Evacuation safety effects of a lightweight elevator-type evacuation device using carbon material: Focus on plantar pressure and muscle strength.

BACKGROUND: Elevator-type evacuation devices have proven to be feasible in high-rise buildings through studies on safety performance and evacuation time. However, there is a lack of research on safety using biosignal analysis in the elderly population. OBJECTIVE: A carbon material is used in this study to reduce the weight of an evacuation elevator. The impact on the human body is evaluated by conducting a satisfaction survey involving elderly and youth groups and quantitatively analyzing biological signals, including electromyography (EMG) and plantar pressure, during five repeated uses of the proposed device. METHODS: The study involves 12 healthy adults in their 20s and 20 elderly individuals with no experience in using an evacuation elevator. The EMG and left and right plantar pressures are analyzed to evaluate the physical factors affected by repeated use. RESULTS: The experiment results showed that the normalization of EMG to maximum voluntary contraction showed a significant decrease with repeated use, especially in the right tibialis anterior muscle. Moreover, plantar pressure shows a significant difference, which decreased with repetition, and the left and right balance gradually tilted to the left. CONCLUSION: This suggests that with more repeated use, muscle tension decreases owing to adaptation, resulting in lower muscle activity and plantar pressure. Particularly, the tibialis anterior muscle experiences significant muscle activity, indicating increased load, but without any apparent danger. In the future, it will be necessary to evaluate elevators for disabled individuals.

The development of split-treadmill with a fall prevention training function.

BACKGROUND: The weakening of the ability of the elderly to perform gait is becoming a major cause of the increase in the frequency of falls. OBJECTIVE: In this study, we designed and manufactured a treadmill capable of restraining walking by providing a sudden repulsive force on the left and right legs of a pedestrian when walking for the fall prevention training of the elderly. Through this, it is possible for the elderly person to strengthen the lower extremity muscles to prevent and prepare for falling through the fall prevention training similar to the fall environment that may occur in daily life. METHOD: The development system includes a motor for generating a driving force in the form of a left and a right driving system and a belt separated from each other, an electromagnetic clutch for rapidly stopping the running belt of the motor transmitted to the running belt to stop the running belt, and a controller for controlling the driver. RESULTS: In order to evaluate the development system, the motor driving ability test and the power transmission, connection and shut-off performance of the electromagnetic clutch were carried out. The subject's muscle activity of the lower extremity muscles was evaluated when the running belt stopped at the beginning of the right folding. CONCLUSION: It is expected that the developed dual function system would be helpful for the fall prevention exercise as well as the rehabilitation exercise for patients who have recovered from surgery or hemiplegic patients.

Characteristics of physiological data during asymmetric gait of healthy subjects using a two-belt treadmill.

BACKGROUND: Mobile rehabilitation systems for patients with gait disorder are being developed. Safety functions to prevent patients from falling are considered during product development; however, few studies have been conducted on systems that have been prevalidated for healthy adults prior to application to patients. OBJECTIVE: This study analyzed the characteristics of lower extremity muscles and foot pressure in healthy adults during unbalanced walking with differences in the speed of left and right speed using a two-belt treadmill. METHODS: Twenty subjects performed gait motions with a difference in the weight support conditions (0% and 30%) and the left and right lower limb speeds (1-3 km/h). Each subject's muscular activities and foot pressure signals were collected. The gait patterns of the faster side exhibit similar characteristics to the paralyzed leg, and the slower side is similar to the non-paralyzed leg. RESULTS: Weight-supporting healthy subjects showed asymmetric gait patterns, similar to hemiplegic patients, because of the difference in the speed of the left and right side. CONCLUSIONS: The quantitative results can be used to develop a training protocol for two-belt treadmills with differently controlled left and right speeds for gait rehabilitation in hemiplegic patients.

The effect of exercise load deviations in whole body vibration on improving muscle strength imbalance in the lower limb.

BACKGROUND: The amount of patients with muscle imbalance of the left and right side increases rapidly due to an incorrect lifestyle. OBJECTIVE: We investigated the optimal exercise load required to improve muscle imbalance. METHODS: Thirty participants were enrolled in the study. They performed squat exercises according to a whole body vibration (WBV) frequency protocol over a period of eight weeks. The exercises were performed three days a week and comprised five sets of fifteen trials per set per day. We validated muscle imbalance improvement using WBV by comparing and analyzing the results at different vibration frequencies. The participants were divided into three WBV protocol groups: no WBV, low-frequency WBV (25 Hz and 5 mm amplitude), and high-frequency WBV (50 Hz and 5 mm amplitude). We estimated the isokinetic muscle functions of the hip, knee, and ankle joints using BIODEX system 3. Ultimately, low-frequency WBV improved balance 10.2 ∼ 26.5% more than high-frequency WBV. RESULTS: Continuous load-deviation motions during low-frequency WBV were more effective at improving muscle imbalance than high-frequency WBV. WBV load variation methods improved muscle function and contractility more than external weights or loads by directly transferring kinetic energy into the body. CONCLUSION: In this clinical study, we demonstrated that low-frequency WBV was more effective at improving muscle imbalance. The WBV protocol can be used in rehabilitation programs to improve imbalance without requiring elderly or physically decompensated patients to participate in excessive exercise.

A study on trunk muscle activation patterns according to tilt angle during whole body tilts.

BACKGROUND: Lower back pain has a lifetime prevalence of 80% for people in a modern society, and in recent years, spinal stabilization movement has been highlighted as a method to treat lower back pain and an unbalanced position. OBJECTIVE: The objectives of this study were to assess the trunk muscle activities in accordance with the tilt angles (10∘, 20∘, 30∘, 40∘) during trunk tilt exercises with a 3D dynamic exercise device. METHODS: Active tilt mode (a self-generated active movement in the angle and direction steered by the user) was used in this study. The rotation capability enabled the investigation of the anterior (A), anterior right (AR), right (R), posterior right (PR), posterior (P), posterior left (PL), left (L), and anterior left (AL) tilt directions. EMG signals of the trunk (3 global muscles: rectus abdominis, RA, external obliques, EO, latissimus dorsi, LD, and 1 local muscle: multifidus, MF) muscles were obtained. RESULTS: The MF muscle activity was higher while the anterior tilt was maintained, and the abdominal muscle activity was higher while the posterior tilt was maintained. Also, as the tilt angle increased, the activity of the muscles opposite the tilt direction increased. CONCLUSIONS: The results indicate that to maintain equilibrium through posture stabilization during whole body tilting, the human body maintains a proper interaction among the body segments as well as between the body and the execution environment. Moreover, stability is maintained through the co-contraction of antagonistic and agonistic muscles. In future studies, it will be important to conduct research on improving imbalance in the trunk muscles.

Effect of whole body vibration on lactate level recovery and heart rate recovery in rest after intense exercise.

OBJECTIVE: In this paper, we investigated the recovery of the lactate level, muscular fatigue, and heart rate recovery (HRR) with respect to whole body vibration (WBV) during the rest stage after a gait exercise. METHODS: A total of 24 healthy subjects with no medical history of exercise injury participated. The participants were divided into a training group with vibration during rest and a control group with the same conditions but without vibration. The subjects performed a gait exercise with a slope of 15% and velocity of 4 km/h to consume 450 kcal in 30 min. Then, they rested on a vibrating chair or on a chair without vibrations for 30 min. The vibration protocol consists of a frequency of 10 Hz and amplitude of 5 mm. To estimate the recovery effect, we measured the lactate levels in blood, spectral edge frequency (SEF) of MVIC, and HRR before, immediately after exercise, and after rest. RESULTS: The results showed that the lactate level in the training group decreased more (93.8%) than in the control group (32.8%). Also, HRR showed a similar trend with a recovery of 88.39% in the training group but 64.72% in the control group. We considered that whole-body vibrations during rest would help remove lactic acid by improving the level of lactic acid oxidation with stimulated blood vessels in the muscles and by helping to maintain blood flow. Also, WBV would lead to compensation to actively decrease the fast excess post-exercise oxygen consumption from blood circulation. CONCLUSIONS: We suggest that whole-body vibrations during rest can provide fast, efficient fatigue recovery as a cool down exercise for women, the elderly, and patients without other activity after intense exercise.

Preliminary study on verifying the detection of gait intention based on knee joint anterior displacement of gait slopes.

This study investigated the feasibility of the Infrared (IR) sensor-based walking aids for detecting the gait intention. To compensate for the defects of Force Sensing Resistors (FSRs) or force sensors, such as the velocity control problem on gait slopes, we used IR sensors to investigate knee joint anterior displacement in order to recognize the gait intention. We also measure leg muscle activities and foot pressure, in order to verify our investigation. We placed two IR sensors on the rollator center to sense left and right leg walking intentions. We took EMG signals of four leg muscles, and analyzed them. Foot pressure analysis parameters were the measured force and mean pressure. We conducted experiments on twenty young healthy adults. The results show that knee joint anterior displacement increases according to gait slope and velocity. We confirm similar results of knee joint anterior displacement through the IR sensors.

Effect of vibration on muscle strength imbalance in lower extremity using multi-control whole body vibration platform.

This study shows the improvement of muscle activity and muscle strength imbalance in the lower extremities through independent exercise loads in vibration platform. Twenty females of age 20 participated in this study. The subjects were divided into WBV group, with more than 10% of muscle strength imbalance between left and right the lower extremities, and control group, with less than 10% of muscle strength imbalance between left and right the lower extremities. As the prior experiment showed, different exercise postures provide different muscular activities. As a result, the highest muscular activity was found to be in the low squat posture. Therefore, the LS posture was selected for the exercise in this experiment. Vibration intensities were applied to dominant muscle and non-dominant muscle, and the vibration frequency was fixed at 25Hz for the WBV group. The control group was asked to perform the same exercise as the WBV group, without stimulated vibration. This exercise was conducted for a total of 4 weeks. As a result, the WBV group which showed an average deviation of 16% before the experiment, tended to decrease approximately to 5%. In this study, vibration exercise using load deviation is shown to be effective in improving the muscle strength imbalance.

Comparative analysis for evaluating the traceability of interventional devices using blood vessel phantom models made of PVA-H or silicone.

OBJECTIVE: In this paper, we investigated the parameters with effective traceability to assess the mechanical properties of interventional devices. METHODS: In our evaluation system, a box-shaped poly (vinyl alcohol) hydrogel (PVA-H) and silicone were prepared with realistic geometry, and the measurement and evaluation of traceability were carried out on devices using load hand force. The phantom models had a total of five curve pathways to reach the aneurysm sac. RESULTS: Traceability depends on the performance of the interventional devices in order to pass through the curved part of the model simulation track. The traceability of the guide wire was found to be much better than that of the balloon and stent loading catheter, as it reached the aneurysm sac in both phantom models. CONCLUSIONS: Observation using the video record is another advantage of our system, because the high transparency of the materials with silicone and PVA-H can allow visualization of the inside of an artery.

Feasibility of compressive follower load on spine in a simplified dynamic state: a simulation study.

This study investigated that the spinal MFs can create compressive follower loads (CFLs) in the lumbar spine in a dynamic state. Three-dimensional optimization and finite element (FE) models of the spinal system were developed and validated using reported experimental data. An optimization analysis was performed to determine the MFs that create CFLs in the lumbar spine in various sagittal postures from 10° extension to 40° flexion. Optimization solutions for the MFs, CFLs, and follower load path (FLP) location were feasible for all studied postures. The FE predictions demonstrated that MFs which created CFLs along the base spinal curve connecting the geometrical centers or along a curve in its vicinity (within anterior or posterior shift by 2 mm) produced stable deformation of the lumbar spine in the neutral standing and flexed postures, whereas the MFs which created the smallest CFLs resulted in unstable deformation. For extended postures, however, finding CFLs creating MFs that produce stable deformation of the extended spine was not possible. The results of this study support the hypothesis that the spinal muscles may stabilize the spine via the CFL mechanism.

Analysis of basal physical fitness and lumbar muscle function according to indoor horse riding exercise.

The aim of this study is to verify the effect of indoor horse riding exercise on basal physical exercise and lumbar muscular function. The subjects included were 20 healthy females, who participated in the horse riding exercise using SRider (Rider Co. & ChonbuK National Univ, Korea) for 30 minutes per day, 3 days per week, over a period of 8 weeks. The subjects were divided into 4 groups as follows, with 10 subjects in each group: Postural Balance Exercise mode (PBE), Abdomen Exercise mode (ADE), Whole body Exercise mode (WBE), and Multiple Exercise (MTE). Isokinetic muscular function test was performed before and after the horse riding exercise, to assess the effect of horse riding on basal physical exercise and lumbar muscular function. The test result on basal physical exercise and isokinetic muscular function showed improvements with variable degree in the back muscle strength, maximum joint torque, total work, and muscular acceleration time. The result signifies that the horse riding is an antagonistic exercise mainly performed on waist and abdomen area, and the machine induces persistent muscle contraction and causes myotonic induction enhancing the muscle strength. Indoor horse riding exercise proved its effectiveness for senior or the disabled people who need muscle exercises but have difficulties performing outdoor activities.

Fundamental study of basal physical fitness and activities of daily living for the aged in relation to indoor horse riding exercise.

In this study, we assessed indoor horse riding exercise's effects on basal physical exercise and activities of daily living (ADL) function using horse riding equipment, involving elderly test subjects (in their sixties). The participants were 20 people with no impediment to activity. They participated in experiments that lasted 60 min per day, 3 days per week, over 8 weeks, using the "SRider" (Rider Co. and Chonbuk National University Korea).We measured trunk flexion, sit-up, whole-body reaction, leg strength, and maximal oxygen uptake as basal physical fitness parameters. Also, 3-m gait, single stance with eyes open, and single stance with eyes closed, as ADL functions, were estimated once per month. The leg strength and whole body reaction result were significantly higher than before the exercise program. Moreover, the results of the 3-m walking ability alone increased significantly among the ADL functions. These findings indicate that the horse riding exercise may activate continuous muscular contraction, maintaining the tonus of the muscles. The continuous movement of horse riding could be lead to isometric muscle contraction in the lower limbs. These results suggest that the horse riding exercise develops muscle power and muscle reactions with exercise.

Comparative analysis of basal physical fitness and muscle function in relation to muscle balance pattern using rowing machines.

The purpose of this study was to evaluate muscle function and basal physical fitness in relation to muscle balance pattern using rowing machines. Twenty four subjects participated in this study, using three different rowing machines. Rowing exercises were performed for twenty-five times a set, four sets a day, 3 days a week, for 8 weeks. Biodex system 3(Biodex Medical Systems Co., New York, USA) was used to measure joint torques in the elbow, shoulder, lumbar and knee of subjects, for analyzing muscle function. The evaluation of basal physical fitness included body composition, muscle strength, muscle endurance, muscle reaction, agility, flexibility and explosive power. Before the experiment, significant differences of joint torques in the elbow, shoulder, lumbar and knee were present between subjects in the group. After the rowing exercise, significant improvement in every joint was witnessed. All aspects of basic fitness increased significantly, and the most improvement was observed in muscle strength from the joint torque results. As shown in the following results, every joint it was evident to have improved by more than 30% with the use of dependent load deviation type over the previously used water load method. This means that it is more effective for enhancing muscle strength and endurance to keep the muscle balance using dependent load deviation. The human body maintains motor coordination of muscle contraction during exercise. The muscle balances in the upper-lower and left-right arms could assist with effective activation of motor coordination. In this paper, an exercise method using dependent load deviation was demonstrated to be more efficient for improving muscle imbalance and strengthening muscles.

Study of parameters for evaluating flow reduction with stents in a sidewall aneurysm phantom model.

The effect of stent design parameters such as porosity, pore density, number of strands, and strut angle to the artery were studied in vitro using particle image velocimetry (PIV). Five mesh stents were implanted into a sidewall aneurysm model. The flow features in a sidewall aneurysm silicone phantom model were investigated at a Reynolds number of 300. It was found that the lowest porosity stent had the best value for velocity and vorticity reduction in an aneurysm pocket. The stent with higher pore density had a tendency to decrease the mean and maximum velocities, but it was not superior to the effects of porosity. In addition, investigation of the evaluation system confirmed that higher stent strut angles to the parent artery had a tendency to lower mean velocity, as shown by PIV and CFD. However, this effect was relatively smaller compared to porosity and pore density. Our evaluation system suggested the best combinations of parameters for the development of an ideal stent would be lower porosity, higher pore density, and higher strut angle. The results obtained in this study indicated that our evaluation system could be useful for various purposes related to evaluation of endovascular interventional devices.

Fundamental study of lower limb muscle activity using an angled whole body vibration exercise instrument.

This research was performed to assess the effects of angled whole body vibration on muscle activity of the lower limbs, by examining adults in their twenties during squat exercises, taking into account two variables of exercise intensity (vibration frequency and gradient). Twenty healthy males in their twenties with previous experience of more than 6 month's weight training and no past medical history were included in this study. The experiment was performed by participating in squat exercises which consisted of 3 sets (1 set = 5 seconds x 3 repetitions of exercise), and the muscle activities of the Rectus Femoris, Vastus Lateralis, Vastus Medialis were measured with variation in the gradients of 0°, 10°, and 20°, and vibration frequencies of 20, 30, and 40 Hz. At 30 and 40 Hz, the vastus lateralis showed the highest change in muscle activity, while activity of the vastus medialis also increased significantly. Analysis of muscle activity according to the gradient showed a significant increase of the vastus lateralis at 20°, while the highest muscle activity at 20° was observed for the vastus medialis. In comparison of the change in lower limb muscle activity according to simultaneous stimulation, at a gradient of 10°, high activity was shown in muscle, while at 20°, high muscle activities were produced at 40 Hz in the vastus lateralis, 40 Hz in the rectus femoris, and both 30 and 40 Hz in the vastus medialis.

Effect of recovery from muscle strength imbalance in lower limb using four point weight bearing reduction system.

This study was performed to assess the improvement of muscle strength imbalance in the lower limbs using a four point weight bearing reduction system with a two-belt treadmill. Participants, each having differences in muscle function of the left and right legs of over 20%, were divided into two groups of ten. The participants were involved in experiments progressing 40 minutes per day, 3 days per week, during a period of 4 weeks. The maximal peak torque and average power were measured for testing joint torque in the hip, knee and ankle. The results showed the improvement of muscle imbalance as assessed by the maximal muscle strength was the most effective in the hip joint, while the improvement of muscular reaction was the most effective in the knee joint. We suggest that the method of weight bearing reduction could be sufficient to reduce muscle imbalance in the lower limbs.

Postural responses during the various frequencies of anteroposterior perturbation.

This study investigated the characteristics of dynamic postural responses when subjects attempted to maintain an upright standing position on a support plate during continuous sinusoidal perturbation in the anterior-posterior direction. Fifteen healthy young subjects participated in the experiment. Body movement patterns during the perturbation were captured and analyzed using a 3D motion analysis system (APAS 3D motion analysis, Ariel Dynamics Inc.). Seven markers were attached on the subject's body to measure and analyze the motion patterns. The markers were positioned at the head, chest, hip, right knee, left knee, right ankle, and left ankle. Five different frequencies of motion were applied to the support surface: 0.1, 0.5, 1.0, 1.5, and 2.0 Hz with a 4-cm path of motion at the base. The experiments measured dynamic postural responses in a condition were subjects had their eyes open. The results showed that the median frequency of the knee and ankle increased in all frequency bands. Following an increase in the frequency of the perturbation, the postural control strategy was changed from the ankle strategy to a combined strategy. These experimental results could be applied to the dynamic postural training for the elderly and to rehabilitation training for patients to improve their ability for postural control.

Influence of bundle diameter and attachment point on kinematic behavior in double bundle anterior cruciate ligament reconstruction using computational model.

A protocol to choose the graft diameter attachment point of each bundle has not yet been determined since they are usually dependent on a surgeon's preference. Therefore, the influence of bundle diameters and attachment points on the kinematics of the knee joint needs to be quantitatively analyzed. A three-dimensional knee model was reconstructed with computed tomography images of a 26-year-old man. Based on the model, models of double bundle anterior cruciate ligament (ACL) reconstruction were developed. The anterior tibial translations for the anterior drawer test and the internal tibial rotation for the pivot shift test were investigated according to variation of bundle diameters and attachment points. For the model in this study, the knee kinematics after the double bundle ACL reconstruction were dependent on the attachment point and not much influenced by the bundle diameter although larger sized anterior-medial bundles provided increased stability in the knee joint. Therefore, in the clinical setting, the bundle attachment point needs to be considered prior to the bundle diameter, and the current selection method of graft diameters for both bundles appears justified.

Activity analysis of trunk and leg muscles during whole body tilt exercise.

The objectives were to assess the trunk and leg muscle activities during the trunk tilt exercise by a 3D dynamic exercise device capable of active and passive movements, to study the evaluation of Root Mean Squire (RMS), and to investigation the influence of the trunk positions on these muscle activities. Eighteen healthy volunteers were selected. None of the subjects had any history of lumber and trunk muscle problems. Rotation capability was enabled for the investigation of A (anterior), R (right), P (posterior), L (left), AR (anterior right), AL (anterior left), PR (posterior right), PL (posterior left) tilt directions. EMG signals of trunk (rectus abdominis, external obliques, latissimus dorsi, erector spinae) muscles and leg (rectus femoris, Biceps femoris, Tibialis Anterior, gastrocnemius) muscles were taken out. Root Mean Squire (RMS) values were calculated. The results of this study indicate that different exercise patterns can be applied depending on the exercise types, which are appropriate and necessary to each user. We believe that the human body can be maintained in equilibrium through the interaction between the position and movement execution of the human body, contributing to the improvement of body balance control. Further quantitative data collection and analysis related to the development of various spinal stabilization exercise programs is required. In the near future, we will conduct a study concerning the effects of trunk tilt exercise in active and passive modes on the strength of the tilting muscles and postural balancing ability.

Characteristic analysis of the lower limb muscular strength training system applied with MR dampers.

A new training system that can adjust training intensity and indicate the center pressure of a subject was proposed by applying controlled electric current to the Magneto-Rheological damper. The experimental studying on the muscular activities were performed in lower extremities during maintaining and moving exercises, which were processed on an unstable platform with Magneto rheological dampers and recorded in a monitor. The electromyography (EMG) signals of the eight muscles in lower extremities were recorded and analyzed in certain time and frequency domain. Muscles researched in this paper were rectus femoris (RF), biceps femoris (BF), tensor fasciae latae (TFL), vastuslateralis (VL), vastusmedialis (VM), gastrocnemius (Ga), tibialis anterior (TA), and soleus (So). Differences of muscular activities during four moving exercises were studied in our experimental results. The rate of the increment of the muscular activities was affected by the condition of the unstable platform with MR dampers, which suggested the difference of moving exercises could selectively train each muscle with varying intensities. Furthermore, these findings also proposed that this training system can improve the ability of postural balance.