Foam Pad Research Articles

Visual and somatosensory contributions to infant sitting postural control

There are a limited number of studies that have investigated sitting posture during infancy and the contribution of the sensory systems. The goal of this study was to examine the effects of altered visual and somatosensory signals on infant sitting postural control. Thirteen infants (mean age ± SD, 259.69 ± 16.88 days) participated in the study. Initially, a single physical therapist performed the Peabody Developmental Motor Scale to determine typical motor development. Then the child was placed onto a force platform under four randomized conditions: (a) Control (C) – sat independently on the force plate, (b) Somatosensory (SS) – Sat independently on a foam pad (low density), (c) Visual (VS) – sat independently on the force plate while the lights were turned off creating dim lighting, and (d) Combination of b and c (NVSS). Center of pressure (COP) data from both the anterior-posterior (AP) and the medial-lateral (ML) directions were acquired through the Vicon software at 240 Hz. The lights off conditions, both VS and NVSS, lead to increased Root Mean Square (RMS) and Range values in the AP direction, as well as increased Lyapunov Exponent (LyE) values in the ML direction. Altered visual information lead to greater disturbances of sitting postural control in typically developing infants than altered somatosensory information. The lights off conditions (VS and NVSS), unveiled different control mechanisms for AP and ML direction during sitting. Thus, the present findings confirm the dominance of vision during the early acquisition of a new postural accomplishment.

Foam padding in postoperative lower extremity casting: an inexpensive way to protect patients

Foam padding in postoperative lower extremity casting: an inexpensive way to protect patients

Comparison on cooling efficiency of cooling pad materials for evaporative cooling system


 
 
 
 This research aims to examine on cooling efficiency of different type natural based material as a cooling pad for evaporative cooling system. Efficiency of direct evaporative cooling system mostly depends on the cooling pad and hence, the material used in the cooling pad plays a very vital role. Here, two types of natural based materials (activated carbon foam and luffa pad) were selected to be used as cooling pad. Those materials pad are then fabricated to fit into the evaporative cooling setup. Temperature, and humidity are the most important data in this experimental analysis. The readings of these terms are taken for each type of cooling pad using data logger and also, the further calculations are done based on these readings. The material of the cooling pad and the air flow rate are varied to observe the effect on their cooling efficiency. From the analysis, the ACF cooling pad shows better cooling efficiency compared to that of luffa pad.
 
 
 

Cholinergic Pathway SNPs and Postural Control in 477 Older Adults.

Objective: To determine whether single nucleotide polymorphisms (SNPs) of the cholinergic system and quantitative parameters of postural control are associated in healthy older adults. This is a cross-sectional analysis from the TREND study.Methods: All participants performed a static postural control task for 30 s on a foam pad in semitandem stance and eyes closed. We analyzed mean power frequency (MPF), area, acceleration, jerk, and velocity from a mobile sensor worn at the lower back using a validated algorithm. Genotypes of four SNPs in genes involved in the cholinergic system (SLC5A7, CHAT, BCHE, CHRNA4) were extracted from the NeuroX chip. All participants present a normal neurological examination and a Minimental state examination score >24.Results: Four hundred and seventy seven participants were included. Mean age was 69 years, 41% were female. One SNP of the cholinergic pathway was significantly associated with a quantitative postural control parameter. The minor allele of rs6542746 in SLC5A7 was associated with lower MPF (4.04 vs. 4.22 Hz; p = 3.91 × 10-4). Moreover, the following associations showed trends toward significance: minor allele of rs6542746 in SLC5A7 with higher anteroposterior acceleration (318 vs. 287 mG; p = 0.005), and minor allele of rs3810950 in CHAT with higher mediolateral acceleration [1.77 vs. 1.65 log(mG); p = 0.03] and velocity [1.83 vs. 1.74 log(mm/s); p = 0.019]. Intraindividual occurrence of rs6542746 and rs3810950 minor alleles was dose-dependently related with lower MPF (p = 0.004).Conclusion: This observational study suggests an influence of SNPs of the cholinergic pathway on postural control in older adults.

Foam Padding in Postoperative Lower Extremity Casting: An Inexpensive Way to Protect Patients.

Although postoperative cast immobilization is routinely used in children, it is not without complications. Few studies have focused on interventions to decrease their frequency. The purpose of this study was to determine if foam padding in postoperative lower extremity casts decreased the rate of cast complications. A retrospective review of patients who underwent lower extremity casting after elective surgery at a tertiary pediatric hospital from 2006 to 2013 was conducted. Postoperative casts were classified by type (A-frame, short leg, long leg, spica) and the presence of foam. Charts were reviewed for skin complications, cast splits for apparent neurovascular deficits, cast splits for patient complaints, unplanned outpatient returns for cast-related issues, and compartment syndrome. In total, 920 patients with 2,481 casts were included. In total, 612 (24.7%) casts had foam placed during casting. The incidence of skin complications was significantly lower in A-frame casts with foam (4.5%, 5/112) than without (13.4%, 11/82) (P=0.03) and long leg casts with foam (0.9%, 2/225) than without (4.3%, 19/444) (P=0.02). Patients with static encephalopathy casted with foam had a lower incidence of skin complications (0.7%, 2/279) than those without (3.6%, 22/615) (P=0.01). There was no difference in the overall incidence of skin complications in casts with and without foam (P=0.44), short leg casts (P=0.37), and spica casts (P=0.34). Patients with skin complications (20.3±7.1 kg/m) had a higher body mass index than those without (18.9±5.4 kg/m) (P=0.04). Postoperative A-frame casts with foam (0.0%, 0/112) were split less often for apparent neurovascular deficits than those without foam (4.5%, 3/67) (P=0.05). The cast split rates for apparent neurovascular deficits in casts with and without foam (P=0.58), long leg casts (P=0.67), short leg casts (P=0.63), and spica casts (P=1.0) were comparable. The use of foam in postoperative lower extremity casting is an effective intervention to reduce the incidence of skin complications in patients with static encephalopathy, in an A-frame cast, or in a long leg cast. Level III-retrospective comparative study.

Effect of six-week intervention program on postural stability measures and muscle coactivation in senior-aged women.

ObjectiveThe objective involved the analysis of the efficiency of the Program of Movement Recreation of Elderly People (PMREP) exercise program expressed in terms of the stabilography measures and coactivation of muscles in women in the age group of 60–70 years. The assumption that was assumed stems from theoretical implications that the adequate postural stability is manifested in the decrease of the body sways measured by means of a force plate.Materials and methodsThe study involved a group of 60 females, all members of the active seniors’ association. The subjects were in the age range from 60 to 70 years. The subjects were divided into 2 groups of equal size: control and experimental. Subjects in both groups participated in the rehabilitation exercises: experimental (n=16, PMREP – twice a week/60 minutes), control (n=27, PMREP – only once a week/60 minutes).ResultsThe study demonstrated that the completion of a 6-week PMREP program resulted in a decrease in the variability and velocity as well as indicators representing center of pressure displacement measured in the feet for the exercises performed with closed eyes with subjects standing on a high foam pad located on a force plate (P=0.001). No significant changes in coactivation of the calf muscles were recorded in the subjects.ConclusionThe study concludes that a PMREP rehabilitation plan with an adequate program and frequency leads to an improvement of the vestibular system coupled with proprioception understood as an integrated process of sensor activation in the body. However, in regard to the coactivation of the muscles involved in maintaining postural stability, no significant differences have been observed.

Effect of Body Mass on Oxygenation and Intra-Abdominal Pressure When Using a Jackson Surgical Table in the Prone Position During Lumbar Surgery.

Prospective observational study. To test the hypothesis that different types of surgical frame and the patient's body mass index (BMI) can affect pulmonary compliance, intra-abdominal pressure (IAP), and oxygenation. The oxygenation index (PaO2/FiO2) and IAP are known to be associated with BMI when patients are in the supine position. However, there are few reports on the correlation between BMI, the oxygenation index, and IAP in the prone position, especially when a Jackson surgical table is used. Thirty-seven adult patients were divided into two groups according to BMI: normal-weight patients (n = 19, BMI: 18.5-24.9 kg m) and overweight patients (n = 18, BMI ≥ 25 kg m). After the induction of general anesthesia, patients were turned to the prone position onto either a Jackson surgical table (Mizuho OSI) or a general surgical table (MAQUET; foam pad, China). The patient's IAP, peak airway pressure, pulmonary dynamic compliance (Cdyn), and oxygenation index were recorded. In overweight patients, there was a greater increase in peak airway pressure and a greater decrease in Cdyn observed when a general surgical table was used compared with the Jackson surgical table. When the Jackson surgical table was used, there was a greater increase in the oxygenation index and a greater decrease in IAP. There was a significant negative correlation between the oxygenation index and BMI and a significant positive correlation between IAP and BMI in the prone position. Turning patients from the supine to the prone position during anesthesia results in an increase in the oxygenation index and a decrease in IAP. Both of these factors are dependent upon the type of surgical frame used and the patient's BMI. The reduction in IAP was particularly significant when a Jackson surgical table was used for overweight patients. 4.

Mapping the topological organisation of beta oscillations in motor cortex using MEG

The spatial topology of the human motor cortex has been well studied, particularly using functional Magnetic Resonance Imaging (fMRI) which allows spatial separation of haemodynamic responses arising from stimulation of different body parts, individual digits and even spatially separate areas of the same digit. However, the spatial organisation of electrophysiological responses, particularly neural oscillations (rhythmic changes in electrical potential across cellular assemblies) has been less well studied. Mapping the spatial signature of neural oscillations is possible using magnetoencephalography (MEG), however spatial differentiation of responses induced by movement of separate digits is a challenge, because the brain regions involved are separated by only a few millimetres. In this paper we first show, in simulation, how to optimise experimental design and beamformer spatial filtering techniques to increase the spatial specificity of MEG derived functional images. Combining this result with experimental data, we then capture the organisation of the post-movement beta band (13–30 Hz) oscillatory response to movement of digits 2 and 5 of the dominant hand, in individual subjects. By comparing these MEG results to ultra-high field (7T) fMRI, we also show significant spatial agreement between beta modulation and the blood oxygenation level dependent (BOLD) response. Our results show that, when using an optimised inverse solution and controlling subject movement (using custom fitted foam padding) the spatial resolution of MEG can be of order 3–5 mm. The method described offers exciting potential to understand better the cortical organisation of oscillations, and to probe such organisation in patient populations where those oscillations are known to be abnormal.

Relevant factors in the design of composite ballistic helmets

In this paper, the design methodology of composite ballistic helmets has been enhanced considering biomechanical requirements by means of finite element analysis. Modern combat helmets lead to a new type of non-penetrating injury, the Behind Helmet Blunt Trauma (BHBT), generated by the deformation of the inner face of the helmet, the so-called backface deformation (BFD). Current standard testing methodologies use BFD as the main measure in ballistic testing. Nonetheless, this work discusses the relationship between this mechanical parameter and the head trauma (BHBT) by studying different head injury criteria. A numerical model consisting of a helmet and a human head is developed and validated with experimental data from literature. The consequences of non-penetrating high-speed ballistic impacts upon the human head protected by an aramid combat helmet are analysed, concluding that the existing testing methodologies fail to predict many types of head injuries. The influence of other parameters like bullet velocity or head dimensions is analysed. Usually, a single-sized helmet shell is manufactured and the different sizes are adjusted by varying the foam pad thickness. However, one of the conclusions of this work is that pad thickness is critical to avoid BHBT and must be considered in the design process.

Modified device for fluid percussion injury in rodents.

Fluid percussion (FP) injury model is a popular animal model of traumatic brain injury (TBI), but still there are some issues need to be addressed. To increase the validity and reliability of this technique, we adapted the FP device using electromagnetic protractor, stainless-steel cylinder, changing pressure transducer position, and foam pads to adjust the parameters of FP pulse. Besides, the adjusted FP device is more automatic. The FP pulse is promptly measured and displayed in a graphic user interface software. The modified device resulted in reliable FP pulse. The accuracy of the pendulum leveling was improved with using the electromagnetic protractor with slots. We then collected behavioral, cognition, electrophysiological, and immunohistochemical data to verify the percussion effects in TBI mice. Lateral fluid percussion injury (FPI) or sham treatment was administered at the right frontal motorsensory region of male C57BL/6J mice. TBI mice showed evident motor, cognitive, and functional impairments, characterized by evaluation of neurological, righting, geotaxis and cliff aversion reflexes, limb asymmetrical use, rotarod running, and Morris water maze testing. The neurobehavioral damages were scaled with histopathological findings. Further, the overall firing rates and theta powers in hippocampal CA1 were significantly reduced in TBI mice compared to sham mice at Days 2 and 3 after electrode implanting. The adapted device induced effects on behavior and biology in mice that agree with existing models. These findings confirmed the validity of adjustments, and the modified device may boost the interest in TBI studies.

Effect of high-intensity perturbations during core-specific sensorimotor exercises on trunk muscle activation

Core-specific sensorimotor exercises are proven to enhance neuromuscular activity of the trunk. However, the influence of high-intensity perturbations on training efficiency is unclear within this context.Sixteen participants (29±2yrs; 175±8cm; 69±13kg) were prepared with a 12-lead bilateral trunk EMG. Warm-up on a dynamometer was followed by maximum voluntary isometric trunk (flex/ext) contraction (MVC). Next, participants performed four conditions for a one-legged stance with hip abduction on a stable surface (HA) repeated randomly on an unstable surface (HAP), on a stable surface with perturbation (HA+P), and on an unstable surface with perturbation (HAP+P). Afterwards, bird dog (BD) was performed under the same conditions (BD, BDP, BD+P, BDP+P). A foam pad under the foot (HA) or the knee (BD) was used as an unstable surface. Exercises were conducted on a moveable platform. Perturbations (ACC 50m/sec2;100ms duration;10rep.) were randomly applied in the anterior-posterior direction. The root mean square (RMS) normalized to MVC (%) was calculated (whole movement cycle). Muscles were grouped into ventral right and left (VR;VL), and dorsal right and left (DR;DL). Ventral-Dorsal and right-left ratios were calculated (two way repeated-measures ANOVA;α=0.05).Amplitudes of all muscle groups in bird dog were higher compared to hip abduction (p≤0.0001; Range: BD: 14±3% (BD;VR) to 53±4%; HA: 7±2% (HA;VR) to 16±4% (HA;DR)). EMG-RMS showed significant differences (p<0.001) between conditions and muscle groups per exercise. Interaction effects were only significant for HA (p=0.02). No significant differences were present in EMG ratios (p>0.05).Additional high-intensity perturbations during core-specific sensorimotor exercises lead to increased neuromuscular activity and therefore higher exercise intensities. However, the beneficial effects on trunk function remain unclear. Nevertheless, BD is more suitable to address trunk muscles.

Foam pad of appropriate thickness can improve diagnostic value of foam posturography in detecting postural instability

Objective: The present study investigated the effect of foam thickness on postural stability in patients with unilateral vestibular hypofunction (UVH) during foam posturography.Methods: Static and foam posturography were performed in 33 patients (UVH group) and 30 healthy subjects (control group) with eyes open (EO) and closed (EC) on firm surface and on 1–5 foam pad(s). Sway velocity (SV) of center of pressure, standing time before falling (STBF) and falls reaction were recorded and analyzed.Results: (1) SVs had an increasing tendency in both groups as the foam pads were added under EO and EC conditions. (2) STBFs, only in UVH group with EC, decreased with foam thickness increasing. (3) Significant differences in SV were found between the control and UVH group with EO (except for standing on firm surface, on 1 and 2 foam pad(s)) and with EC (all surface conditions). (4) Receiver operating characteristic curve analysis showed that the SV could better reflect the difference in postural stability between the two groups while standing on the 4 foam pads with EC.Conclusion: Our study showed that diagnostic value of foam posturography in detecting postural instability might be enhanced by using foam pad of right thickness.

Force attenuation capacity and thermophysiological wear comfort of vertically lapped nonwoven fabric

Hip-protective pads are designed to prevent hip fracture in elderly women. Two types of vertically lapped nonwoven fabrics were evaluated for suitability as materials for hip-protective pads. The force attenuation capacity of pads made from these fabrics was studied using drop impact tests, and performance relevant to thermophysiological wear comfort measured using a sweating guarded hot plate. The results indicate that vertically lapped nonwoven fabrics are suitable materials for soft hip-protective pads. They provide effective protection for the hip bone, and have similar force attenuation capacity to closed-cell foam. The inter-fibre and voids in nonwoven structures enable moisture to escape to the environment, and the experimental vertically lapped nonwoven fabric pads had significantly higher ability to transfer moisture than closed-cell foam pads.

Listeria monocytogenes persistence and transfer to cantaloupes in the packing environment is affected by surface type and cleanliness

Investigation of the 2011 U.S. listeriosis outbreak associated with consumption of contaminated cantaloupes (Cucumis melo L) revealed that transfer of Listeria monocytogenes from equipment surfaces to melons in the packing facility was a potential route of contamination. The study presented here examined L. monocytogenes attachment and persistence on soiled materials and different types of equipment surfaces, and transfer to melons in a simulated-packing environment. Attachment involved the exposure of roller conveyors (polyvinyl chloride), conveyor belts (polyvinyl chloride, polyurethane, and nitrile rubber), and brush filaments (nylon and polyethylene) to ca. 7 log10 CFU/mL of a L. monocytogenes multi-strain inoculum for 10 and 60 min. L. monocytogenes showed similar (p > 0.05) attachment to all types of surfaces, and populations attached to surfaces following exposure for 10 min were not significantly different (p > 0.05) from that attached to surfaces after 60 min. Clean and soiled surfaces of nylon-brush filaments, conveyor belts, and foam pads were each inoculated with a L. monocytogenes multi-strain mixture (4.5 log10 CFU/mL) and subsequently stored at 25 °C, and L. monocytogenes populations on the surfaces were recovered for up to 15 days. L. monocytogenes populations on clean surfaces decreased from 4.5 log10 CFU/surface on day 0 to the detection limit by day 14; L. monocytogenes was still present on clean surfaces following enrichment on day 21. However, L. monocytogenes populations remained unchanged on soiled surfaces from day 0–14. Multivariate ANOVA revealed that soiled surfaces significantly (p < 0.05) promoted L. monocytogenes persistence compared to clean surfaces. Comparison of clean surfaces revealed that foam pads and brushes significantly (p < 0.05) promoted L. monocytogenes persistence compared to conveyor belt materials. Conveyor belts and foam pads were spot-inoculated (2.5 log10 CFU/surface), and 15 consecutive wet melons were manually rolled over each spot (n = 6 replicates), and melons were tested for the presence/absence of L. monocytogenes. Foam pads were found to contaminate significantly (p < 0.05) more melons than conveyor belts (polyvinyl chloride, polyurethane, and nitrile rubber). Soiled surfaces supported the survival of higher populations of L. monocytogenes, and surface type affected L. monocytogenes contamination transferred to specific melons.

Comparison of the Memory Foam Pad Versus the Bean Bag with Shoulder Braces in Preventing Patient Displacement during Gynecologic Laparoscopic Surgery

Study ObjectiveTo compare the amount of patient displacement when a memory foam pad is used versus a bean bag with shoulder braces. The secondary aim was to evaluate for postoperative extremity symptoms including pain, numbness, and weakness. DesignA prospective randomized pilot study (Canadian Task Force classification I). SettingA single academic institution. PatientsWomen ≥18 years of age undergoing laparoscopic or robotic gynecologic surgery. InterventionsPatients were randomized to be positioned on the memory foam pad (group A) or the bean bag with shoulder braces (group B) preoperatively. The patients' positions were measured before and after the procedure, and the displacement was recorded. Patients were followed postoperatively and questioned regarding upper extremity or lower extremity weakness, numbness, and pain. Demographic characteristics were collected using the electronic medical record. Measurements and Main ResultsForty-three patients were included in the study (22 in group A and 21 in group B). The demographic and intraoperative characteristics of the patients were similar in both groups. The patients in group A moved a mean distance of 3.80 ± 3.32 cm, whereas those in group B moved a mean distance of 1.07 ± 1.93 cm (p = .002). A Pearson correlation coefficient did not yield a correlation between patient displacement and age, body mass index, length of surgery, or pathology weight. In group A, 2 patients had lower extremity numbness, and 1 patient had upper extremity numbness. In group B, 1 patient had upper extremity pain, and 1 patient had both upper and lower extremity numbness. These patients had complete resolution of their symptoms within the first 2 weeks postoperatively, with the exception of 1 patient in group A whose lower extremity numbness resolved 3 months postoperatively. ConclusionPositioning patients on the bean bag with shoulder braces resulted in significantly less displacement during gynecologic laparoscopic surgery when compared with the memory foam pad. All postoperative extremity numbness, weakness, and pain were temporary and resolved completely in our cohort. A larger study would be necessary to determine the true incidence of peripheral nerve injuries because these are rare complications of laparoscopic surgeries.

Normative Values of the Sport Concussion Assessment Tool 3 (SCAT3) in High School Athletes.

Establish sex, age, and concussion history-specific normative baseline sport concussion assessment tool 3 (SCAT3) values in adolescent athletes. Prospective cohort. Seven Wisconsin high schools. Seven hundred fifty-eight high school athletes participating in 19 sports. Sex, age, and concussion history. Sport Concussion Assessment Tool 3 (SCAT3): total number of symptoms; symptom severity; total Standardized Assessment of Concussion (SAC); and each SAC component (orientation, immediate memory, concentration, delayed recall); Balance Error Scoring System (BESS) total errors (BESS, floor and foam pad). Males reported a higher total number of symptoms [median (interquartile range): 0 (0-2) vs 0 (0-1), P = 0.001] and severity of symptoms [0 (0-3) vs 0 (0-2), P = 0.001] and a lower mean (SD) total SAC [26.0 (2.3) vs 26.4 (2.0), P = 0.026], and orientation [5 (4-5) vs 5 (5-5), P = 0.021]. There was no difference in baseline scores between sex for immediate memory, concentration, delayed recall or BESS total errors. No differences were found for any test domain based on age. Previously, concussed athletes reported a higher total number of symptoms [1 (0-4) vs 0 (0-2), P = 0.001] and symptom severity [2 (0-5) vs 0 (0-2), P = 0.001]. BESS total scores did not differ by concussion history. This study represents the first published normative baseline SCAT3 values in high school athletes. Results varied by sex and history of previous concussion but not by age. The normative baseline values generated from this study will help clinicians better evaluate and interpret SCAT3 results of concussed adolescent athletes.

An experimental study on shock wave mitigation capability of polyurea and shear thickening fluid based suspension pads

Abstract The present experimental study investigates shock wave mitigation capability of potentially new personal protective equipment (PPE) suspension pads made from polyurea and shear thickening fluid (STF). The shock tube test results show that when placed behind Twaron fabric systems with thickness ranging from 2 mm to 18 mm, the replacement of conventional flexible foam pad with STF and STF-infused foam pads with the same thickness of 20 mm greatly reduces the normalized peak pressure (by about 72% for each pad). However, this benefit is partially offset by a large increase in the normalized impulse (by about 78% for the STF pad and 131% for the STF-infused foam pad) which may cause the shock wave mitigation performance of these two pads to become less effective. Interestingly, the use of 4 mm thick polyurea pad can greatly reduce the normalized peak pressure and impulse as well (by about 74% and 49%, respectively). These results reveal that among the potentially new suspension pads tested, the polyurea pad displays the best shock wave mitigation performance. Therefore, polyurea has potential for use as a suspension pad in personal protective equipment requiring shock wave mitigation capability such as fabric ballistic vests, bomb suits and combat helmets.

Effect of hearing aids on static balance function in elderly with hearing loss

While a few studies have investigated the relationship between hearing acuity and postural control, little is known about the effect of hearing aids on postural stability in elderly with hearing loss. The aim was to compare static balance function between elderly with hearing loss who used hearing aids and those who did not use. The subjects asked to stand with (A) open eyes on rigid surface (force platform), (B) closed eyes on rigid surface, (C) open eyes on a foam pad, and (D) closed eyes on a foam pad. Subjects in the aided group (n=22) were tested with their hearing aids turned on and hearing aids turned off in each experimental condition. Subjects in the unaided group (n=25) were tested under the same experimental conditions as the aided group. Indicators for postural stability were center of pressure (COP) parameters including; mean velocity, standard deviation (SD) velocity in anteroposterior (AP) and mediolateral (ML) directions, and sway area (95% confidence ellipse). The results showed that within open eyes–foam surface condition, there was greater SD velocity in the off-aided than the on-aided and the unaided than the on-aided (p<0.0001 for SD velocity in AP and ML). Also, no significant differences were found between the off-aided and unaided group (p=0.56 and p=0.77 for SD velocity in AP and ML, respectively). Hearing aids improve static balance function by reducing the SD velocity. Clinical implications may include improving hearing inputs in order to increase postural stability in older adults with hearing loss.

Adaptation effects in static postural control by providing simultaneous visual feedback of center of pressure and center of gravity

BackgroundThe benefit of visual feedback of the center of pressure (COP) on quiet standing is still debatable. This study aimed to investigate the adaptation effects of visual feedback training using both the COP and center of gravity (COG) during quiet standing.MethodsThirty-four healthy young adults were divided into three groups randomly (COP + COG, COP, and control groups). A force plate was used to calculate the coordinates of the COP in the anteroposterior (COPAP) and mediolateral (COPML) directions. A motion analysis system was used to calculate the coordinates of the center of mass (COM) in both directions (COMAP and COMML). The coordinates of the COG in the AP direction (COGAP) were obtained from the force plate signals. Augmented visual feedback was presented on a screen in the form of fluctuation circles in the vertical direction that moved upward as the COPAP and/or COGAP moved forward and vice versa. The COP + COG group received the real-time COPAP and COGAP feedback simultaneously, whereas the COP group received the real-time COPAP feedback only. The control group received no visual feedback. In the training session, the COP + COG group was required to maintain an even distance between the COPAP and COGAP and reduce the COGAP fluctuation, whereas the COP group was required to reduce the COPAP fluctuation while standing on a foam pad. In test sessions, participants were instructed to keep their standing posture as quiet as possible on the foam pad before (pre-session) and after (post-session) the training sessions.ResultsIn the post-session, the velocity and root mean square of COMAP in the COP + COG group were lower than those in the control group. In addition, the absolute value of the sum of the COP − COM distances in the COP + COG group was lower than that in the COP group. Furthermore, positive correlations were found between the COMAP velocity and COP − COM parameters.ConclusionsThe results suggest that the novel visual feedback training that incorporates the COPAP–COGAP interaction reduces postural sway better than the training using the COPAP alone during quiet standing. That is, even COPAP fluctuation around the COGAP would be effective in reducing the COMAP velocity.

Numerical evaluation of time-dependent sagging for low density polyurethane foams to apply the long-term driving comfort on the seat cushion design

Car seat's bearing capacity, after a person takes a seat, is time dependent and tend to harden with increased time. Hardening of seat results from viscoelasticity of seat's foam pad, and has a great effect on a person's seating comfort in a long term driving mode. As such, evaluation of changes to bearing capacity is an important design factor that must be considered at the time of the seat design, and need to be evaluated quantitatively. This study intends to apply numerical analysis for quantitative evaluation of the changes to bearing capacity of seat cushions during a long term driving, and evaluate based on different materials of seat foam pads to be used as a reference material during the design. Car seat's comfort functions are divided into static comfort, evaluated in a time domain, and dynamic comfort, evaluated in a vibrating domain. However, as this study only intends to evaluate the seat cushion's hardening effects during a long term driving, we only evaluated the static comfort in a time domain. We assumed the long term driving to be two hours, quantified the hardening level to an amount of sagging, and evaluated three types of low density polyurethane foams with different material characteristics. We applied the analysis method used and verified in the previous research phase to numerically evaluate the amount of sagging depending on the seating time, and tested the foam pad's static compressive behavior and viscoelasticity behavior to acquire data on material's characteristic. In order to consider body's seating position, we used HPM-1 dummy model provided by ESI's PAM-COMFORT (finite-element analysis program exclusively for seat), and compared the amount of sagging. We were able to predict the amount of sagging of each material from the analysis results and confirmed noticeable differences.