Center Of Pressure Displacement Research Articles

Effects of passive ankle exoskeletons on neuromuscular function during exaggerated standing sway

Effects of passive ankle exoskeletons on neuromuscular function during exaggerated standing sway

The effect of Tai Chi lower extremity exercise on the balance control of older adults in assistant living communities

BackgroundAlthough Tai Chi (TC) is an evidence-based fall prevention training for older adults, its effective movements remain unclear, which may limit the practice of TC. The purpose of this study was to compare the effectiveness of TC lower extremity exercise (TC LEE), the 8-form Tai Chi (8-form TC), and a stretching control intervention for improving balance and functional mobility among older adults.MethodsThis was a randomized controlled trial. A total of 102 participants (79 ± 6 years old) were recruited from assisted living facilities. All participants were randomly assigned to the TC LEE (n = 40), 8-form TC (n = 31), and stretching (n = 31) groups in which they received the respective interventions for 16 weeks. The Berg Balance Scale (BBS), Timed Up and Go (TUG) test, and center of pressure (COP) measurements during quiet stance were collected prior to and following the 16-week interventions. Comparisons on all measurements were conducted among all groups.ResultsSignificant improvements were found in BBS (P = 0.002), TUG test (P = 0.001), root mean square amplitude of COP displacement in the anterior–posterior (P = 0.001) and medial–lateral (P = 0.001) directions, and average COP speed in the anterior–posterior (P = 0.001) and medial–lateral (P = 0.001) directions after training in the TC intervention groups compared with the stretching group. The upper limit of the 95% confidence interval (CI) of differences in change scores on the BBS (-0.8 – 1.3 points) between the TC LEE group and the 8-form TC group was within equivalence margins (1.8 points), while the upper limit of the 95% CI of differences in change scores on the TUG test (0.1 – 2.1 s) exceeded the equivalence margin (0.7 s) with the TC LEE group having the larger change scores.ConclusionTC LEE can improve balance and functional mobility in older adults, and may have greater effect than the 8-form TC on improving functional mobility as measured by the TUG test.Trial registrationChiCTR2300070600 retrospectively registered.

Shoe choice may affect fencing lunge attack performance.

The purpose of this study was to investigate the differences in attack time and lower limb biomechanics when performing fencing lunge with fencing shoes (FS) and commonly used court shoes (CS). Additionally, the study aimed to evaluate whether fencing shoes with a heel cup (FSH) could reduce lower limb impact. Thirteen female collegiate fencers who had participated in national-level competitions were recruited for this study. Participants performed the lunge on a human-shaped target while wearing FS, FSH, or CS in a randomized order. Biomechanical data were collected using a 3D motion analysis system synchronized with a force plate. A signal light, and an accelerometer were attached to the target's head to initiate lunge movement and detect hit moment for calculating attack time. Attack time was significantly shorter when wearing FS (0.92 ± 0.05s) and FSH (0.93 ± 0.07s) compared to CS (0.96 ± 0.06s). The maximum angular velocity of ankle plantarflexion in rear foot push-off phase was significantly slower when wearing FS and FSH than when wearing CS. The maximum knee posterior shear force, maximum knee flexion moment, and maximum ankle medial shear force during the front foot step phase were significantly greater when wearing FS than when wearing CS. These forces were significantly reduced or nearly significantly reduced when wearing FSH, and there were no significant differences compared to wearing CS. The maximum ankle medial shear force during the push-off phase in rear foot was the greatest when wearing FS but decreased significantly when using FSH. However, this force was still greater than when wearing CS. Wearing FS resulted in a higher loading rate (LR) on the front foot. This LR was reduced when a heel cup was used but still remained higher than when wearing CS. There were no significant differences in the forward extension of body, maximum ground reaction force, or center of pressure displacement during front foot step and rear foot push-off phases among the three shoe conditions. Wearing FS can enhance lunge performance, and the use of a heel cup can effectively reduce lower limb impact.

Salivary cardiac-enriched FHL2-interacting protein is associated with higher diastolic-to-systolic-blood pressure ratio, sedentary time and center of pressure displacement in healthy 7-9 years old school-children.

Cardiac-enriched FHL2-interacting protein (CEFIP) is a recently identified protein, first found in the z-disc of striated muscles, and related to cardiovascular diseases. Our objectives are: 1) to quantify CEFIP in saliva in healthy 7-9 years old school-children; and 2) to assess the associations of salivary CEFIP concentration and blood pressure, physical (in)activity and physical fitness in these children. A total of 72 children (7.6 ± 0.3 years) were included in the study, recruited in primary schools in Girona (Spain). A sandwich enzyme-linked immunosorbent assay was used (abx506878; Abbexa, United Kingdom) to quantify CEFIP in saliva. Anthropometric evaluation was performed [body mass, height and body mass index (BMI)]. Systolic and diastolic blood pressure were measured by means of an electronic oscillometer and the diastolic-to-systolic blood pressure ratio (D/S BP ratio) was calculated. Physical (in)activity [sedentary time and time spent in physical activity (PA)] were assessed by means of a triaxial Actigraph GT3X accelerometer (Actigraph, Pensacola, FL, USA) that children were instructed to wear for 24h during 7 conssecutive days. Finally, physical fitness (speed and agility, explosive power of legs, handgrip strength, flexibility and balance) were assessed through validated and standardized testing batteries. CEFIP was easily detected and measured in all saliva samples (mean concentration: 0.6 ± 0.2 pg/ml). Salivary CEFIP was positively associated with D/S BP ratio (r=0.305, p=0.010) and sedentary time (r=0.317, p=0.012), but negatively associated with PA in 7-9 years old school-children (r=-0.350, p=0.002). Furthermore, salivary CEFIP was related to lower level of balance i.e., higher center of pressure (CoP) displacement in these children (r=0.411, p<0.001). The associations of salivary CEFIP with D/S BP ratio (Beta=0.349, p=0.004), sedentary time (Beta=0.354, p=0.009) and CoP displacement (Beta=0.401, p=0.001), were maintained significant after adjustment for potential confounding variables such as age, gender and BMI in linear regression analyses. CEFIP can be easily assessed in saliva as a promising biomarker associated with cardiovascular health in 7-9 years old school-children. Interestingly, higher salivary CEFIP concentration was related to higher D/S BP ratio, more sedentary time and higher CoP displacement i.e., lower level of balance in these children.

Influences of cognitive load on center of pressure trajectory of young male adults with excess weight during gait initiation.

Introduction: Falls and fall-related injuries in young male adults with excess weight are closely related to an increased cognitive load. Previous research mainly focuses on analyzing the postural control status of these populations performing cognitive tasks while stabilized walking progress but overlooked a specific period of walking known as gait initiation (GI). It is yet unknown the influences of cognitive load on this population's postural control status during GI. Objective: This study aimed to determine the influences of cognitive load on the center of pressure (CoP) trajectory of young male adults with excess weight during GI. Design: A controlled laboratory study. Methods: Thirty-six male undergraduate students were recruited and divided into normal-weight, overweight, and obese groups based on their body mass index (BMI). Participants' CoP parameters during GI under single and dual-task conditions were collected by two force platforms. A mixed ANOVA was utilized to detect significant differences. Results: Compared with the normal-weight group, the obese group showed significant changes in the duration and CoP parameters during sub-phases of GI, mainly reflecting prolonged duration, increased CoP path length, higher mediolateral CoP displacement amplitude, and decreased velocity of anteroposterior CoP displacement. During GI with 1-back task, significantly increased mediolateral CoP displacement amplitude occurred in the obese group. During GI with 2-back task, the obese group had increased CoP path length, higher mediolateral CoP displacement amplitude, as well as a decreased velocity of CoP displacement. Conclusion: Based on the changes in CoP parameters during GI with cognitive tasks, young male adults with excess weight, mainly obese ones, have compromised postural stability. During GI with a difficult cognitive task, obese young male adults are more susceptible to deterioration in their lateral postural balance. These findings indicate that the increased cognitive load could exacerbate obese young male adults' postural control difficulty during GI under dual-task conditions, putting them at a higher risk of experiencing incidents of falls. Based on these findings, we offer suggestions for therapists to intervene with these young male adults to ensure their safety of GI.

Kinesiotaping Is Not Better Than a Placebo: Kinesiotaping for Postural Control in Anterior Cruciate Ligament-Reconstructed Patients-A Randomized Controlled Trial.

The primary aim of this study was to investigate the immediate and delayed effects of kinesiotape (KT) on postural control and patient-reported outcome measures under challenging conditions in individuals with anterior cruciate ligament reconstructions. Thirty-two anterior cruciate ligament-reconstructed patients for whom 6months had passed since their operation were randomly assigned to either the KT (n = 16, aged 21.8 [5.5]y) or the placebo KT (n = 16, aged 24.0 [5.1]y) groups. Initially, both groups stood barefoot on a force platform while performing postural tasks in 4 randomized conditions (eyes open, eyes closed, cognitive task, and foam). Before the experiment, patients would bring the 4 conditions, which were written on folded papers, one by one, and in this way, the order of conditions for the examiners was determined. The patients' evaluations were conducted immediately and 48hours after KT application. Postural control measures, with area and displacement of the center of pressure (CoP) in anterior-posterior and medial-lateral directions, and mean total velocity displacement of CoP (MVELO CoP) served as dependent variables. In addition, the International Knee Documentation Committee score was measured pretreatment and 48hours posttreatment. Significant group-by-time interactions were observed for displacement of COP in medial-lateral direction (P = .002) and MVELO CoP (P = .034). MVELO CoP significantly decreased (mean difference = 0.60, P = .009) immediately after KT application compared with preapplication measures. In the placebo group, a statistically significant decrease in MVELO CoP (mean difference = 0.869, P = .001) was observed at 48hours post-KT compared with preapplication values. International Knee Documentation Committee scores significantly improved at 48hours post-KT application in both groups (P < .05). Though observed at different time points, both KT (immediately after the intervention) and placebo KT (48h after the intervention) were found to improve postural control measures. It appears that the changes in postural control may be more related to proprioceptive enhancement due to KT rather than the specific KT pattern.

Dynamics of Center of Pressure Trajectory in Gait: Unilateral Transfemoral Amputees Versus Non-Disabled Individuals.

The primary goal of rehabilitation for individuals with lower limb amputation, particularly those with unilateral transfemoral amputation (uTFA), is to restore their ability to walk independently. Effective control of the center of pressure (COP) during gait is vital for maintaining balance and stability, yet it poses a significant challenge for individuals with uTFA. This study aims to study the COP during gait in individuals with uTFA and elucidate their unique compensatory strategies. This study involved 12 uTFA participants and age-matched non-disabled controls, with gait and COP trajectory data collected using an instrumented treadmill. Gait and COP parameters between the control limb (CL), prosthetic limb (PL), and intact limb (IL) were compared. Notably, the mediolateral displacement of COP in PL exhibited significant lateral displacement compared to the CL from 30% to 60% of the stance. In 20% to 45% of the stance, the COP forward speed of PL was significantly higher than that of the IL. Furthermore, during the initial 20% of the stance, the vertical ground reaction force of PL was significantly lower than that of IL. Additionally, individuals with uTFA exhibited a distinct gait pattern with altered duration of loading response, single limb support, pre-swing and swing phases, and step time. These findings indicate the adaptability of individuals with uTFA in weight transfer, balance control, and pressure distribution on gait stability. In conclusion, this study provides valuable insights into the unique gait dynamics and balance strategies of uTFA patients, highlighting the importance of optimizing prosthetic design, alignment procedures, and rehabilitation programs to enhance gait patterns and reduce the risk of injuries due to compensatory movements.

Gait initiation in Parkinson's disease: comparison of timing and displacement during anticipatory postural adjustments as a function of motor severity and apathy in a large cohort

IntroductionGait initiation is preceded by three anticipatory postural adjustment (APA) phases. In Parkinson's disease (PD) generated force, displacement and timing during APA differ from healthy controls. APA might be influenced by disease status, weight or emotion. It is unknown how motor severity, disease duration or presence of apathy influences APA timing and displacement. MethodsWe included 99 people with PD and 50 healthy controls (HC) to perform five gait initiation trials following an auditory cue. Force plates measured timing and center of pressure (CoP) displacement during APA phases. ResultsTime to gait initiation (tGI) was higher in the PD group (p < 0.001, t = 2.74, 95%CI (0.008, 0.066)). The first two APA phases (APA1 and APA2a) lasted longer in PD (respectively p < 0.001, t = 3.87, 95%CI (0.091, 0.28) and p < 0.001, t = 4.1, 95%CI (0.031, 0.091)). Mean CoP displacement, variability in timing and displacement did not differ. A multiple regression model was used to determine if clinical variables were related to gait initiation parameters. tGI was predicted by age (p < 0.001) and weight (p = 0.005). The duration of APA1 was predicted by weight (p = 0.006) and APA2a by age (p < 0.001). Variability in duration of the locomotor phase (LOC) was predicted by age (p < 0.001). ConclusiontGI and initial APA phases are longer in PD than in HC. There are no significant differences in variability of timing or displacement between the two groups. Gait initiation parameters are independent of disease duration, motor severity, medication usage or apathy in PD. Our findings suggest that cueing does not speed up gait initiation but reduces variability.

The static balance ability on soft and hard support surfaces in older adults with mild cognitive impairment

Objective This study aimed to assess the static balance ability of the older adults with mild cognitive impairment (MCI) while standing on soft and hard support surfaces. Methods Forty older adults participated in this study (21 in the MCI group and 19 in the control group). Participants were required to perform balance tests under four conditions of standing: standing on a hard support surface with eyes open, standing on a soft support surface with eyes open, standing on a hard support surface with eyes closed, and standing on a soft support surface with eyes closed. Each test was measured in three trials and each trial lasted 30 seconds. Participants were asked to take off their shoes and place their feet in a parallel position with a 20-centimeter distance for bipedal support. The trajectories of the center of pressure (COP) were measured using a Kistler force platform with a frequency of 1000 Hz to assess balance while standing in both groups, with larger COP trajectories indicating poorer static balance in older adults. Results With eyes open, the displacement of COP in the anterior-posterior direction(D-ap) (hard support surface: P = 0.003) and the 95% confidence ellipse area(95%AREA-CE) (soft support surface: P = 0.001, hard support surface: P &lt; 0.001) of the COP in the MCI group standing on hard and soft support surfaces were significantly larger than the control group. The 95%AREA-CE (P &lt; 0.001) of the COP in the MCI group on the soft support surface was significantly larger than on the hard support surface. With eyes closed, the root mean square distance(RDIST), root mean square distance-ML(RDISTml), and 95%AREA-CE of the COP were no significant between-group differences when standing on hard support surfaces. However, the RDIST (P = 0.014), RDISTml (P = 0.014), and 95%AREA-CE (P = 0.001) of the COP in the MCI group on the soft support surfaces were significantly larger than the control group. The 95%AREA-CE (P &lt; 0.001), RDIST (P &lt; 0.001), and RDISTml (P &lt; 0.001) of the COP in the MCI group on the soft support surface were significantly larger than the hard support surface. Conclusion With eyes open, the older adults with MCI showed poorer static balance ability compared to the older adults with normal cognition on soft and hard support surfaces. With eyes closed, the older adults with MCI showed poorer static balance on soft support surfaces, but no differences on hard support surfaces compared with the older adults with normal cognition. With eyes open and closed, the older adults with MCI showed poorer static balance on soft support surfaces as compared to hard support surfaces.

The Relationship between Balance Confidence and Center of Pressure in Lower-Limb Prosthesis Users

Background: Agreement between the activities-specific balance confidence scale (ABC) and center of pressure (CoP) in prosthesis users is still very much unknown. The purpose of this study was to investigate the agreement between ABC and CoP in lower-limb prosthesis users. Methods: Twenty-one individuals with lower-limb prostheses were recruited. Participants were provided with the ABC scale and performed static balance tasks during eyes opened (EO) and eyes closed (EC) conditions whilst standing on a force platform. Pearson product moment coefficients between CoP displacements and ABC scores were performed. Participants were also stratified by those who had better (≥80 on ABC scale) and less (&lt;80 on ABC scale) perceived balance confidence. Displacement was compared using an independent t-test with Cohen’s d to estimate effect size with alpha set at 0.05 for these tests. Results: There was a significant inverse moderate relationship between eyes opened displacement (EOD) (18.3 ± 12.5 cm) and ABC (75.1 ± 18.3%), r = (19)−0.58, p = 0.006, as well as eyes closed displacement (ECD) (37.7 ± 22.1 cm) and ABC, r = (19)−0.56, p = 0.008. No significant difference in EOD (t(19) = 1.36, p = 0.189, d = 0.61) and ECD (t(19) = 1.47, p = 0.156, d = 0.66) was seen between those with greater and less balance confidence. Conclusions: Self-report and performance-based balance outcome measures are recommended when assessing lower-limb prostheses users.

Interactive Game-Based Platform System for Assessing and Improving Posture Control in the Elderly.

Inadequate response to balance perturbations lead to posture instability in the elderly. The fall risks are increased by a reduced capacity to control the center of pressure (COP) displacement within the safety limit of the supporting base. This study developed an interactive evaluation and training platform. The system incorporated a computerized program with instantaneous force plate evaluation. Ten young subjects underwent a baseline evaluation and twenty-nine community-dwelling elderly received pre- and post-intervention testing. The ability to reach the stability limit was assessed by measuring the maximum voluntary excursion of the COP in anterior-posterior and medial-lateral directions. Functional mobility tests including Berg Balance Scale, Timed-Up-and-Go and functional reach were used as functional outcomes. The experimental group (n = 15) received a 40 min intervention three times a week for six weeks. The interactive game-based training focused on multi-directional weight shifting by tracing a COPcontrolled target to challenge an individual's stability limit. The control group (n = 14) maintained daily activities as usual. The young group revealed a superior COP displacement through active ankle control than the elderly, especially in the anterior-posterior direction. The experimental group improved their COP displacement control more in the medial-lateral direction due to the predominant side-to-side gameplay movement. The functional outcome measures were also significantly improved after training. Using the COPcontrolled game-based program, the stability limit was challenged to facilitate dynamic posture control by an incremental increase in self-initiated perturbations. The platform system could assist in transferring the immediate training effects into daily functional mobility in the elderly.

Dynamic postural control in women athletes with and without nonspecific low back pain with high and low pain-related anxiety- A case-control study

BackgroundLow back pain is common among athletes and it has been shown that postural control is altered in the general population with nonspecific low back pain (NSLBP). Psychological factors may also predispose individuals to risk of altered postural control. Dynamic postural control is essential to the performance of athletes. This study aimed to compare the dynamic postural control between women athletes with and without NSLBP with high and low pain-related anxiety.MethodsForty-five female athletes (15 NSLBP with high pain-related anxiety, 15 NSLBP with low pain-related anxiety, and 15 healthy (control)) were included. Pain-related anxiety was assessed using the Pain Anxiety Symptom Scale-20 (PASS-20). Based on the cut-off score of 30 for the total score of PASS-20, NSLBP patients were classified into two groups of low and high pain-related anxiety. Participants performed double-leg vertical drop jump (DVJ) and single-leg vertical jump (SVJ) tests on a Kistler force plate (type 9260AA6, Kistler Instruments Inc, Switzerland). The total root mean square (RMS) of the center of pressure (COP), COP displacement in the anteroposterior (AP), and mediolateral (ML) directions, COP mean velocity, and time to stabilization (TTS) in vertical, AP, and total directions were extracted from COP and ground reaction force data using MATLAB software. One-way Analysis of variance (ANOVA) and Welch’s ANOVA were employed to compare the groups. In case of significant findings, post hoc tests were performed.ResultsThe results showed that during DJV, athletes with high pain-related anxiety had significantly greater TTS in all total, AP, and ML directions than other groups (P < 0.05). Also, the control group showed greater total RMS distance during DJV than either NSLBP group. However, no significant differences in TTS and COP parameters were found between the groups during SVJ (P > 0.05).ConclusionsThe findings suggest that pain-related anxiety may contribute to athletes’ postural control strategies. Therefore, it is important to consider the level of pain-related anxiety during planning postural control exercises for women athletes with NSLBP.

Functional relation between postural sway and saccadic eye movements is strong and not altered by moving visual environment and concomitant memory task

We investigated whether the adaptation of postural control to perform saccadic tasks is still maintained in challenging situations such as when the posture is challenged with a large movement of the moving room and with the addition of a second perturbation as a visual task of memorization. Thirty young adults (20.0 ± 1.3 years) were randomly assigned to the control and experimental groups. Participants stood upright on a force plate inside a moving room wearing eye-tracking. The room moved back and forth (anterior–posterior direction), at low (.6 cm—first and third trials) and high (3.5 cm—second trial) amplitude, and frequency of .2 Hz. In each trial, participants performed left-right horizontal saccades on a target (1.1 Hz). The experimental group also performed a concomitant number memorization task. There were no differences between groups in the coupling between center of pressure (CoP) displacements and visual stimulus in any condition. There was also no difference in the performance of the saccadic task. In the memorization task, CoP displacements in response to the visual stimulus frequency (room motion) were not affected. The performance in the memorization task was similar between room conditions. Overall, increasing cognitive involvement by adding a working memory task does not deteriorate the postural stabilization of young adults to accomplish accurate gaze shifts. Also, it does not interfere with adaptive visual reweighting due to changes in the moving room amplitude. In conclusion, young adults are flexible in optimizing their postural control to succeed in multiple tasks even under perturbation.

External mechanical perturbations challenge postural stability in dogs.

This study aimed to explore the effect of external mechanical perturbations on postural stability (PS) in dogs using the body center of pressure (COP). Thirteen sound adult dogs were included in this study. PS was tested during quiet standing on a pressure measurement plate. The conditions included a standard standing measurement and external mechanical perturbations conducted using six settings on a motorized training platform with different intensities of speed and amplitude. Measurement conditions were compared using linear mixed-effects models, followed by multiple comparisons using Sidak's alpha correction procedure. Compared with the standing measurement, external mechanical perturbations resulted in a significant increase in almost all COP parameters, indicating a challenge for the PS. Furthermore, an increase in amplitude had a greater effect than an increase in speed, whereas the combination of the highest intensities of amplitude and speed was not well tolerated by the dogs. The mediolateral COP displacement was significantly greater than the craniocaudal COP displacement during standing measurement and conditions with a small amplitude, whereas no significant difference was observed during settings with an increased amplitude. To the best of our knowledge, this is the first study to demonstrate the effects of a balance training device in dogs. Therefore, the intensity of the training programs on motorized platforms or similar devices can be controlled by the wobbling amplitude of the platform.

The Effects of Fatigue on the Lower Limb Biomechanics of Amateur Athletes during a Y-Balance Test.

The Y-Balance Test (YBT) is a reliable tool for assessing the dynamic balance of athletes' lower limbs. This study aimed to compare the effects of the YBT on lower limb biomechanics before and after fatigue. Sixteen adult male recreational athletes were recruited for the study, and motion capture in combination with a force plate was used to collect kinematic, dynamics, and center of pressure (COP) data of the dominant leg during YBT testing before and after fatigue. Based on the research findings, there were significant statistical differences in the distances reached during the YBT in three directions before and after fatigue. After fatigue, there is a significant decrease in the ROM of the hip and knee joints in all three directions. Also, there is a significant increase in hip joint torque in the anterior- and posterior-lateral directions, while a significant decrease in hip and ankle joint torque is observed in the posterior-medial direction. Moreover, there is an increasing trend in positive and negative joint work for the hip, knee, and ankle joints in all three directions after fatigue. The range of COP displacement also increases following fatigue. The decline in YBT scores demonstrates the detrimental impact of fatigue on the dynamic balance of the lower limbs of adult male amateur athletes. We hope that these results can provide information for athletes and coaches to better understand the effects of fatigue on the dynamic balance of lower limbs, so as to carry out targeted lower limb balance training and prevent sports injuries.

Short-Term Cast Immobilization of a Unilateral Lower Extremity and Physical Inactivity Induce Postural Instability during Standing in Healthy Young Men.

Previous studies have reported an increased postural sway after short-term unilateral lower limb movement restriction, even in healthy subjects. However, the associations of motion limitation have not been fully established. The question of whether short-term lower limb physical inactivity and movement restriction affect postural control in the upright position remains. One lower limb of each participant was fixed with a soft bandage and medical splint for 10 h while the participant sat on a manual wheelchair. The participants were instructed to stand still for 60 s under eyes-open (EO) and eyes-closed (EC) conditions. Using a single force plate signal, we measured the center of pressure (COP) signal in the horizontal plane and calculated the total, anterior-posterior (A-P), and medial-lateral (M-L) path lengths, sway area, and mean COP displacements in A-P and M-L directions. The COP sway increased and the COP position during the upright stance shifted from the fixed to the non-fixed side after cast removal, compared to before the cast application, under both EO and EC conditions. These findings indicated that 10 h of unilateral lower limb movement restriction induced postural instability and postural control asymmetry, suggesting the acute adverse effects of cast immobilization.

The effects of a 12-week yoga program on the CoP of military pilots before and after a flight emergency simulation using Biosignals Plux force platform

This study examined the effects of Ashtanga Vinyasa Yoga Supta on Center of Pressure (CoP) displacement in healthy student pilots, using the Biosignals Plux force platform, under the premise that yoga would lead to improvements in postural control responses. CoP response was analyzed by the Plux (Portugal) one-dimensional force platform. A total of 18 military pilots participated in this study. The pilots were in their Portuguese Air Force Academy course “Masters in Military Aeronautics: Aviator Pilot Specialist,” also called Tirocinium. Participants were randomly assigned to yoga classes (intervention group) or a waiting list (control group) and completed a flight emergency protocol in a flight simulator. CoP displacement was collected before and after all these maneuvers had been completed and both measures occurred before (baseline values) and after a 12-week yoga program. Although the differences observed between groups are not significant, after calculating the effect size, we can theorize that the intervention group maintains CoP displacement before and after flight and the control group has a higher CoP displacement after flight simulation. CoP information collected through noninvasive portable devices such as the Biosignals Plux force platform can relay important information quickly and easily. Knowing under what circumstances pilots are affected can then lead to development or enhancement of training strategies to improve those psychophysiological responses. In this study the effects, while not significant, are present, so it may be necessary to add more weeks of training to make the yoga program effective.

Impact of five floor coverings on the orthostatic balance of healthy subjects.

Plantar skin sensitivity contributes to the regulation of postural control and, therefore, changing the characteristics of the plantar support surface can modify this control. This study aimed at assessing the impact of five different floor coverings on the orthostatic balance in 48 healthy subjects. Static posturography was performed with eyes open or closed on a platform in a control condition (no covering) and with five different covering surfaces: foam, silicone, ethyl vinyl acetate, and two textured mats with small (height 2mm) or large pimples (7mm). The average velocity of center of pressure (CoP) displacement was the primary endpoint measure and ten other posturographic variables were assessed. Comfort and pain produced by the covering were also scored. In eyes open condition, the average velocity of CoP displacement was increased when subjects stood on the foam mat, the silicone mat, and especially the textured mat with large pimples. Several other posturographic variables showed significant changes with different types of floor coverings with eyes open. These changes were not correlated to the comfort or pain scores associated with the different surfaces. In contrast, no difference was observed compared to the control condition (no covering) with eyes closed. This study shows that adding smooth or textured floor covering can alter balance in eyes open condition. In eyes closed condition, although more disturbing for balance, healthy subjects achieved better postural adaptation, probably by mobilizing more of their proprioceptive resources. This posturographic examination procedure could, therefore, be used to assess "proprioceptive reserve" capacities in clinical practice.

Recognition of walking directional intention employed ground reaction forces and center of pressure during gait initiation

BackgroundMovement intentions are generally classified by Electroencephalogram (EEG) and have been used in gait initiation prediction. However, it is not easy to collect EEG data and practical in reality. Alternatively, ground reaction force (GRF) and the center of pressure (COP) is produced by the contact between the foot and the ground during a specific period of walking, which are the characteristics of evaluating gait performance Research questionThe study aims to use a deep learning technique to recognize the data of the COP and GRF to classify straight walking and right turn. Second, the study aims to reveal gait characteristics that could replace EEG to predict walking directional intentions MethodsTen healthy male adults were instructed to stand on the force platform and self-selected to perform three conditions: standstill, straight walking, and right turn. The onset of gait initiation was evaluated by muscle activation of the right tibialis anterior, and EEG and the COP displacement evaluated the onset of gait intention. Subsequently, GRF and COP would be treated as features to classify the gait intention in the Long Short-Term Memory (LSTM) model. ResultsThe results revealed that the onset of EEG and the COP displacement initiation were statistically significant differences between straight walking and right turn. For the classification, the average accuracy of the LSTM model with GRF and COP as features reached the highest one, 94.79 %, depending on the heel- or toe-off of the swing leg. The results indicated that gait intentions could be classified based on the GRF and COP. SignificanceThe machine learning technique of LSTM with gait parameters can recognize the gait intention of changing walking orientation. Our model and approach would be expected to provide advanced predictions, such as exoskeleton control or pedestrian traffic flow.

Ankle Strategies for Step-Aside Movement during Straight Walking.

The step-aside movement, also known as the dodging step, is a common maneuver for avoiding obstacles while walking. However, differences in neural control mechanisms and ankle strategies compared to straight walking can pose a risk of falling. This study aimed to examine the differences in tibialis anterior (TA), peroneus longus (PL), and soleus (SOL) muscle contractions, foot center of pressure (CoP) displacement, and ground reaction force (GRF) generation between step-aside movement and straight walking to understand the mechanism behind step-aside movement during walking. Twenty healthy young male participants performed straight walking and step-aside movements at comfortable walking speeds. The participants' muscle contractions, CoP displacement, and GRF were measured. The results show significant greater bilateral ankle muscle contractions during the push and loading phases of step-aside movement than during straight walking. Moreover, the CoP displacement, GRF generation mechanism, and timing differed from those observed during straight walking. These findings provide valuable insights for rehabilitation professionals in the development of clinical decisions for populations at a risk of falls and lacking gait stability.