Search Results (149)

Accurate estimation of upper-limb joint angles is essential in biomechanics, rehabilitation, and wearable robotics. While inertial measurement units (IMUs) offer portability and flexibility, systems requiring multiple inertial sensors can be intrusive and complex to deploy. In contrast, optical motion capture (MoCap) systems provide precise tracking but are constrained to controlled laboratory environments. This study presents a deep learning-based approach for estimating shoulder and elbow joint angles using only three IMU sensors positioned on the chest and both wrists, validated against reference angles obtained from a MoCap system. The input data includes Euler angles, accelerometer, and gyroscope data, synchronized and segmented into sliding windows. Two recurrent neural network architectures, Convolutional Neural Network with Long-short Term Memory (CNN-LSTM) and Bidirectional LSTM (BLSTM), were trained and evaluated using identical conditions. The CNN component enabled the LSTM to extract spatial features that enhance sequential pattern learning, improving angle reconstruction. Both models achieved accurate estimation performance: CNN-LSTM yielded lower Mean Absolute Error (MAE) in smooth trajectories, while BLSTM provided smoother predictions but underestimated some peak movements, especially in the primary axes of rotation. These findings support the development of scalable, deep learning-based wearable systems and contribute to future applications in clinical assessment, sports performance analysis, and human motion research. Full article

Background and Objectives: Lymphedema is one of the most important morbid complications of modified radical mastectomy (MRM) surgery. It can cause limb movement restriction and psychosocial deformities in some patients. This study aimed to determine and compare the physiological and pathological changes that develop in the axillary venous structures in patients who underwent axillary lymph node dissection (ALND) and sentinel lymph node biopsy (SLNB). Materials and Methods: Patients diagnosed with breast cancer who underwent MRM and breast-conserving surgery (BCS) plus SLNB between 2017 and 2022 were retrospectively examined. The patients’ operation side and contralateral axillary vein diameter and the difference between them, axillary vein flow rate and the difference between them, axillary vein wall thickness and the difference between them, severity of lymphedema, extremity joint restriction examination, and the Nottingham Health Profile (NHP) data were recorded. The relationship of these parameters with the lymph node dissection width and radiotherapy was analyzed. Results: Fifty-eight patients in total were included in the study. In the distribution of lymphedema and lymphedema severity according to ALND groups, there is a statistically significant difference (p < 0.001). A statistically significant difference was determined in the distribution of the difference in the axillary vein blood flow rate and axillary vein diameter difference between the two arms according to the lymph node dissection groups. In the distribution of physical therapy and rehabilitation scales according to the lymph node dissection groups, a significant difference was found in the disabilities of the arm, shoulder, and hand (DASH), shoulder flexion restriction variables, and NHP sleep variables (all p < 0.001). Conclusions: This study demonstrated that ALND leads to more pronounced physiological and pathological changes in axillary venous structures—including increased vein wall thickness, altered flow rates, and diameter differences—compared to SLNB combined with breast-conserving surgery. These changes may be attributed to lymphovenous disruption and postoperative edema. Furthermore, radiotherapy appears to contribute to these changes, though to a lesser extent than ALND. Therefore, SLNB followed by radiotherapy may be preferable in eligible patients to reduce postoperative complications such as lymphedema, joint restriction, and sleep disturbances. Full article

Snowboard Big Air (SBA), recognized as an Olympic discipline since 2018, emphasizes maneuver difficulty as a key scoring criterion, requiring athletes to integrate technical skill with adaptive responses to dynamic environments in order to perform complex aerial rotations. The takeoff phase is critical, determining both flight trajectory and rotational performance through coordinated lower limb extension and upper body movements. Despite advances in motion analysis technology, quantitative assessment of key takeoff parameters remains limited. This study investigates parameters related to performance, joint kinematics, and rotational kinetics during the SBA takeoff phase to identify key factors for success and provide practical guidance to athletes and coaches. Eleven athletes from the Chinese national snowboard team performed multiple backside tricks (720°, 1080°, 1440°, and 1800°) at an outdoor dry slope with airbag landings. Three-dimensional motion capture with synchronized cameras was used to collect data on performance, joint motion, and rotational kinetics during takeoff. The results showed significant increases in most measured metrics with rising trick difficulty from 720° to 1800°. The findings reveal that elite SBA athletes optimize performance in high-difficulty maneuvers by increasing the moment of inertia, maximizing propulsion, and refining joint kinematics to enhance rotational energy and speed. These results suggest that training should emphasize lower limb power, core and shoulder strength, flexibility, and coordination to maximize performance in advanced maneuvers. Full article

This study aimed to investigate the influence of different walking speeds on shoulder and elbow joint kinematics, specifically focusing on range of motion, angular velocity, and angular acceleration during arm swing. The natural rhythm of human gait was studied to develop an effective mechanical interface, particularly with respect to joint impedance and force controllability. The independent variable in this study was walking speed, operationalized at four levels—3.6 km/h (slow), 4.2 km/h (preferred walking speed, PWS), 5.4 km/h (normal), and 7.2 km/h (fast)—and defined as a within-subject factor. The dependent variables consisted of quantitative kinematic parameters, including joint range of motion (ROM, in degrees), peak and minimum joint angular velocity (deg/s), and peak and minimum joint angular acceleration (deg/s²). For each subject, data from twenty gait cycles were extracted for analysis. The kinematic variables of the shoulder and elbow were analyzed, showing increasing trends as the walking speed increased. As walking speed increases, adequate arm swing contributes to gait stability and energy efficiency. Notably, the ROM of shoulder was slightly reduced at the PWS compared to the slowest speed (3.6 km/h), which may reflect more natural and coordinated limb movements at the PWS. Dynamic covariation of torque patterns in the shoulder and elbow joints was observed, reflecting a synergistic coordination between these joints in response to human body movement. Full article

This paper describes ongoing work surrounding the creation of a recognition system for Mexican Sign Language (LSM). We propose a general sign decomposition that is divided into three parts, i.e., hand configuration (HC), arm movement (AM), and non-hand gestures (NHGs). This paper focuses on the AM features and reports the approach created to analyze visual patterns in arm joint movements (wrists, shoulders, and elbows). For this research, a proprietary dataset—one that does not limit the recognition of arm movements—was developed, with active participation from the deaf community and LSM experts. We analyzed two case studies involving three sign subsets. For each sign, the pose was extracted to generate shapes of the joint paths during the arm movements and fed to a CNN classifier. YOLOv8 was used for pose estimation and visual pattern classification purposes. The proposed approach, based on pose estimation, shows promising results for constructing CNN models to classify a wide range of signs. Full article

Given the cervical spinal cord’s role in locomotor and rhythmic upper limb tasks, its neuromodulation has emerged as an important area of study for understanding human spinal rhythmogenesis. We previously demonstrated that, under unloading conditions, arm muscle vibrostimulation can elicit non-voluntary upper limb oscillations. In this study, we investigated the effects of transcranial magnetic stimulation (TMS) of the motor cortex during both voluntary and non-voluntary (vibration-induced) rhythmic arm movements. We analyzed motor-evoked potentials, mean arm muscle activity, and kinematic parameters of arm movements, including cycle duration and shoulder and elbow joint angular oscillations. Motor-evoked potentials in proximal arm muscles were significantly modulated during both movement types. Notably, low-frequency TMS markedly enhanced non-voluntary arm oscillations, whereas its effect on voluntary movements was statistically non-significant. This differential response is likely due to the absence of characteristic supraspinal influences in sensory-induced spinal activation during non-voluntary movements. These findings align with previous evidence showing that supraspinal pathways facilitate rhythmogenesis in the lower limbs, and they now extend this concept to the upper limbs. Overall, our results suggest that therapies aimed at modulating cervical central pattern generators may benefit from the active engagement of supraspinal motor circuits. Full article

Shoulder girdle plays a dominant role in coordinating the natural movements of the upper arm. Inverse kinematics, optimization, and data-driven approaches are usually used to conduct motion retargeting. However, these methods do not consider shoulder girdle movement. When the kinematic structure of human and that of exoskeletons share a similar joint configuration, analytical motion retargeting methods can be used for exoskeletons with shoulder girdle mechanism. This paper proposes a vector-based analytical motion retargeting approach for exoskeletons with shoulder girdle mechanism. The approach maps the vectors of the upper limb segments to the joint space using vector-based methods. Simulation results using four different motion descriptions confirm the method’s accuracy and efficiency. Full article

The aim of this pilot study was to investigate the feasibility of markerless tracking to assess upper body movements of children with and without human immunodeficiency virus encephalopathy (HIV-E). Sagittal and frontal video recordings were used to track anatomical landmarks with the DeepLabCut pre-trained human model in five children with HIV-E and five typically developing (TD) children to calculate shoulder flexion/extension, shoulder abduction/adduction, elbow flexion/extension and trunk lateral sway. Differences in joint angle trajectories of the two cohorts were investigated using a one-dimensional statistical parametric mapping method. Children with HIV-E showed a larger range of motion in shoulder abduction and trunk sway than TD children. In addition, they showed more shoulder extension and more lateral trunk sway compared to TD children. Markerless tracking was feasible for 2D movement analysis and sensitive to observe expected differences in upper limb and trunk sway movements between children with and without HIVE. Therefore, it could serve as a useful alternative in settings where expensive gait laboratory instruments are unavailable, for example, in clinical centers in low- to middle-income countries. Future research is needed to explore 3D markerless movement analysis systems and investigate the reliability and validity of these systems against the gold standard 3D marker-based systems that are currently used in clinical practice. Full article

Background and Objectives: Although virtual reality (VR) has been shown to be effective in rehabilitation through motor learning principles, its impact on upper extremity function, particularly in the context of console use, remains unclear. Materials and Methods: This study aimed to investigate the effects of VR-based task-oriented movement on the upper extremity of healthy individuals. A total of 26 healthy individuals performed task-oriented movements in both real and virtual environments in a randomized order. All participants completed a single session of task-oriented movements using a VR Goggle system in a virtual setting. Physiotherapists designed immersive VR-based experiences and 3D screen-based exergames for this study. Upper extremity function was assessed using several measures: joint position sense (JPS) of the wrist and shoulder was evaluated using a universal goniometer, reaction time was measured via a mobile application, and gross manual dexterity was assessed using the box-and-block test (BBT). Evaluations were conducted before and after the interventions. Results: The results showed that JPS remained similar between conditions, while BBT performance improved in both groups. However, the reaction time increased significantly only after VR intervention (p < 0.05). No significant period or carryover effects were observed across the parameters. These findings suggest that VR-based task-oriented training positively influences reaction time and supports hand function. Moreover, VR systems that simulate joint position sense similar to real-world conditions may be beneficial for individuals with musculoskeletal motor deficits. Conclusions: These results highlight the potential for integrating VR technology into rehabilitation programs for patients with neurological or orthopedic impairments, providing a novel tool for enhancing upper extremity function and injury prevention strategies. Full article

Reaching is a fundamental motor skill essential for daily living, with over 50% of daily activities involving reaching movements. Understanding the development of postural adjustments made during reaching in early childhood is crucial for motor development. This study investigated the developmental characteristics of postural adjustments made by children aged 3–6 years during reaching tasks. A total of 135 typically developing children from Chinese kindergartens participated in this study. Kinematic and electromyographic (EMG) data were collected using an infrared motion capture system and surface electromyography, respectively. A two-way ANCOVA was performed to examine the effects of age and gender on kinematic and electromyographic parameters. Post hoc analyses revealed that completion time and shoulder angle showed a linear decreasing trend (p < 0.05). The variable wrist joint had an increasing trend in the high-touch task, while the elbow joint showed a nonlinear decreasing trend (p < 0.05). EMG results regarding Extensor Carpi Ulnaris (ECU) showed a decreasing trend at all phases (p < 0.05). The developmental patterns observed suggest that children progressively utilize more distal (wrist) and fewer proximal (elbow and shoulder) joints during reaching, indicating the maturation of motor patterns. However, the mechanisms of anticipation and compensation for children aged 3–6 are not yet fully understood. Full article

Background and Objectives: Scapular muscles are crucial in controlling scapular movement, ensuring proper alignment, and preventing injuries during shoulder joint motion. The shoulder abduction angle is one of the most important factors when performing exercises to improve scapular movement control. The Pilates reformer arm work (AW) movement can be performed with different shoulder abduction angles. Therefore, this study analyzed the differences in scapular muscle activation depending on the shoulder abduction angle during the AW movement. Materials and Methods: Twenty-six healthy adult males performed the AW movement under four shoulder abduction angle conditions (0°, 90°, 135°, 160°). When performing the AW in the four conditions, surface electromyography analyzed the muscle activation of the upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), serratus anterior (SA), posterior deltoid (PD), and levator scapulae (LS), and the muscle activation ratios of the UT/LT, LS/LT, UT/SA, and LS/SA. Results: The UT, LT, and SA muscle activation increased proportionally with the increasing shoulder abduction angle (p < 0.001). The LT showed the highest muscle activity at the shoulder abduction angle of 135° (p < 0.001). The MT and PD showed the highest muscle activities at the shoulder abduction angle of 90° (p < 0.001). The muscle activity ratios of the UT/LT and LS/LT were the lowest at the shoulder abduction angles of 90° and 135° (p < 0.001). The muscle activity ratio between the UT/SA and LS/SA was the lowest at the 135° and 160° shoulder abduction angles (p < 0.001). Conclusions: Our findings highlight the impact of the shoulder abduction angle on scapular muscle activation, suggesting that different angles may be used to engage specific muscles during Pilates reformer arm work exercises selectively. This insight can guide exercise interventions for individuals aiming to improve their scapular control and stability. Full article

Assessing shoulder joint range of motion (ROM) is essential for diagnosing musculoskeletal disorders and optimizing treatments. This single-center pilot study evaluated the reliability and validity of iBalance, a single-camera markerless motion capture system, for measuring shoulder ROM. Forty participants (30 healthy individuals and 10 patients with adhesive capsulitis) underwent measurements of seven shoulder joint movements. Each movement was assessed three times by two raters using both iBalance and a goniometer, with measurements repeated after 1 week. The iBalance demonstrated excellent inter- and intra-rater reliability for flexion (ICC = 0.93 [0.91–0.95], 0.91 [0.88–0.94]), abduction (ICC = 0.97 [0.95–0.98], 0.93 [0.91–0.95]), and passive abduction (ICC = 0.97 [0.96–0.98], 0.98 [0.97–0.98]). The system also showed strong validity compared to the goniometer for flexion (ICC = 0.85 [0.68–0.92]), abduction (ICC = 0.95 [0.94–0.96]), and passive abduction (ICC = 0.97 [0.96–0.98]). Bland–Altman plots showed high consistency between the two devices for flexion, abduction, and passive abduction, with most data points falling within the limits of agreement. Patients with adhesive capsulitis exhibited greater variability than healthy individuals. No adverse events were reported, supporting the safety of the system. This study highlights the potential of a single-camera markerless motion capture system for diagnosing and treating shoulder joint disorders. The iBalance showed clinical applicability for measuring flexion, abduction, and passive abduction. Future enhancements to the algorithm and the incorporation of advanced metrics could improve its performance, facilitating broader clinical applications for diagnosing complex shoulder conditions. Full article

Background: Kinematics experts and physical therapists have implemented the use of sensors for 3D motion analysis, both for static and dynamic movements. XClinic movement sensors are advanced devices designed to analyze movement patterns with high precision. The aim of this study was to validate wearable XClinic sensors for range of motion (ROM) in healthy subjects and obtain normative data. Participants were enrolled at the Sapienza University of Rome in 2024. All participants had to be healthy subjects aged between 18 and 65 years. Data on their demographics, employment and physical activity were collected. All the subjects were tested to assess the active ROM of their shoulder, hip, knee and ankle bilaterally. The same movements were tested using a goniometer to investigate validity, and SF-36 was administered. Fifty subjects were enrolled. The mean age was 28.2 (SD 10.8) years. For the left shoulder, construct validity showed statistically significant values for flexion, extension and extra-rotation, while for the right shoulder, construct validity showed statistically significant values for all movements except intra-rotation. The results concerning the right hip showed statistically significant values for flexion, extra-rotation, intra-rotation and adduction. The left hip showed statistically significant values for all movements except extension. Both the right and left knees showed statistically significant values for flexion. Both the right and left ankles showed statistically significant values for all movements. XClinic sensors offer a reliable and valid solution for the precise monitoring of the ROM of the shoulder and lower limb joints, making them an invaluable asset for clinicians and researchers. Full article

Background/Objectives: Repeated spiking and serving movements in volleyball can lead to alterations in shoulder range of motion among athletes, potentially increasing the risk of shoulder instability and injury. Hence, assessing and understanding the shoulder range of motion of volleyball players is a critical concern. Therefore, this study aimed to understand and evaluate the bilateral shoulder joint range of motion (ROM) in high-school male volleyball athletes and to discover the adaptation characteristics. Methods: Forty high-school male volleyball athletes participated in this study. Shoulder ROM measurements were taken via video with an iPhone 12 Pro Max, and we analyzed the ROM data using Kinovea software (Version 0.9.5) for both the dominant and non-dominant side. The shoulder ROM measurements included shoulder hyper-extension (SE), flexion (SF), internal rotation (IR), external rotation (ER), horizontal adduction (Sadd), and horizontal abduction (Sabd). After taking shoulder ROM measurements, the total rotational range of motion (TROM) was calculated based on the participants’ shoulder internal rotation and external rotation data, and we calculated the incidence of glenohumeral internal rotation deficiency (GIRD) among participants. Paired samples t-tests were used to analyze shoulder ROM differences between the dominant and non-dominant side. Results: The dominant side of the shoulder showed significantly lower internal rotation (dominant side: 42.17 ± 11.23°; non-dominant side: 52.14 ± 10.46°; p = 0.000) and total rotational ROM (dominant side: 137.11 ± 13.09°; non-dominant side: 141.96 ± 13.22°; p = 0.021) compared to the non-dominant side. Conversely, the dominant side of the shoulder exhibited significantly greater external rotation (dominant side: 94.96 ± 10.02°; non-dominant side: 89.83 ± 7.84°; p = 0.001) and shoulder horizontal adduction (dominant side: 44.87 ± 8.10°; non-dominant side: 39.60 ± 7.24°; p = 0.000) than the non-dominant side. No significant differences were found in other measured parameters. The incidence of glenohumeral internal rotation deficiency (GIRD) among all subjects was 37.5%. Conclusions: High-school male volleyball athletes in this study exhibited tightness in the posterior shoulder of their dominant side, indicating specific adaptations in shoulder ROM and a considerable prevalence of GIRD, observed in approximately one-quarter of the athletes. In conclusion, these data suggest that stretching and eccentric muscle training focusing on the posterior shoulder have potential value in mitigating these adaptations and reducing the risk of shoulder injuries. Full article

Objective: Upper crossed syndrome (UCS) is an abnormal upper extremity movement pattern characterized by muscle tightness in the neck, shoulders, and upper back, coupled with weakness in opposing muscle groups. This study aimed to investigate the effectiveness of Pilates training combined with fascial massage as an intervention in office workers with UCS. Methods: 34 subjects were recruited and randomly divided into an experimental group (n = 17) and a control group (n = 17). The control group underwent 12 weeks of Pilates training, and the experimental group received 12 weeks of Pilates training combined with fascial massage. Body posture was assessed using the forward head angle (FHA) and forward shoulder angle (FSA), joint mobility was evaluated using cervical spine range of motion (ROM), muscle activity was assessed using surface electromyography (sEMG), and quality of life was evaluated using pain level (VAS) and cervical spine dysfunction index (NDI). Results: After 12 weeks of intervention, the FHA, FSA, VAS, and NDI of the experimental group were significantly lower than those of the pre-intervention group (p < 0.05) and significantly lower than those of the control group (p < 0.05); the extension and left–right rotation cervical spine ROM of the experimental group were significantly higher than those of the pre-intervention group (p < 0.05) and significantly higher than those of the control group (p < 0.05); and sEMG indexes (mean power frequency and median frequency) of the upper trapezius and the pectoralis major in the experimental group were significantly higher than those of the pre-intervention group (p < 0.05) and significantly higher than the control group (p < 0.05). Conclusion: Compared with Pilates training alone, Pilates training combined with fascial massage demonstrated a more significant effect in improving muscle activation, body posture, and pain and enhancing the quality of life for patients with UCS. Full article