Body Tilt Research Articles

Ankle tendon electrical stimulation to enhance sensation of walking on a slope in walking-in-place

This study aimed to develop an effective VR locomotion technique for walking through virtual environments with sloped ground. Thus, this paper presents a novel method for inducing the sensation of walking on a slope in walking-in-place (WIP) using ankle tendon electrical stimulation (TES), which induces the body tilt sensation. We conducted two experiments to evaluate the effectiveness of the proposed method. In Experiment 1, we evaluated the sensation of ascending and descending slopes induced by the proposed method in a setup where electricity flows when the feet are grounded by comparing it to the sensation on a real slope. Experiment 1 demonstrated a marginally significant effect of electrical stimulation on the sensation of ascending or descending slopes. We attributed this to the short duration of ankle TES and the influence of the user’s interpretation of the ankle TES. Based on the findings, Experiment 2 was conducted in a setup where ankle TES was constantly applied. The results indicated that participants who focused on the subjective body tilt sensation elicited by TES and those unaware of the TES effect experienced an ascending sensation with an anterior ankle TES and a descending sensation with a posterior ankle TES. Conversely, those who focused on the tactile or force sensation induced by ankle TES experienced the opposite effect. Based on this finding, we have constructed an implementation guide for a WIP system that incorporates ankle TES to present the desired sensation of ascending or descending slopes in virtual environments.

A piezoelectric driven amphibious microrobot capable of fast and controllable movement

Abstract Due to its excellent adaptability to the environment and flexibility in narrow spaces, amphibious microrobots have become an important research direction recently. This study proposes an amphibious microrobot driven by piezoelectric actuators with a body length of 4.5 cm and a mass of 1.4 g. The microrobot consists of two active front legs, two passive rear legs, two caudal fins, and a support frame. Each front leg and each caudal fin are designed as structures integrated with their respective piezoelectric actuators. The microrobot has a tilted body, and the ground exerts an oblique upward impact force that makes it jump forward when its front legs swing backwards. The opposite swing of the two caudal fins generates propulsion for swimming. The components of the microrobot are manufactured based on the monolithic laminate process. The monolithic front actuator-leg and monolithic actuator-fin both emerge from a multi-layer material laminate. The support frame is designed and fabricated as a monolithic structure to improve assembly accuracy and reduce redundant assembly steps. The manufactured microrobot demonstrates its flexible and fast amphibious movements. Its maximum land walking speed reaches 15.3 cm/s and its turning speed reaches 48.2 degrees per second. The microrobot has a maximum payload capacity of 5 g moving on land. When the front legs and caudal fins work simultaneously, its underwater swimming speed reaches 9.1 cm/s, and the maximum turning speed is 20.5 degrees per second. The microrobot also confirms a maximum payload of 3 g during its underwater movement.

Tilting the balance: do balance abilities predict the body tilt illusion?

Tilting the balance: do balance abilities predict the body tilt illusion?

Sensation is Dispensable for the Maturation of the Vestibulo-ocular Reflex.

Vertebrates stabilize gaze using a neural circuit that transforms sensed instability into compensatory counter-rotation of the eyes. Sensory feedback tunes this vestibulo-ocular reflex throughout life. Gaze stabilization matures progressively, either due to similar tuning, or to a slowly developing circuit component. Here we studied the functional development of vestibulo-ocular reflex circuit components in the larval zebrafish, with and without sensation. Blind fish stabilize gaze normally, and neural responses to body tilts mature before behavior. Instead, synapses between motor neurons and the eye muscles mature with a timecourse similar to behavioral maturation. Larvae without vestibular sensory experience, but whose neuromuscular junction was mature, had a strong vestibulo-ocular reflex. Development of the neuromuscular junction, and not sensory experience, determines the rate of maturation of an ancient behavior.

Investigation of Video Ocular Counter-Roll Findings According to Head and Body Tilt Positions in Healthy Subjects.

A vestibulo-ocular reflex called the ocular counter-roll can be used to assess how well the otolith organs are functioning. The video ocular counter-roll (vOCR) test is a recent addition to the videonystagmography test battery that allows for video recording and quantitative ocular counter-roll analysis. The purpose of this study is to investigate potential discrepancies in vOCR measurements obtained from a 30° lateral head tilt in the roll plane versus measurements obtained from a 30° tilt of the head and body. Thirty otologically, and neurologically healthy subjects aged 18 to 30 (M = 23.32 years, SD = 2.66 years; 8 men, 22 women) participated in this study. Pure-tone audiometry, oculomotor tests, and vOCR evaluation were performed for all participants. The vOCR assessment was performed in 2 positions, 30° lateral head tilt, and 30° body tilt position. The degree of static vOCR eye position and vOCR asymmetry in both positions were calculated and compared. There was no statistically significant difference between the vOCR findings obtained in the right and left 30° lateral head tilt (p = 0.546) and body tilt (p = 0.114). vOCR asymmetry was determined as median (interquartile range) 0.08 (0.07) in lateral head tilt position and 0.09 (0.06) in body tilt position. The degree of static vOCR (8.75° [1.91]) detected during body tilt was statistically greater than the static vOCR (6.62 [1.69]) detected during head tilt (p < 0.001). There was no statistically significant difference in terms of ocular counter-roll asymmetry detected between head tilt and body tilt (p = 0.918). Our study shows a significant difference in the vOCR responses during head tilt and body tilt, a finding that should be considered during clinical evaluation of vestibular function. There was no significant asymmetry between the responses with either head or body tilt.

A novel noninvasive method for dynamic cerebral autoregulation monitoring based on near-field coupling

Dynamical cerebral autoregulation (dCA) is crucial for optimizing blood pressure (BP) management and enhancing the prognosis of stroke patients. This study aims to obtain detailed cerebral blood flow (CBF) based on near-field coupling (NFC) and establish a novel method for evaluating dCA comprehensively. We developed a synchronized monitoring system of photoplethysmography-based mean arterial pressure (MAP) and NFC-based CBF. Fifteen healthy volunteers underwent dCA measurements before and after a body tilt. The multiple CBF parameters derived from NFC, along with synchronized MAP data, were used to compute the new dCA indices. Through a comparative analysis with TCD and NIRS, we studied the ability of NFC to assess dCA accurately and comprehensively. The results show that the trend in CBF changes measured by NFC before and after body tilt corresponded to the fluctuations observed in MAP. Compared to CBFV from TCD and rSO2 from NIRS, the NFC-derived parameters provide both intracranial hemodynamics and microcirculation. The dCA indices from NFC show high consistency with those from TCD, and the RFx-PVD, RFx-VEI, and RFx-HFC are the ideal indices for assessing dCA. The CAT of RFx-HFC has the largest effect size in distinguishing different dCA levels. These results demonstrate the feasibility and reliability of integrating NFC with synchronized MAP data collection to comprehensively and accurately assess dCA. It is expected to overcome the mutual constraints of existing methods in terms of time resolution, detection range and depth, and provide a new solution for continuous bedside assessment of dCA in patients with stroke.

Feasibility of superimposed supine cycling and lower body negative pressure as an effective means of prolonging exercise tolerance in individuals experiencing persisting post-concussive symptoms: Preliminary results.

To examine the feasibility, utility and safety of superimposed lower body negative pressure (LBNP) and tilt during supine cycling in individuals suffering from persisting post-concussive symptoms (PPCS). Elevenindividuals aged 17-31 (6 females/5 males) participated in two randomized separate visits, 1week apart. A ramp-incremental test was performed during both visits until volitional failure. Visits included no pressure (control) or LBNP at -40Torr (experimental) with head-up tilt at 15degrees (females) or 30degrees (males). Transcranial Doppler ultrasound was utilized to quantify middle cerebral artery velocity (MCAv), while symptom reports were filled out before and 0, 10, and 60min post-exertion. Ratings of exertion and overall condition followed similar trends for participants across both tests. The relative increase in MCAv was blunted during the experimental condition (8%) compared to control (24%), while a greater heart rate (17 beats/min) was achieved during the LBNP condition (P=0.047). Symptom severity at the 0 and 10minpost-exertion time points displayed negligible-to-small effect sizes between conditions (Wilcoxon's r<0.11). Symptom reporting was lower at the 60min post-exertion time point with these displaying a moderate effect size (Wilcoxon's r=0.31). The combination of LBNP and tilt during supine cycling did not change the participants' subjective interpretation of the exertional test but attenuated the hyperpnia-induced vasodilatory MCAv response, while also enabling participants to achieve a higher heart rate during exercise and reduced symptoms 1h later. As this protocol is safe and feasible, further research is warranted in this area for developing PPCS treatment options. HIGHLIGHTS: What is the central question of this study? What are the feasibility, safety and utility of combining head-up tilt with lower body negative pressure during supine cycling for blunting the increase in cerebral blood velocity seen during moderate-intensity exercise in individuals experiencing persisting post-concussion symptoms? What is the main finding and its importance? Although no differences were found in symptoms between conditions within the first 10min following exertion, symptom severity scores showed a clinically meaningful reduction 60min following the experimental condition compared to the non-experimental control condition.

Human proprioceptive gaze stabilization during passive body rotations underneath a fixed head

The present study explored the presence of torsional gaze-stabilization to proprioceptive neck activation in humans. Thirteen healthy subjects (6 female, mean age 25) were exposed to passive body rotations while maintaining a head-fixed, gravitationally upright, position. Participants were seated in a mechanical sled, their heads placed in a chin rest embedded in a wooden beam while wearing an eye tracker attached to the beam using strong rubber bands to ensure head stability. The body was passively rotated underneath the head both in darkness and while viewing a projected visual scene. Static torsional gaze positions were compared between the baseline position prior to the stimulation, and immediately after the final body tilt had been reached. Results showed that passive neck flexion produced ocular torsion when combined with a visual background. The eyes exhibited rotations in the opposite direction of the neck’s extension, matching a hypothetical head tilt in the same direction as the sled. This corresponded with a predicted head rotation aimed at straightening the head in relation to the body. No such response was seen during trials in darkness. Altogether, these findings suggest that proprioception may produce a predictive gaze-stabilizing response in humans.

The effect of the Pisa syndrome on balance and gait in Parkinson’s disease: a comparative study

INTRODUCTION. Pisa syndrome is a postural deformity that can lead to impaired posture control and balance in patients with Parkinson’s disease (PD), which increases the risk of injury and reduces the quality of life. AIM. To study the effect of the Pisa syndrome on postural control, balance and gait of patients with Parkinson’s disease. HYPOTHESIS. It is assumed that patients with PD with the Pisa syndrome will have specific features of postural control and balance, which must be taken into account when developing rehabilitation technologies for correcting postural disorders. MATERIALS AND METHODS. As part of the comparative study, 30 people of both sexes were examined, all study participants received levodopa drugs in an individual dosage selected by a neurologist-parkinsonologist. The subjects were divided into 2 groups of 15 people each according to the principle of the presence of the Pisa syndrome and its absence. Criteria for inclusion in the groups: voluntary informed consent of persons with PD for the study; age from 45–80 years, stage 2–4 of Hoehn-Yahr Parkinson’s disease, absence of other diseases and gross cognitive impairment. The diagnosis was carried out using the COBS Physiomed stabilometry system and the EQ-5D-3L questionnaire, a diary of falls and a dynamic gait index (DGI). The reliability of the differences was determined by the Mann-Whitney U-test. Data processing was carried out using the Statistica 10 program. RESULTS. Significant differences were revealed in the parameter of the coordination index of the Standing Balance test for the right leg and on the EQ-5D-3L scale at a significance level of p 0.05, in the group of people with PD without the Pisa syndrome, the quality of life was significantly higher, the number of falls was significantly higher in the group of people suffering from PD with the Pisa syndrome towers. DISCUSSION. Walking with a change of direction and multitasking is the most significant problem for people with PD with the Pisa syndrome, the differences between the groups are significant at a significance level of p 0.01. CONCLUSION. Patients with PD and Pisa syndrome have altered gait associated with body tilt forward, instability and decreased balance control.

Skating techniques of ladies' world-class long-distance speed skaters to shorten curved-section time during the official 3,000 m race

This study aimed to identify the factors contributing to expedited passage through curved sections in skating by analyzing centripetal acceleration and skating motions during curving in a 3,000 m race for ladies' world-class speed skating. It included 14 elite skaters participating in the ladies' 3,000 m race held during the World Cup. The recorded area consisted of the first inner curve lane. Skaters were recorded as they passed through the measurement range at the initial, middle, and final stages of the race. Three synchronized high-speed cameras were used to record skaters from the front, back, and side. From the images obtained by the high-speed camera, 21 body endpoints and 4 blade edges were digitized at 50 Hz using specialized digitizing software. Three-dimensional coordinates of the 25 points were obtained using a panning direct linear transformation technique. The stroke-averaged centripetal acceleration and kinematic parameters were calculated based on the three-dimensional coordinates of the body during the curve-skating motion. Centripetal acceleration had a significant effect on the curved-section time in all three race stages (initial: F = 17.19, middle: F = 23.30, final: F = 16.64) and significantly decreased as the race progressed (left: F = 9.42, right: F = 8.05). Throughout the race, the right and left shanks and the body's center of mass (CM) during the stroke were raised (shank angle: left: F = 13.62, right: F = 11.02, CM height: left: F = 21.15, right: F = 21.69). The body-tilt angle for both strokes and shank-tilt angle for the right stroke were significantly correlated with centripetal acceleration in all race stages (body-tilt: left: initial: r = 0.80, middle: r = 0.75, final: r = 0.89, right: initial: r = 0.78, middle: r = 0.84, final: r = 0.67, right shank-tilt initial: r = 0.80, middle: r = 0.77, final: r = 0.63). These results suggested that to reduce the skating time through curved sections, maintaining an inward body tilt and minimizing the decrease in centripetal acceleration even in the final race stage are crucial considerations. They also suggested that when leaning the body inward and maintaining centripetal acceleration, the right shank should be leaned inward for the right stroke and the left shank should be leaned inward for the left stroke, or the left blade should be positioned farther to the right of the CM.

Trunk muscle activation in prone plank exercises with different body tilts.

Body tilt changes could affect the intensity/difficulty of core stability exercises, but there is still a lack of knowledge about its impact. To analyse the trunk muscles activation during prone plank exercises at different body tilts. Twenty-four young adults who performed recreational gymnastic activities participated in this study. Electromyography activity of the rectus abdominis (RA), external oblique (EO), internal oblique (IO) and erector spinae (ES) was recorded during the performance of six variations of the prone plank exercise (planking with feet supported on the ground [conventional horizontal position] and planking with feet supported on wall bars at five different heights increasing the angle tilt) and an inverted position exercise. The RA, EO and IO activation in all prone plank variations were higher than those observed in the conventional prone plank. In addition, the coefficient of variation of the muscle activation increased with the declination angle, reaching the highest values in the inverted position for the RA and ES muscles. The results seem to indicate that the body tilt variation could be used as an easy and inexpensive strategy for modulating the neuromuscular demands and the motor control challenge during planking exercises.

Accurate and Efficient Sitting Posture Recognition and Human‐Machine Interaction Device Based on Fabric Pressure Sensor Array and Neural Network

AbstractThis article presents a novel approach to interact with users through posture recognition, leveraging its advantages of convenience and real‐time feedback to enhance user engagement and personalized experiences. In contrast to traditional methods that rely on camera‐based posture detection, this study proposes a deep learning‐based framework for posture recognition by classifying the distribution of body pressure under different sitting positions. The system integrates a large‐area, highly flexible fabric pressure sensor array into the chair, which collects data on posture‐specific pressure patterns for training and identification purposes. A deep learning algorithm, specifically the LeNet architecture, is employed to classify 49 different sitting positions based on angular variations, including body tilt to the left or right, standard posture, and forward or backward leaning. The proposed approach achieves an impressive accuracy rate of 99.86%. Furthermore, the application of this posture recognition system in VR devices enables intelligent chair control for VR games. This research provides strong support for future advancements in chair design and human‐computer interaction technologies, enhancing ergonomic designs in various domains such as automotive seats, office chairs, and medical seating, while simultaneously improving user comfort and well‐being.

Some aspects of mechanical stability of centuries-old &lt;i&gt;Pinus pinea&lt;/i&gt; L. trees growing in the Crimea

The paper considers the issues of assessing the mechanical stability and accident rate of the Italian pine, using the example of a 120 year-old tree growing in the conditions of the recreationally loaded territory of the A.P. Chekhov House-Museum in the city of Yalta, Republic of Crimea. It was found that the viability of the studied plant is 1 point – this is a healthy plant without damage to the trunk and crown. Biomechanical studies were carried out: the aboveground phytomass of the trunk of the tree under study and the main skeletal branches with needles were calculated, the physico-mechanical properties of tissues were determined and model calculations of the mechanical stability of the tree were performed. It was found that the dimensions of the main skeletal branches are separate independent trees, and the calculated weight is an additional static load on the trunk and under the action of a dynamic factor, which additionally reduces the critical load by ~ 20% and increases the accident rate of the entire tree. A large angle of inclination, taking into account the length of the branches, also increases the degree of accident. As a result, there is a shift in the center of mass and a tilt of the entire body with a high probability of falling out of the tree with the slab. To reduce the accident rate of a tree, it is necessary to trim the main branches and reduce the load on the trunk, taking into account the center of mass, and if it is impossible to carry out the necessary trimming, it is necessary to fix dangerous skeletal branches to metal structures.

Synthesis of an electromechanical system of body tilt and recuperation of vibration energy for a high-speed electric train

This paper considers issues related to the undercarriage system of a high-speed electric train with body inclination and a vibration recovery system. The main suspension systems of the electric train body, which are currently used, were investigated. The existing shock absorption systems and alternative approaches and solutions for increasing the speed characteristics of electric rolling stock have been highlighted. A basic problem of these suspension systems was put forward, which is the lack of the possibility of recovery of oscillations, as well as the complexity of systems for tilting the body. The main dimensional and power parameters of the proposed promising shock absorber are presented. The characteristics of basic parameters of the electromechanical shock absorber were compared with those of a pneumatic spring shock absorber. A simulation model of a high-speed electric train with an electromechanical shock absorber was built in the MATLAB Simulink environment. The main units of the simulation model were defined and described, owing to which it is possible to simulate the inclination of the body to a given angle and the simulation of vibration energy recovery. Based on the results of simulating the operation of an electromechanical shock absorber as part of the undercarriage of the electric locomotive, it was determined that the synthesis of this system makes it possible to tilt the body by 5 degrees in 2 seconds. It is also stated that the proposed system makes it possible to reduce the vibrations of the electric train body by 2 times, and to recover 84 W/h of vibration energy. The body tilt results are predetermined by the speed of the mechanism due to the absence of a compressor set used in the pneumatic system. The scope of application of the vibration damper also includes the automotive field, subject to additional research into the form, amplitude of road surface vibrations and changes in overall parameters in accordance with the requirements

Different Biomechanics in Football Shooting Using Inside and Instep Kick

This research purposes were examinedthe differences in shooting accuracy using inside and instep kicks and observe differences in kick movements based on biomechanical variables. Twelve professional football players shot using inside and instep kicks on circular hops targets, shooting motions were recorded using a camera at 1000 frames per second. The kinematics during the swing phase and the impact phase with the ball producing the ball’s trajectory were analyzed. Independent t-test used to compare shooting using inside and instep kick. The results showed that there was a significant difference in shooting accuracy using inside and instep kick (tcount = 3.317, p = 0.003) with a effect size large (Cohen’s d = 1.35). When observing the movements, there were significant differences in backswing knee angle (p=0.024), frontswing knee angle (p=0.034), shoulder tilt angle (p=0.045), ball bearing foot placement (p=0.019), and inclination angle of pedestal foot(p = 0.000), while other biomechanical variables showed no significant difference (p &amp;gt; 0.05). This research concludes that accurate shooting movement is achieved using inside kicks, caused by the backswing and frontswing knee angles, body tilt, and the placement and angle of the pedestal foot.

The Effect of Roll Circular Vection on Roll Tilt Postural Responses and Roll Subjective Postural Horizontal of Healthy Normal Subjects.

Background: Falls and related injuries are critical issues in several disease states, as well as aging, especially when interactions between vestibular and visual sensory inputs are involved. Slow support surface tilt (0.6 deg/s) followed by subjective postural horizontal (SPH) assessments have been proposed as a viable method for assessing otolith contributions to balance control. Previous assessments of perceived body alignment to vertical, including subjective visual vertical, have suggested that visual inputs are weighted more when vestibular information is near the threshold and less reliable during slow body tilt. To date, no studies have examined the influence of visual stimuli on slow roll-tilt postural responses and the SPH. Therefore, this study investigated how dynamic visual cues, in the form of circular vection (CV), influence postural responses and the perception of the horizontal during and after support surface tilt. Methods: Ten healthy young adults (6 female, mean age 23) wore a head-mounted display while standing on a tilting platform. Participants were asked to remain upright for 30 s, during which (1) the visual scene rotated, inducing roll CV clockwise (CW) or counter-clockwise (CCW) at 60°/s; (2) the platform only (PO) rotated in roll to test SPH (0.6°/s, 2°, CW or CCW); (3) a combination of both; or (4) neither occurred. During SPH trials, participants used a hand-held device to reset the position of the platform to 0.8°/s to their perceived SPH. The angular motion of body segments was measured using pairs of light-emitting diodes mounted on the head, trunk and pelvis. Segment motion, prior to platform motion, was compared to that at peak body motion induced by platform motion and when SPH had been set. Results: When the support surface was tilted 2°, peak upper body tilt significantly increased for congruent CV and platform tilt and decreased at the pelvis for incongruent CV when compared to PO, leading to significant differences across body segments for congruent and incongruent conditions (p ≤ 0.008). During PO, participants' mean SPH deviated from horizontal by 0.2°. The pelvis deviated 0.2°, the trunk 0.3°, and the head 0.5° in the direction of initial platform rotation. When platform tilt and CV directions were congruent or incongruent, only head tilt at SPH reset under congruent conditions was significantly different from the PO condition (1.7° vs. 0.5°). Conclusions: Roll CV has a significant effect on phasic body responses and a less significant effect on tonic body responses to lateral tilt. The SPH of the support surface was not altered by CV. Responses during tilt demonstrated enhanced reactions for congruent and reduced reactions for incongruent CV, both different from responses to CV alone. Tonic body displacements associated with SPH were changed less than those during tilt and were only slightly larger than displacements for CV alone. This study supports the hypothesis of weighted multisensory integration during dynamic postural tasks being highly dependent on the direction of visual cues during tilt and less dependent on tonic SPH offsets. These techniques could be used to examine vestibular and visual interactions within clinical populations, particularly those with visual vertigo and dizziness.

Risk factors of proximal junctional kyphosis after surgical correction of spinal deformities caused by Scheuermann’s disease

Objective. To identify risk factors for the development of Proximal Junctional Kyphosis (PJK) in patients with Scheuermann’s kyphosis operated on using segmental instrumentation.Material and Methods. The study group consisted of 43 patients (13 females, 30 males), mean age was 17 years, and mean postoperative follow-up was 6 years. Spondylograms with a patient in a standing position performed before surgery, a week after surgery, and at the end of the follow-up period were analyzed. Radiological parameters were studied: cervical lordosis, absolute rotation angle, thoracic entry angle, T1 vertebral body tilt, neck tilt, skull tilt, thoracic kyphosis, thoracolumbar kyphosis, lumbar lordosis, vertebral and pelvic parameters (Pelvic Incidence, Pelvic Tilt, Sacral Slope), sagittal vertical axis, proximal junctional angle (PJA), and length of the posterior spinal fusion.Results. The mean PJA before surgery was 7° [3°; 8°], immediately after surgery – 10° [8°; 13°], by the end of the follow-up period – 25°[19°; 32°]. The incidence of PJK by the end of the follow-up period was 79.1 % (in 34 out of 43 patients). The initial value of thoracic kyphosis was 77° [72°; 86°], after surgery – 41° [31°; 46°], at the last examination – 43° [35°; 53°]. The inclination of the T1 vertebral body in the sagittal plane before surgery was 39° [30°; 45°], at the stages of follow-up – 33° [22°; 37°] and 39° [27°; 45°]. Some significant predictors were identified. An increase in the inclination of the T1 vertebral body (p = 0.005) by k° is associated with an increase in the risk of PJK by 1.19k [1.08k; 1.37k] times, and an increase of thoracic kyphosis by k° (p = 0.023) – by 1.12k (1.03k; 1.27k) times. The formula for preoperative predicting the likelihood of this complication is: P (PJK) = 1 - 1/(1 + exp (-23.14 + 0.26 × T1 + 0.21 × TK)), where P(PJK) is the probability of proximal junctional kyphosis; exp(z) is the exponential function to the power of z; T1 (T1 vertebral body tilt) and TK (thoracic kyphosis) are preoperative values of variables. Using ROC analysis, the threshold value for predicting PJK was determined to be 74.2 %, that is, the development of PJK was predicted in patients with a PJK probability greater than the threshold value calculated by the model formula. The predictive ability of the multivariate model was tested on the basis of the available initial data with a known final result. The prediction was correct in 41 cases out of 43.Conclusion. Using the multivariate logistic regression method, two mutually independent multiplicative indicators were determined for predicting PJK with high accuracy (sensitivity 94.1 %, specificity 100.0 %) – inclination of the T1 vertebral body and thoracic kyphosis.

Hypogravity modeling of upper extremities: an investigation of manual handling in the workplace.

Experiments on the lower limbs are the only approaches being used to study how hypogravity (HG) (0 < g < 1, e.g., Moon: 1/6g, Mars: 3/8g) affects human movement. The goal of this study was to expand this field experimentally by investigating the effect of HG on the upper extremities during one-handed manual handling tasks in a sitting posture: static weight holding with an outstretched arm, and slow repetitive weight lifting and lowering motions. The hypothesis was that while completing static and dynamic tasks with elements of repetition in HG, the upper body's tilt (angle regarding the vertical axis) would change differently from Earth's gravity. Specifically, upper arm and spine angles, joint torques, and forces were investigated. Twenty-four healthy participants aged 33.6 ± 8.2 years were involved in the trial. Joint angles were examined using vision-based 3D motion analysis. According to this investigation, there is a correlation between a body tilting backward and a gravity level reduction (p < 0.01). Thus, HG causes postural deviation, and this shows that workplace design must be adapted according to the level of gravity to promote comfortable and balanced body alignment, minimizing stress on muscles and joints. To lower the risk of musculoskeletal disorders (MSDs), enhance overall performance, and increase job satisfaction, proper support systems and restrictions for sitting positions should be taken into account, concerning different levels of gravity.

Study of the stress-strain state of the posterior lumbar fusion models in case of normal indicators of the sagittal balance of the spine and pelvis

Background. Patients suffering from hip-spine syndrome with significant changes in the hip joint complain of pain in the lumbar spine in 21.2–49.4 % of cases. After performing lumbar fusion, the mobility of the pelvis decreases, which leads to an increased risk of dislocations and the development of impingement after hip arthroplasty that is the cause for repeated surgical interventions. Goal: to study the stress distribution in the models of posterior lumbar fusion in case of normal values of the sagittal contour of the spine and lumbar lordosis. Materials and methods. A finite-element model has been developed reflecting the condition that occurs in the combined course of degenerative diseases of the lumbar spine and hip joint and is characterized by normal lordosis of 40º and forward body tilt due to flexion contracture in the hip joints. The following options were modeled: 1 — posterior fusion of the L4-L5 vertebrae using a transpedicular structure with 4 screws and an interbody support; 2 — posterior fusion of the L3-L4-L5 vertebrae using a transpedicular construction with 6 screws; 3 — posterior fusion of L1-L5 vertebrae using a transpedicular structure with 10 screws. When conducting the research, the values of stresses in the Th1-L5 vertebrae, on the screws and rods of the transpedicular structure were studied. Results. Posterior fusion with a transpedicular construction on two L4-L5 vertebrae leads to the occurrence of maximum stresses in vertebral bodies of the lumbar spine, especially L4-L5. The lowest stresses in the lumbar vertebral bodies can be obtained when the transpedicular structure is applied to all 5 vertebrae. The use of all options for posterior fusion, except for the 4-screw scheme, allows to reduce the stress in the vertebral arches of the lumbar spine below the level of the normal spine model, except for the L1 vertebra. This leads to an increase in the level of stress from the Th6 to Th12 vertebrae. The construction placed on all 5 vertebrae ensures the lowest level of stress in the arches of thoracic vertebrae. The construction placed on all the vertebrae of the lumbar spine provides a minimum level of stress in the bone tissue around the fixing screws. Reducing the length of fixation leads to a significant increase in stress in these zones. With all types of installation of the transpedicular construction, the values of the stresses on the screws in the L3-L5 vertebrae are comparable. When using the design for 5 vertebrae of the lumbar spine, the locking screws in the L1 and L2 vertebrae will experience significant loads, which, accordingly, will cause significant stress in them. The maximum level of stress in the rods occurs when two L4-L5 vertebrae are instrumented, the minimum is when the structure is placed on all five vertebrae of the lumbar spine. Conclusions. Given the stress distribution, the length of fixation plays an important role: the longer the length of fixation, the lower the stress level, both in the bone elements of the model and in the elements of metal structures.

The Influence of Balance Training on Regulation of Postural Balance in Physically Active Girls

The aim of the work was to study the influence of balance training on the regulation of the balance of the monosupport posture of young physically active girls (n = 26, 17–21 years old). For 10 weeks (3 times a week), 13 girls trained according to the program of training the ability to maintain balance in postures on unstable (balance-simulators) and supports limited in area, and 13 girls made up the “Control”. The stability of the monosupport posture was analyzed by the speed and area of fluctuations in the common center of pressure (COP) in static (in a stance on a fixed stabiloplatform with open (OE) and closed (CE) eyes) and semi-dynamic conditions (in a stance at low h = 12 cm with OE and CE and high h = 30 cm see-saw with CE). Strength abilities of the thigh muscles and extensibility of the calf muscles were recorded using functional tests. Proprioceptive sensitivity was defined as an reproduction error of the tilt of the straight body in the ankle joint. Compared with the “Control” group, the trained girls showed an significant increase in the strength endurance of the hip extensors and flexors, the accuracy of reproduction of the inclination of the vertical body, as well as the stability of the monosupport posture in static and semi-dynamic positions only with closed eyes. Effect size of the balance-training was greatest in improving the postural stability on the see-saw with CE. The suggested mechanisms for improving postural stability are an increase in the strength abilities of the leg muscles and the specific proprioceptive sensitivity of the postural system.