabilities, which are crucial for well-being, and motivation for initiation and continuation of PA remains unclarified. In this study, we aimed to evaluate these effects. We hypothesized that our device may help improve capabilities, and that the enjoyment it provides may potentially contribute to increased motivation for initiation and continuation of PA. Fourteen healthy older adults participated in the study. Kickboxing lessons for the older adults using our device were conducted a total of five times over a six-week period, and the participants were free to attend the sessions as many times as they wished. They participated in three measurement sessions: pre-measurement before the lesson period, post-lesson measurement after each lesson, and post-measurement at the end of the lesson period to evaluate the effects of our device. Physical capabilities were assessed through two-step, stand-up, and center-of-pressure tests. Cognitive capabilities were assessed using illustration memory and computation tests. Mental state was assessed using a positive and negative affect schedule (PANAS). Subjective evaluations of enjoyment and motivation for the initiation and continuation of PA through the use of our device were also conducted. In the results, physical and cognitive capabilities and mental states tended to improve. Subjective evaluations indicated increased enjoyment from using our device and greater perceived effectiveness in motivating PA initiation and continuation. These evaluations improved over time. While the pre-post design without a control group limits causal interpretation, improvements in physical, cognitive, and mental states may have contributed to enhanced enjoyment. As a result, the device may have the potential to enhance motivation for initiation and continuation PA in older adults.

BackgroundHip osteoarthritis (HOA) often leads to compensatory movements such as trunk lateral bending during gait due to pain and restricted range of motion. Because multiple joints coordinate to control the center of mass (CoM) during walking, quantitatively assessing compensatory strategies is essential to understand HOA pathology and to develop rehabilitation programs. Traditional indices do not adequately evaluate multi-joint coordination; however, Uncontrolled Manifold (UCM) analysis enables assessment of multiple-joint utilization to control CoM in HOA. This study aimed to investigate differences in inter-joint coordination between patients with HOA and controls by focusing on frontal-plane CoM control during gait using UCM analysis.MethodsWe extracted data from a public gait dataset for 80 asymptomatic individuals and 106 patients with HOA. Segment angles were treated as elemental variables and frontal-plane CoM as the performance variable in UCM analysis. The variance of elemental variables that did not affect the performance variable was defined as VUCM; the variance of those that did was defined as VORT. Synergy index (ΔV) was calculated and compared between groups.ResultsCompared with asymptomatic individuals, patients with HO showed significantly higher VUCM and VORT (p < 0.05). However, ΔVZ did not differ significantly (p > 0.05).ConclusionDespite the increases in VUCM and VORT, ΔVZ remained at a consistent level. These findings suggest that patients with HOA control CoM by utilizing multiple joints to compensate for pain and restricted range of motion. These results may inform rehabilitation planning and outcome evaluation that consider motor-control characteristics in HOA.

We proposed a new method to measure swallowing in this study. A flexible polymer sensor was used to measure human swallowing. Electromyogram (EMG) of suprahyoid muscles were measured as a reference of swallowing. We also developed a measurement system for the flexible polymer sensor, which consists of two measurement circuits; the 1^st one measures the voltage of flexible polymer sensor, and the 2^nd one EMG of suprahyoid muscles. We conducted measurement experiments focused on human swallowing to confirm the ability of this sensor. At the experiment one subject was asked to sit in three different postures and to drink a cup of water. Results show that human swallowing can be detected by this flexible polymer sensor.