Upper Body Posture Recognition Using Inertial Sensors and Recurrent Neural Networks

Inadequate sitting posture can cause imbalanced loading on the spine and result in abnormal spinal pressure, which serves as the main risk factor contributing to irreversible and chronic spinal deformity. Therefore, sitting posture recognition is important for understanding people’s sitting behaviors and for correcting inadequate postures. Recently, wearable devices embedded with microelectromechanical systems (MEMs) sensors, such as inertial measurement units (IMUs), have received increased attention in human activity recognition. In this study, a wearable device embedded with IMUs and a machine learning algorithm were developed to classify seven static sitting postures: upright, slump, lean, right and left bending, and right and left twisting. Four 9-axis IMUs were uniformly distributed between thoracic and lumbar regions (T1-L5) and aligned on a sagittal plane to acquire kinematic information about subjects’ backs during static-dynamic alternating motions. Time-domain features served as inputs to a signal-based classification model that was developed using long short-term memory-based recurrent neural network (LSTM-RNN) architecture, and the model’s classification performance was used to evaluate the relevance between sensor signals and sitting postures. Overall results from performance evaluation tests indicate that this IMU-based measurement and LSTM-RNN structural scheme was appropriate for sitting posture recognition.

Postural Variabilities Associated with the Most Comfortable Sitting Postures: A Preliminary Study

This study examined postural variabilities based on the self-perceived most comfortable postures of 12 participants (six men and six women) when sitting on three commonly used types of chairs (a stool, computer chair, and gaming chair). Participants’ global joint angles were recorded and analyzed. Of the chairs studied, the stool was not adjustable, but the computer and gaming chairs were moderately and highly adjustable, respectively. During the test, participants were encouraged to adjust the chairs until they perceived that the most comfortable posture had been reached. The results demonstrated that in a sitting position perceived to be comfortable, the participants’ postural variabilities with respect to global joint angle, calculated from five repetitions, were unexpectedly high for all three chair types, at approximately 9.4, 10.2, and 11.1° for head inclination, trunk angle, and knee angle, respectively. The average differences in range for each joint angle among the three chair types were relatively low, with all values within 3°. The result also showed that gender (p < 0.01) and chair type (p < 0.001) significantly affected trunk angle, whereas these variables did not affect head inclination or knee angle (p > 0.05). The preliminary results observed unexpectedly high variabilities in sitting posture when the participants sat at a posture that they perceived to be the most comfortable. The findings also indicated an inherent difference in comfortable sitting posture between genders; women tend to extend their trunk backward more than men. For permanent use with only an initial adjustment and memory-aided seat design, designers should minimize the loads that are borne by body parts over a prolonged period due to an unchanging sitting posture.

Esophageal Motility Disorders: Are We Missing in Our Busy Endoscopy Practice?

Esophageal motility disorders (EMDs) form a significant part of a busy endoscopist's practice. Endoscopy plays an all-encompassing role in the diagnosis and management of EMDs including achalasia cardia. The focus on in-vogue third-space endoscopic procedures such as per-oral endoscopic myotomy often digresses the important role of endoscopy. Endoscopic evaluation forms the part of standard first-line evaluation of any dysphagia and serves to rule out a secondary cause such as an esophagogastric junction malignancy and eosinophilic esophagitis. Moreover, endoscopic evaluation may itself provide corroborative evidence that may contribute to the diagnosis of the motility disorder. Achalasia cardia may present with a wide spectrum of endoscopic findings from being entirely normal and the well-known and pathognomonic dilated sigmoid-shaped esophagus with food residue, to lesser-known ornate signs. The evidence on the role of endosonography in EMDs is conflicting and largely restricted to evaluation of pseudoachalasia. High-resolution manometry (HRM) remains the gold standard in the diagnosis of EMDs. Endoscopists must also keep abreast of the latest iteration of the Chicago classification version 4.0, which differs significantly from its predecessor in being more stringent in making diagnosis of esophagogastric junction outflow obstruction and disorders of peristalsis since these manometric findings may be seen in normal individuals and may be mimicked by opioid use and gastroesophageal reflux. The latest rendition also includes the use of provocative maneuvers and testing in both supine and sitting posture. Despite being the gold standard, there are certain lacunae in the use and interpretation of the Chicago classification of which the users should be well aware. Emerging technologies such as functional lumen imaging probe and planimetry, and timed barium esophagogram fill the lacuna in diagnosis of these motility disorders, which at times is beyond the resolution of HRM.

Inter-group Transfer of Anti-alcoholic Effect of Nux vomica 200 CH through the Body of a Live Toad

Background: A homeopathic potency is usually given to the nursing mother for the treatment of her baby. Potencies above 12 CH cross the Avogadro number and are, therefore, too dilute to contain any original drug molecules. A potency is thought to be specifically structured water carrying the imprint of original drug molecules. It may convert the water structure in the body of the mother and through her milk reach the suckling baby. Using a toad model we have recently demonstrated that the antialcoholic effect of Nux vomica 200 CH could be transferred from one group of toads to another through capillary water which carries the information of Nux vomica. Homeopathic potencies show UV spectra distinct from its diluent medium of aquous ethanol. Does a potency remain effective even after passage through a living body? Objectives: To demonstrate that a potency effect can be transferred through the body of a live toad to other groups of toads connected through water to the live toad. Further, we want to see whether the UV spectra of drug solution and of water connected to the drug are similar in nature. Methods: A live toad was held vertically with one hind limb dipped in Nux vomica 200 CH solution in a beaker and another limb in distilled water in another beaker. The second beaker was connected by wet cotton threads encased in polythene tubes to 5 beakers, each of which contained adult toads in distilled water. A batch of toads was directly treated with Nux vomica 200 CH. An equal number of toads in distilled water served as the untreated control. After 30 min the control and the two batches of treated toads were kept separately in 209 mM ethanol solution. Toads, that stopped movement, were placed in supine position on a dry surface. Failure to assume a normal sitting posture within a cutoff time of 60 sec was regarded as loss of righting reflex (RR). The experiment was replicated using large number of toads. UV spectra of Nux vomica 200 CH solution and of water before and after connection with the drug were obtained. Results: The percentage of toads losing RR in the three groups of toads increased with time of exposure to 209 mM ethanol solution. The loss of RR was significantly delayed with the direct treatment group ( P < 0.001, chi square test) and the connected groups ( P < 0.01 , χ2 test ) as compared to the control. The two former groups did not differ from each other significantly. UV spectra of Nux vomica 200 CH solution were similar to that of water connected to the drug solution. Conclusion: The antialcoholic effect of Nux vomica 200 CH could be transferred through the body of a live toad to other groups of toads. The drug did not undergo denaturation during its passage through the living body. That water carries the information of original drug is further evidenced by the spectral properties of water connected to the drug solution through capillary water.

Postural Difference between the Interventions Reflecting the Concept of Mirror Therapy in Healthy Subjects

(1) Background: Mirror therapy is one of the promising interventions for the upper limb rehabilitation of stroke patients. Postural asymmetry during mirror therapy was pointed out as a possibility to influence stroke patients’ rehabilitation negatively. However, it is still difficult to find studies on the postural changes in mirror therapy concept interventions. This study compared three methods of postural differences as follows: traditional mirror therapy (mirror); displaying the real-time movement of the unaffected side on the screen above the affected side (screen); and playing a pre-recorded movement of the unaffected side on a tablet placed on a movable box where the affected hand is put inside (movable). (2) Methods: to observe a kinematic difference, we recruited 16 healthy volunteers to go through three different interventions (mirror, screen, movable). The motion capture system made observations on the postures before and during interventions, then compared and analyzed. (3) Results: while using the mirror, the sitting posture was observed to become asymmetric, and the following unique posture was observed where the target hand went further from the trunk while performing tasks. In addition, the shoulder of the target side came forward, and the difference between both elbow flexion angles was also observed. On the other hand, the screen or movable device did not cause a significant change in the sitting posture, and no additional postural differences were observed either. (4) Conclusions: mirror therapy showed a tendency to cause lateral flexion opposite the target hand, thus, creating additional postural change. However, developed methods controlled spine tilt, and enabled the keeping of the midline while sitting during the intervention.

Development of a System for Measurement on Asymmetric Sitting Posture

Sitting posture measurement system using the unstable board with accelerometer was developed. And, postural balance was assessed to determine the effect of asymmetry on sitting posture between patients with pelvic asymmetry and healthy subjects. 10 subjects (pelvic asymmetry patients:5, healthy controls:5) were participated in this study. We performed experiment under static and dynamic sitting condition. Angular variation in the anterior-posterior and left-right direction was measured in both two conditions. Also, intra class correlation coefficient was used to evaluate the reliability of the system. The value of angle of pelvic asymmetry patients was more tilted significantly to the left side than right side during static and dynamic sitting. The reliability of the system was excellent. This paper suggested that a system for measurement on asymmetric sitting posture can be utilized to provide useful information about patients with pelvic asymmetry in rehabilitation medicine. Furthermore, results from this study can be used to develop the new clinical quantitative measurement system.

Stand Up to Excite the Spine: Neuromuscular, Autonomic, and Cardiometabolic Responses During Motor Imagery in Standing vs. Sitting Posture

Motor imagery (MI) for health and performance strategies has gained interest in recent decades. Nevertheless, there are still no studies that have comprehensively investigated the physiological responses during MI, and no one questions the influence of low-level contraction on these responses. Thus, the aim of the present study was to investigate the neuromuscular, autonomic nervous system (ANS), and cardiometabolic changes associated with an acute bout of MI practice in sitting and standing condition. Twelve young healthy males (26.3 ± 4.4 years) participated in two experimental sessions (control vs. MI) consisting of two postural conditions (sitting vs. standing). ANS, hemodynamic and respiratory parameters, body sway parameters, and electromyography activity were continuously recorded, while neuromuscular parameters were recorded on the right triceps surae muscles before and after performing the postural conditions. While MI showed no effect on ANS, the standing posture increased the indices of sympathetic system activity and decreased those of the parasympathetic system (p &lt; 0.05). Moreover, MI during standing induced greater spinal excitability compared to sitting posture (p &lt; 0.05), which was accompanied with greater oxygen consumption, energy expenditure, ventilation, and lower cardiac output (p &lt; 0.05). Asking individuals to perform MI of an isometric contraction while standing allows them to mentally focus on the motor command, not challenge balance, and produce specific cardiometabolic responses. Therefore, these results provide further evidence of posture and MI-related modulation of spinal excitability with additional autonomic and cardiometabolic responses in healthy young men.