In human skeletal muscles in vivo, there is a lengthwise interaction between muscle fibers and tendinous tissues due to slackness and elastic property of tendinous tissues (muscle-tendon interaction). This study aimed to investigate the effects of the muscle-tendon interaction on 1) time to force onset and 2) time-course of force during force development, through measurements of fascicle behavior using the Motion-mode and Brightness-mode ultrasolography. The muscle-tendon interaction affected over-40% of the time from stimulus to force production, and the following time-course alteration of force generating capacities as a function of slackness and operating range in non-linear length-force relationship of tendinous tissues. These would influence joint angle-dependence of electro mechanical delay and time-course change of fascicle force.

Mechanomyogram (MMG) which measures the slight vibration of muscle contraction can evaluate the mechanical function of the muscle. There are few reports describing the surface displacement (displacement-MMGs) along the cross-section direction during tetanus. Using the laser displacement sensor, we recorded the displacement-MMGs of the human Rectus Femoris (type Ⅱ superiority) and Abductor Pollicis Brevis (type I superiority) during tetanus with a 30-s continuous electrostimulation at the frequency ranging from 0.2 to 50 [Hz], and discussed the contraction properties of these mixed fiber-type skeletal muscles. Three male and one female subjects (21- to 25-year-old) without medical histories of muscular disease joined the experiment repeatedly. The results showed that incomplete tetanus in the mixed fiber-type skeletal muscles were induced by two steps, and the displacement-MMG amplitude was affected by the component ratio of the area of muscle fiber. Furthermore, according to contraction and relaxation time of muscle force in type I, II twitches, the frequency regions of the first phase of incomplete tetanus and the second almost corresponded with those of type I and type II, respectively.

The stimulus-response (S-R) compatibility effect refers to differences in performance due to the spatial S-R relationship. We investigated whether S-R compatibility has an effect on motor programming. Reaction time was divided into premotor and motor times using electromyography. The temporal feature of the neural activities of the primary motor cortices was estimated by magnetoencephalography. Premotor and motor times in the incompatible task were longer than those in the compatible task. The neural activity of the motor cortex for the incompatible response was weaker than that for the compatible response. These results suggest that the S-R compatibility influences not only the time of information processing but also motor programming. We elucidate the neural mechanisms of dual-route processing related to automatic and controlled activations.

In this study, we aimed to investigate whether or not the difference in the motor output adjustment function based on the somatosensory inputs (somatosensory-motor integrated function) depends on the motor experiences. In order to compare the difference in the somatosensory-motor integrated function, subjects were classified into an athlete group and a general group based on their motor experiences. The somatosensory-motor integrated function was examined using a kinetic-equilibrating task, position reproduction task and force reproduction task. In the kinetic-equilibrating task, passive force was applied to the subjects by using a original experimental apparatus, and they were instructed to maintain stable limb position. In the force and position reproduction task, the subjects were instructed to reproduce the knee extension force or knee joint angle based on a reference state previously memorized by the subject. Based on the results of the kinetic-equilibrating task, the athlete group showed greater respons on the somatosensory-motor integrated function as compared to the general group. In addition, the somatosensory-motor integrated function was related to the threshold to detect the passive movement, which indicates the somatosensory function, and related to the force fluctuation, which indicates the motor function. In conclusion, it was suggested that the athletes were greater on the somatosensory-motor integrated function, which includes both somatosensory and motor functions.

Our purpose was to examine the kinematic and electrophysiological changes during elbow flexion and extension by tracking task acquisition with varying target acceleration. Task acquisition was assessed from the degree of movement error and movement acceleration profiles estimated using the surface electromyographic (EMG) activity and the muscle cocontraction index (CI). Subjects were divided into well-performing and poorly performing groups to compare task acquisition between the 2 groups. The results showed that the movement error decreased with an increase in the number of trials. Moreover, the EMG activity changes differed between the 2 groups. The movement acceleration profiles also appeared similar to the target wave (single peak acceleration). The correlation coefficient between target and movement acceleration increased with the progress of acquisition, indicating acquisition of movement smoothness. EMG activities were regulated by task acquisition, and the pattern of EMG changes depended on the performance level. The CI was lower in the well-performing group than in the poorly performing group, showing difference in muscle activity regulation between the 2 groups. In conclusion, movement error, muscle activity (including CI), and correlation coefficient between target and movement acceleration can be used to evaluate movement smoothness and muscle activity regulation by tracking task acquisition with varying target acceleration.

The purpose of this investigation was to examine the effect of a 6-8 week training program with three speed pattern squats on various physical performance. Twelve male and six male athletes with varying levels of resistance training experience performed sessions of squats with either Strength type (5RM*5set, 6 male) or Slow type (8-15RM*6set, 6 male) or Speed type (15reps*5set, 8 athletes). Anatomical cross sectional area (ACSA) of Quadriceps, Hamstrings, Adductor muscles, and Gluteus maximus, and some body composition were measured, and a 30 m sprint, Counter movement jump, Rebound drop jump, Muscle power at Cybex were performed before and after training. There were significant increases in ACSA of Quadriceps and Hamstrings for the Slow type training group only. In contrast, the Strength and Speed type training groups significantly increased 30 m sprint and Drop jump performance. And the Strength type training groups also significantly increased in the hip extensor muscles power. This investigation indicates that resistance training with slow movement results cause muscle hypertrophy, but appear to have no significant effect about jumping and running performances. On the other hand, the resistance training with high volume and high speed results in increased movement velocity capabilities and that velocity specific changes were caused by effective use of stretch shortening cycle.

There have not yet been any musculoskeletal analysis of swimming, since it has been difficult to compute the fluid force acting on the whole body of a swimmer. Therefore, in order to make the musculo-skeletal analysis of swimming feasible, we developed a whole body musculoskeletal simulator for swimming. Two simulation models were integrated in this simulator. The first was the swimming human simulation model SWUM, which was developed by the authors and is capable of computing the fluid force acting on the whole body of a swimmer. The other model was the AnyBody Modeling System for musculoskeletal analysis. In this study, we first developed data transformation methods for transforming the output data from SWUM (body geometry, joint motion and fluid force) into input data for musculoskeletal analysis. Next, we constructed an integrated simulator by implementing these data transformation methods within a piece software also including SWUM. Using the simulator so developed, we conducted analyses of the four swimming strokes (crawl, breast, back, and butterfly). In addition, we examined the validity of this simulator by comparing its analytical results with the experimental results from previous electromyogram studies. The results of the comparison show good agreement between the analysis and experiments with respect to the timing of muscle activity, indicating that the simulator is sufficiently valid to estimate the timing of the muscle activity.

The purpose of this study was to investigate the relationship of the number of pitches to the kinetics changes of pitching during a simulated baseball game. Three male college baseball pitchers threw 15 pitches in an inning for 9 innings (135 pitches) in an indoor pitcher's mound with two force platforms. Rest time between innings was 6 minutes. Three-dimensional positions of 47 reflective markers attached to subject were tracked by an optical motion capture system (Vicon Motion System 612, Oxford Metrics) with eight cameras (250 Hz).For each subject 75 fastball pitches (1st, 3rd, 5th, 7th, and 9th inings) were chosen for analysis. Kinetic parameters were analyzed by simple linear regression analysis at three instants of motion events (p<0.05).

As the main results, the stride leg hip joint extension positive, negative and absolute work decreased with increasing the number of pitches. The throwing arm shoulder joint internal rotation positive work decreased with increasing the number of pitches. The throwing arm shoulder joint horizontal adduction positive and absolute work increased with increasing the number of pitches.

The purpose of this study was to investigate relationship of pain presence to kinetic deviation and asymmetry of the lower limb joints during gait for athletes suffered from various lower limb pains. The gait of 112 athletes was analyzed three-dimensionally with a Vicon 612 system. Deviation and asymmetry of the three-dimensional lower limb kinetics obtained by an inverse dynamics approach were evaluated by calculating Z score. In the lumber-pain group, the increase in the hip extension torque in the forward propulsion phase caused greater kinetic deviations. In the hip-pain group, the increase in hip flexion torque in the latter phase of the stance caused greater kinetic deviations and the decrease in the ankle plantar flexion torque of the affected limb caused greater asymmetry. In the knee-pain group, the increase in the hip abduction torque caused greater kinetic deviations and the decrease in the affected limb caused greater asymmetry. In the ankle-pain group, the increase in the ankle plantar flexion torque in push-off phase of the affected limb caused greater asymmetry. These results indicated the motion deviation and asymmetry of the lower limb kinetics can be detected by Z score during the gait in the athletes who suffered from pains in the lower limbs and that the technique was in this study may be one of effective methods used predict the risk of lower limb injuries for athletes.

The purpose of this study was to obtain quantitative information about head movements during linear walking in humans. Subjects (26-33 years old) walked on a motor-driven linear treadmill (Q55, Quinton) at walking velocities of 0.6 to 2.2 m/sec. The head and trunk were modeled as rigid bodies, and their rotation and translation were determined in space coordinates using a video-based motion analysis system (OPTOTRAK 3020, Northern Digital Inc). During walking the trunk rotated in the coronal plane to the supporting limb side. This was compensated by the head roll rotation relative to the trunk over the range of walking speed tested, indicating that the angular VCR (vestibulocollic reflex) functions to produce a compensatory head roll on trunk to maintain head stability in the coronal plane during walking. Head, however, still rotated in space within a range of a few degrees during moderate-to-fast walking. This was almost in phase with change in the GIA (gravito-inertial acceleration vector), suggesting that in the coronal plane the head rotation is orientation response to change in the GIA. A series of our recent studies has revealed that there are considerable well-coordinated head and upper trunk movements in all three planes during locomotion, and have suggested that these compensatory and orienting responses of the head must be considered when modeling human bipedal walking.

Fatigue resulting from long-term driving can be classified into physical and mental fatigue. Physical fatigue seems to be mainly caused by driving posture. The purpose of this study is to develop a new driving posture for reduction of causal factors of physical fatigue, that is, biomechanical loads caused by the posture. In this paper, driving posture was optimized by subjective adjustments of sitting posture and seat contours considering necessary conditions for driving operations and forward view. The new driving posture was validated by biomechanical analysis of musculo-skeletal loads and contact loads. The posture was also evaluated in dynamic long-term driving by qualitative and quantitative measurements. The results showed physical fatigue of the new posture was halved in comparison with the one of the conventional posture in same car by subjective evaluations. Therefore, fatigue reduction of the new posture was qualitatively validated. Physiological indices had same tendency with subjective evaluations. From the results, we extracted six physiological indices as good measures of physical fatigue during driving. The effects of physical fatigue were also observed at various levels of human system. Therefore, physical fatigue reduction of the new posture was quantitatively validated by physiological measurements.

This paper describes evaluation and examination of a hip disarticulation prosthesis (HDP) with hip joint rotation axis on the lateral side of the HDP socket. Walking experiments using the developed HDP and conventional HDPs which is used by subjects in daily living, were performed for two subjects with hip amputation. The walking motions of these subjects were compared with each other and those of an able-bodied person. While walking with the developed HDP, peculiar lumber compensation movements of conventional HDPs walking at the initial contact of the prosthesis with the floor and during swing phase were reduced, so that it is shown that the developed HDP is effective for improving the walking motion of hip amputee. Finally, in order to make the HDP better, the improved design proposal for the hip joint is proposed and examined on a numerical simulation.

An orthotic ankle joint for lower limb inconvenient person was developed in which external ankle joint moment is generated by MRF (Magneto Rheological Fluid) brake. The brake is a fan-shaped closed vessel filled with MRF and the bane installed in the vessel is moved in the range of 0-70 degrees. The brake moment is generated and shifted by applying magnetic field to the thin flow channel of MRF. In a past trial manufacturing, permanent magnet was moved to near of distant from the MRF flow channel. In this trial manufacturing, the electric coil was used to generate magnetic flux density to the MRF flow in the small gap of the bane, and structure of the brake became simple and compact and response was improved.

With this brake, the control strategy was established based on the finite-state-control. The three states of heel contact, toe-off, and swing-phase were detected by the sensors installed in the orthosis, constructed from foot switches at heel and ball, and potentiometer at ankle joint. With this control strategy, the plantar flexion brake is generated and foot flap is eliminated, and dorsal-flexion ankle joint position is kept during the mid swing phase by generating brake moment at the end of stance phase.

The effect on the gait motion was measured and proved by the gait analysis of the lower limb inconvenient patient wearing this orthosis

The purpose of this study was to show collective effects of plantar flexion braking function while wearing an ankle-foot orthosis (AFO) on whole body movement in stroke gait and to investigate the relations between the change in gait with plantar flexion braking function of the AFO and body functions. For 14 stroke patients, pelvis and upper trunk movements were compared under the following two conditions: in the most improved gait condition (Appropriately controlled plantar flexion while wearing the AFO: AAFO) and in gaits without use of an AFO (No AFO: NAFO). Compared to NAFO, AAFO gaits showed a change in pelvic rotation angle in patients with moderate levels of paralysis who showed the improvement of the heel rocker and ankle rocker functions. This result suggests that plantar flexion braking function while wearing an AFO improved the heel rocker, and the effects altered the ankle rocker function. It was concluded that forward rotation of the pelvis to the non-affected side in initial stance was important for improving hemiplegic gait using the AFO. To increase forward rotation of the pelvis, it is necessary to move the hip and knee joints separatively without synagic pattern.

Gait analysis of two children (CP1, CP2) with spastic cerebral palsy was conducted using three dimensional movement measuring system before and after selective lengthening of lower limb muscles. For evaluation, joint angles and joint moments of the hips, knees and ankles were measured. In CP1 patient with severe spasticity of ankle plantar flexors, range of motion for ankle dorsi flexion and ankle moment showed significant improvement after the operation. In CP2 patient with spasticity of left medial hamstrings, however, decrease ankle plantar flexor peak value after the operation and weakening of knee flexors during stance phase were observed which implies inadequacy of the intervention. Joint moment measurement was found useful for measuring adequate use of joint moment while walking.

The aim of this study is to develop a technique for quantitative evaluation of spastic upper limb in hemiplegic patients. The subjects were 19 hemiplegic patients. Each subject was seated or standing in a resting state, and his or her forearm was flexed 5 times and extended 5 times in each posture through a force-and-torque sensor placed on his or her wrist. The elbow joint angle, torque, and electromyograms of biceps brachii muscle, triceps brachii muscle, and brachioradialis muscle during flexion and extension were measured.

The quasi inertia of forearms and quasi visco-elastic coefficients were estimated with a mathematical model, which consisted of elastic components depending on elbow joint angle and muscle activities, by the least squares method. Then the elbow joint angle were estimated with the obtained quasi inertia and quasi visco-elastic coefficients and compared to the observed angle in order to evaluate the performance of the mathematical model. The elbow joint angle was closely estimated by the mathematical model.

Next, the maximum value of the quasi elastic coefficient during flexion/extension around the elbow joint (k_max) was calculated and compared with the modified Ashworth scale. Our results show that the k_max increased rapidly as the modified Ashworth scale increased. Moreover, logarithm of the k_max strongly correlated to the modified Ashworth scale. The k_max varied depending on patients' posture and mental strain. In conclusion, the mathematical model could represent the time course of the elbow joint angle during the manual muscle test. The k_max would be medically and clinically useful for quantitative evaluation of spasticity in hemiplegic patients.

This paper describes development of a brain-computer interface for severe ALS patients. The BCI has high potential to make useful communication aids for the severe ALS patients who don’t have any motor functions. However, these are few products in practical use for the ALS patients because most of the developments of the BCI system are based on technical seeds and interest. In this project, interview investigations were conducted with the ALS patients at the first stage of the development. According to the result of these investigations, a concept of the BCI system was built as P300 based interface using audible stimulation with Japanese letters. This system allow us to select a letter from Japanese 50 hiragana letters with three steps by choosing one letter from five letters. Experiments with able-bodied people and ALS patients showed possibilities that this system can be practical for communication with the severe ALS patients.

The utility of eye-movements and the eye aperture value as arousal measures was examined to apply for monitoring of bed confined patients. The horizontal and vertical eye-movements and the eye aperture value were obtained in time series by analysis of eye-images during reading. Simultaneously, standard arousal measures including electro-oculogram, electroencephalogram and level of sleepiness as judged by facial-expression, were measured. The reading speed obtained from eye-movements was determined over a range of arousal states. Although, the reading speed had large variations dependent on the content of the reading material, the eye aperture value showed a high correlation with level of sleepiness in all twelve subjects independent of the content. The eye aperture value also showed a correlation with electroencephalogram power in nine subjects. These results indicate that the eye aperture value can be used as a quantitative measure of arousal during a relaxed state, and be a useful addition to the monitoring of arousal and care of bed-confined patients.

Transparent-resinous-ultraviolet-curing-type (TRUCT) Braille signs are becoming more and more popular in Japan, especially when they are printed together with visual characters. These signs are made by screen printing, a technique that can be applied to various base materials. TRUCT Braille signs have begun to be used in public facilities, such as on tactile maps and on handrails. However, there is one serious problem whereby Braille users find it difficult to discriminate TRUCT Braille signs printed on base materials on which their forefingers cannot slide easily. To solve this problem, we invented a soft and thin material finger cover to be used as a TRUCT Braille discriminating assistive tool to reduce friction during discriminating TRUCT Braille. In this study, for the purpose of proposing our finger cover as a TRUCT Braille discriminating assistive tool, we investigated the effect of using the finger cover when discriminating TRUCT Braille. We chose a polyester non-woven fabric as a finger cover as we thought that this material was adequate for our purpose because it has the characteristics of being soft, thin and smooth. We then made a polyester non-woven fabric finger cover. And also we conducted an experiment to compare the readability of TRUCT Braille both when using a polyester non-woven fabric finger cover and when not using it. The subjects were 12 Braille learners with acquired visual impairment, who were asked to read randomly selected characters with and without wearing the finger cover. The results showed that most participants could read TRUCT Braille significantly faster and more correctly with a finger cover than without it, regardless of the base material and dot height. This result suggests that wearing the finger cover enables the Braille learners to read TRUCT Braille more efficiently. The finger cover can therefore be considered as a TRUCT Braille discriminating assistance tool for Braille learners.

The purpose of this study was to clarify the effects of using a low back belt and a transfer board in low back load during person-transfer tasks. Nine healthy young subjects participated in this study, all of whom (mean age, 22.0±1.6 years; mean height, 174.8±4.5 cm; mean weight, 64.4±7.6 kg) were caregivers. One subject (age, 30 years; height, 174 cm; weight, 64 kg) served as the transferee. The subjects performed four different transfers from a wheelchair to a simulated bed : without any assistive devices; with the transferee wearing the low back belt; with the caregiver wearing the low back belt ; and with the transfer board. Extension, lateral and torsion of low back joint moment were calculated by inverse dynamics using data obtained from a three dimensional motion analysis system and six force plates. Results indicated that low back joint extension moments while transferring with caregivers wearing a low back belt and with a transfer board were significantly smaller than that without using any assistive devices (P<0.05). Use of the transfer board appeared to be the most effective of the four methods for minimizing low back load during transfers from wheelchair to bed.

The development of assistive technologies especially pertaining to mobility device has an important impact on the user’s activities of daily living and social participation. The authors have developed a new mobility aid “Tread-Walk” which produced “extending mobility activities,” “maintaining body function” and “natural walking appearance” for older persons. Here, we propose and develop more natural operation system from gait movement. The new system concept is to measure acceleration/deceleration force of each leg by separated belt and to use it for the input signal of change direction. The device, “Tread-Walk 2”, is six-wheeled, permitting the user to walk naturally while a servo motor amplifies normal walking speed. Its main components are a treadmill with two belts, two middle driving wheels and four omni-directional casters. Sensors in the treadmill detect forward and backward of floor reaction forces that are applied to the surface on the belts during walking. These forces of each leg are recognized as signal of user’s change direction and it’s used for turning of vehicle. Rotational speed of the driving wheel motors is controlled by signals from these sensors. Preliminary evaluations suggest that this turning system is both safe and effective for use by middle aged and older adults.

As a result of measurements of comfortable postures and cushion distributions of 37 subjects by using the previously reported experimental bed, it was found that the preferred posture at the supine position has slightly extended back shape compared to the standing position and that the posture at the lateral position has less lateral bending and twisting of spine. Also it was found that the hardness of shoulder cushion at the lateral position was reduced to about 60% of that of the supine position. From these results, 3-layered and 9-divied urethane mattress which consists of soft upper layer, middle layer with the shoulder part softened for the lateral posture, and lower layer with 6 types of hardness to fit for various types of physics was proposed. Portable and adjustable spring mechanism was developed, and the comfortable cushion distributions of 20 youths and 50 elderly people were measured. From these data, regression equations that estimate the comfortable hardness of cushion from a small number of simple anthropometric data were derived in order to select appropriate cushion blocks for individual.