Tadashi Masuda

• PhD
• Professor (Full) at Fukushima University

Aim Factors related to instrumental activities of daily living disability in older adults with knee osteoarthritis are unclear. This study aimed to examine the discriminatory accuracy for the presence of instrumental activities of daily living disability in older adults with knee osteoarthritis by combining two factors of gait ability and pain stat...

Background and objectives: Many patients develop a prolonged decrease of muscle strength after total hip arthroplasty (THA) despite their reconstructed hip joint. Physical exercise combined with branched-chain amino acid (BCAA) supplementation has been reported to improve muscle strength in elderly persons with sarcopenia. However, the effect of B...

Display number: PO-E-23-SAT1 The present study showed that BCAA supplementation combined with muscle strengthening exercises showed significant interaction on knee extension strength on the contralateral side and upper arm cross-sectional area. In addition, the improvement rate of knee extension strength on the operated side was significantly high...

Background: Improving lower limb muscle strength is important in preventing progression of osteoarthritis (OA) and its symptoms. Exercise with branched-chain amino acid (BCAA) supplementation has been reported to affect protein anabolism in young and elderly persons. However, few studies provided daily BCAAs for patients with OA. Objective: This st...

Background: Joint angle data from healthy subjects are necessary as baseline information. Objective: To analyze the problems of patients who struggle with activities of daily living (ADL) due to restricted range of motion and to provide ADL guidance based on objective data. Method: An electromagnetic three-dimensional tracking system (FASTRAK)...

[Purpose] The importance and effect of hip joint geometry on hip abductor muscle strength are well known. In addition, other perioperative factors are also known to affect hip abductor muscle strength. This study examined the relative importance of factors affecting hip abductor muscle strength after total hip arthroplasty. [Subjects and Methods] T...

[Purpose] The correlations of peak vertical ground reaction force and sagittal angles during single-leg lateral jump-landing with noncontact anterior cruciate ligament injury remain unknown. This study aimed to clarify the correlations between kinematics and impact force during lateral jump-landing. [Subjects and Methods] Twenty active males were i...

This study examined the effects and feasibility of a twice-weekly combined therapy of branched-chain amino acids (BCAAs) and exercise on physical function improvement in frail and pre-frail elderly people requiring long-term care. We used a crossover design in which the combination of exercise and nutritional interventions was carried out twice a w...

[Purpose] Physical development, foot morphology, and toe contact of children aged 3 to 5 years were assessed in order to investigate the relationships between body and foot morphology and the incidence of the condition known as “floating toe”. [Subjects] A total of 198 children, aged 3 to 5 years old, participated in this study. [Methods] Height an...

Myosins are typical molecular motor proteins that convert the chemical energy from the ATP hydrolysis into mechanical work. The fundamental mechanism of this energy conversion is still unknown. To explain the experimental results already obtained, Masuda has proposed a hypothesis called the "Driven by Detachment" theory for the working principle of...

Angles of the shoulder joint are usually defined in each of the sagittal, coronal, and horizontal planes passing through the center of the shoulder joint. One of the problems with this method is the difficulty of describing some positions of the shoulder joint such as the anterolaterally elevated position. In 2005, the International Society of Biom...

Understand the process of amino acid fermentation as a comprehensive system is a challenging task. Previously, we developed a literature-based dynamic simulation model, which included transcriptional regulation, transcription, translation, and enzymatic reactions related to glycolysis, the pentose phosphate pathway, the tricarboxylic acid (TCA) cyc...

Purpose: The aim of this study was to show highly reliable normal values and three-dimensional characteristics for final range of motion during active movements of the upper extremity joints, and to develop a database from healthy participants, with the advantage of this database lying in the methods of defining shoulder axial rotation angle and o...

Myosins are typical molecular motor proteins, which convert the chemical energy of ATP into mechanical work. The fundamental mechanism of this energy conversion is still unknown. To explain the experimental results observed in molecular motors, Masuda has proposed a theory called the "Driven by Detachment (DbD)" mechanism for the working principle...

The Montreal Affective Voices (MAVs) consist of a database of non-verbal affect bursts portrayed by Canadian actors, and high recognitions accuracies were observed in Canadian listeners. Whether listeners from other cultures would be as accurate is unclear. We tested for cross-cultural differences in perception of the MAVs: Japanese listeners were...

[Purpose] Balance training lowers the risk of falling in the elderly, but it is not known which specific muscles should be strengthened. The purpose of this study was to determine associations between fatigue of individual muscle groups in the lower limbs and balance. [Subjects and Methods] We tested 42 lower limbs of 21 healthy young adults with n...

Previous research has shown that mastication reduces shifts in the center of gravity of persons standing still. The present research was conducted to determine whether mastication improves reactive balance in the standing position in response to unanticipated external disturbances. The subjects were 32 healthy male adults (mean age 21.1 years, stan...

Objective Although language and culture are different in each area in the world, how does culture affect the recognition of nonverbal emotional vocalisations? A previous study on non-verbal emotional vocalisations has shown a cross-cultural effect in Western and African participants. However, nobody has ever investigated the cross-cultural differen...

Highly reliable information on the range of motion (ROM) required to perform activities of daily living (ADL) is important to allow rehabilitation professionals to make appropriate clinical judgments of patients with limited ROM of the upper extremity joints. There are, however, no data available that take full account of corrections for gimbal-loc...

本研究の目的は，動的な筋収縮時に記録した表面EMGを正規化するために基準として用いる等尺性の最大随意収縮（MVC）試技を，どのような関節角度（筋長）で実施し表面EMGを記録するのが適切であるかを明らかにすることであった．七人の健康な成人男性が被験者として，等速性筋力測定装置を用いて，短縮性と伸張性および等尺性の肘関節屈曲伸展運動を行った．それらの試技の間に，肘関節の角度，角速度および肘関節まわりのトルクと，上腕二頭筋と上腕三頭筋の表面EMGを記録した．等尺性収縮中のトルクと表面EMGおよび動的収縮中の表面EMGは，動的収縮中のトルクを推定するために用い，推定されたトルクと動的収縮中のトルクとの差から推定誤差が求められた．推定誤差を小さくするという規準のもと，CONでは筋長が小さくなる関節角度...

The purpose of this study was to analyze age-related movement smoothness changes in the lower extremity joints during load lifting. A total of 10 young and 13 elderly subjects participated in the study. Infrared reflective markers were attached to body landmarks in each subject. While the subjects stood on force plates and lifted a box, the marker...

Kinesins are molecular motors that unidirectionally move along microtubules using the chemical energy of ATP. Although the core structure of kinesins is similar to that of myosins, the lever-arm hypothesis, which is widely accepted as a plausible mechanism to explain the behaviors of myosins, cannot be directly applied to kinesins. Masuda has propo...

There is a large superfamily of myosins, which play various fundamental roles in cellular motility. In this superfamily, most of myosins, including myosins II and V, move to the barbed end of an actin filament, whereas myosin VI was found to move in the opposite direction to the pointed end. Although myosin VI has structural differences compared wi...

Myosins are molecular motors that convert the chemical energy of ATP into mechanical work called a power stroke. Class II myosin engaged in muscle contraction is reported to show a "loose coupling phenomenon", in which the number of power strokes is greater than the number of ATP hydrolyses. This phenomenon cannot be explained by the lever-arm hypo...

During an upright stance of humans, it is usually assumed that a stiffer ankle joint contributes to stabilize the stance. To show that under certain conditions a stiffer ankle joint can reduce the stability, the frequency responses of the moment and the angle of the ankle joint against external disturbances caused by random horizontal translations...

The Euler/Cardan angles are commonly used to define the motions of the upper arm with respect to the trunk. This definition, however, has a problem in that the angles of both the horizontal flexion/extension and the axial rotation of the shoulder joint become unstable at the gimbal-lock positions. In this paper, a new definition of the axial rotati...

Total hip arthroplasty (THA) is one of the most effective treatments for osteoarthritis and rheumatoid arthritis. Dislocation of the femoral head from the acetabular socket is a major problem of THA. To prevent dislocation, it is important to know the range of motion (ROM) after THA. Although various studies on the ROM were carried out, there exist...

Six normal male and one Parkinsonism male adults were participated in this study. These subjects walked five times in three different speeds i.e. slow, normal and fast, on five meter length way. Two sensor-units for detecting tri-axial angular velocity were made with six miniature gyroscope sensors. Two sensor-units were mounted on the lateral side...

In order to identify the group of muscles related to deterioration of balance function in the elderly, an exploratory experiment was conducted to analyze and study the influence of lower limb muscular fatigue on balance disturbance in the stable upright position. A stabilometer and a multipurpose muscle function testing and training system were use...

Dynamic flexion and extension of the trunk in the sagittal plane were performed slowly by five normal males with straight knees and bent back under three load conditions. The activity of the erectores spinae muscle was recorded by electromyography and the mean amplitude of the EMG of the muscle per 05 s was calculated. The movements of the acromidn...

The velocity storage integrator does not play a dominant role in the postural response to vertical visual cues; more likely, retinal slip provides the main driving force. By contrast, sideways eye movement can drive the velocity storage integrator and preserve a gravitational cue, which would be observed as a cross-coupling effect on the postural r...

Soft tissue artefact (STA) is caused by the relative displacement of markers or sensors mounted on the skin surface with respect to the underlying bones, and is a major source of error in the kinematic measurement of human movement. In particular, the humeral axial rotation (HAR) is affected by STA. The aim of this study was to propose a method for...

To examine whether occlusion status contributes to improvement of postural balance. Thirty healthy adolescents (15 males and 15 females; mean age, 20.3; standard deviation (SD) 1.6 years) with no equilibrium or stomatognathic function abnormalities were examined. Occlusion is a term meaning "jaw clenching." Occlusion status was evaluated by measuri...

The purpose of this study was to objectively evaluate the fit of sockets for trans-tibial stumps in order to establish a guideline for use in the automated production of prosthetic sockets. Subjects were 24 trans-tibial amputees. Using a CAD/CAM system, 11 parameters regarding the 3D shape of the stumps and the sockets were objectively evaluated. A...

To evaluate the utility of our newly devised method (incremental stand-up exercise-load) to determine features of general endurance in hemiplegic patients. Participants were 15 healthy adults and 15 hemiplegics, with 13 men and 2 women in each group. To evaluate endurance, the subjects were required to assume a sitting position on a bed for 3 minut...

The purpose of this study was to estimate the structure of active motor units through an inverse analysis of surface EMG. Firstly, the surface EMG (motor unit action potentials; MUAPs) were recorded from the biceps brachii by an electrode array which was perpendicularly arranged in the muscle fiber direction. The depth and intensity of active motor...

To analyze the load on the lumbar spine and the motion pattern of a body during a backhand stroke when playing tennis, kinematic and kinetic data of eleven amateur tennis players were collected. Each subject performed one-handed and double-handed strokes at low, medium, and high racket speeds. The three-dimensional motion of the strokes was optical...

This study focused on the effect of regularity of environmental stimuli on the informational order extracting function of human brain. The regularity of environmental stimuli can be described with the exponent n of the fluctuation 1/f(n). We studied the effect of the exponent of the fluctuation in the inter-stimulus interval (ISI) on the elicitatio...

Control of the standing posture of humans involves at least two distinct modes of operation to restore the body balance in the sagittal plane: the ankle strategy and the hip strategy. The objective of the study was to estimate the contribution of vestibular, visual and somatosensory feedbacks to these distinct strategies. The body dynamics was desc...

The primary motor cortices controlling foot movement are located on opposite sides of the longitudinal fissure. As a separation of closely located activity sources is not successful, the possibility of bilateral activation for lower limb movement remains undetermined. We therefore examined cerebral activity during unilateral foot movement to invest...

The disuse syndrome is caused by low physical activity especially in the elderly. If muscles are not used for a long time, their strength will decrease. Weakened muscles accelerate reduced daily life activity. To overcome the disuse syndrome, appropriate training must be delivered with proper timing. The purpose of the present study was to clarify...

Although a large number of studies have been conducted into negative influences on motor function after long-term muscle disuse, little is known about the effect of short-term muscle disuse and its mechanism. Moreover, the aspect of functional decrease during short-term muscle disuse may be different at high and low levels of muscle output. Knowled...

There is a long-running debate on the working mechanism of myosin molecular motors, which, by interacting with actin filaments, convert the chemical energy of ATP into a variety of mechanical work. After the development of technologies for observing and manipulating individual working molecules, experimental results negating the widely accepted 'le...

We studied the mechanism for slowing surface electromyography (EMG) during fatiguing contraction using superimposed M-wave analysis. Seven healthy male subjects exerted 60% maximum voluntary contraction of isometric abductions in the left first dorsal interosseous muscle (FDI) until exhaustion. Simultaneously with voluntary contractions, the ulnar...

The purpose of this study was to examine the effects of short-term immobilization on the maximum voluntary contraction (MVC) force. The first dorsal interosseus (FDI) of 10 healthy male adults was immobilized for 1 week using casting tape. Atrophy of the muscle was estimated from a cross sectional view of magnetic resonance images (MRI). To clarify...

The purpose was to examine the relation between voluntary muscle activation and neuromuscular endurance of individual subjects based on the pattern of surface electromyography (EMG). The voluntary muscle activation was estimated from the relation between voluntary force and tetanic force superimposed on the voluntary force (twitch interpolation tec...

The purpose was to examine the relation between voluntary muscle activation and neuromuscular endurance of individual subjects based on the pattern of surface electromyography (EMG). The voluntary muscle activation was estimated from the relation between voluntary force and tetanic force superimposed on the voluntary force (twitch interpolation tec...

We studied the neuromuscular adaptation that occurs with aging by comparing changes in surface electromyography (EMG) variables from the tibialis anterior muscle in 12 young (21.4 +/- 1.7 yr. old) and 13 older subjects (70.8 +/- 3.1 yr. old). EMG variables such as the muscle fiber conduction velocity, median frequency, and averaged rectified value...

We studied the neuromuscular adaptation that occurs with aging by comparing changes in surface electromyography (EMG) variables from the tibialis anterior muscle in 12 young (21.4 ± 1.7 yr. old) and 13 older subjects (70.8 ± 3.0 yr. old). EMG variables such as the muscle fiber conduction velocity, median frequency, and averaged rectified value were...

The power spectrum is well known to shift to lower frequencies and increased amplitude with progressing of fatigue. The increase in amplitude depends on motor unit recruitment. The frequency shift depends on the reduction in muscle fiber conduction velocity. Neuromuscular function was evaluated noninvasively by observing electromyography (EMG) duri...

Introduction The study of human brain mechanism in cognitive science has become active recently due to the advancement of non-invasive brain measurement methods. In some experimental studies, reaction time tasks like button press have been used to analyze cognitive performance. However, few studies have been done to examine the human brain mechanis...

Before using electromyographic (EMG) variables such as muscle fiber conduction velocity (MFCV) and the mean or median frequency (MDF) of an EMG power spectrum as indicators of muscular fatigue during dynamic exercises, it is necessary to determine the influence of a joint angle, contraction force and contraction speed on the EMG variables. If these...

The distribution of innervation zones was investigated in 3 subjects for 17 muscles and 8 muscle groups in the upper and lower limb, by detecting bi-directional propagation of motor unit action potentials (MUAPs) with the multichannel surface electrode array. Clarification of the distribution of innervation zones depended on the ease in detecting t...

The purpose of this study was to evaluate the neuromuscular adaptation that occurred with aging, by comparing young and aged subjects with respect to changes in surface EMG from the tibialis anterior muscle during fatiguing contractions. EMG variables such as the averaged rectified value (ARV), median frequency (MDF), and muscle fiber conduction ve...

In recent years SQUID (Superconducting Quantum Interference Device) technology has developed rapidly in both sensitivity and number of recording channels. Biomagnetic measurements based on SQUID technology are considered to have great potential in the analysis of brain and heart functions. They are also applicable to skeletal muscles and may provid...

The purpose of this study is to examine the validity of muscle fatigue evaluation using maximum voluntary torque (MVT), and to identify the dependence of individual's tolerance for fatigue on the capacity to exert MVT. In 14 young male subjects (10 regular exercisers and 4 sedentary), MVT was measured during isometric knee extension, and voluntary...

MEG recording has made it possible to identify activities in the sensorimotor cortex. A few studies have been done about a self-paced voluntary movement [1][2][3], an event-related activity with sensory guidance [4] and the functional organization [5][6]. However, it is still not clear how the temporal feature of each activity in the primary motor...

We have developed multichannel electromyography (EMG) for detecting the propagation of motor unit action potentials [1]. With this non-invasive technique it becomes possible to define motor endplate regions based on the source of the propagation. The measurement of muscle fiber conduction velocity has also become possible (Fig. 1). The purpose of t...

The depth and intensity of equivalent current dipoles that can create the surface potentials of active motor units in human skeletal muscles are estimated through an inverse analysis of surface electromyographic (EMG) potentials in an attempt to measure detailed muscular activity non-invasively. The inverse analysis is conducted by repetition of fo...

The human primary motor cortex during a unilateral finger reactive movement to visual stimuli was examined by magnetoencephalography (MEG) measurement. The brain activity related to movement execution (the motor activity contralateral to the movement side) was estimated based on movement onset conditions and reaction times. The movement onset condi...

The purpose of this study was to investigate the effect of short periods of isokinetic resistance training on muscle use and strength. Seven men trained the right quadriceps femoris muscles (QF) 9 d for 2 wk using 10 sets of 5 knee extensions each day. Isometric and isokinetic torques of QF were measured at six angular velocities. Cross-sectional a...

To develop new non-invasive ways of analyzing human skeletal muscle function, biomagnetic measurement was applied to the vastus lateralis and vastus medialis of 3 healthy adult males using a 64 channel superconducting quantum interference device system. Discharges from single motor units were detected by simultaneously recorded surface electromyogr...

The effect of contraction types on muscle fiber conduction velocity (MFCV), median frequency (MDF) and mean amplitude (AMP) of surface electromyography was examined in the vastus lateralis of 19 healthy male adults. The subjects performed knee extension both statically and dynamically until they were exhausted. The static contraction was a sustaine...

Average muscle fibre conduction velocity (CV) measured with multichannel surface electrodes decreases with time during sustained isometric contraction. Based on this property, CV is considered a candidate for an objective index to localized muscular fatigue. CV, however, also depends on many other factors that include muscle temperature and volunta...

The in vivo analysis of bioelectric and biomagnetic potentials supplies valuable information for localization of current source. Only a few attempts, however, have so far been made at inverse analysis of surface EMG. The purpose of this study is to estimate functional and structural parameters of the motor unit (MU), e. g. depth and strength of the...

Surface myoelectric potentials are detected through the geometrical structures which lie between the active motor units and recording surface electrode, such as inhomogeneous muscle tissue, subcutaneous tissue and skin surface. The method of image is simple simulation method for myoelectric potentials. This method, however, has limitations in appli...

By detecting the propagation of motor unit action potentials (MUAPs) with a linear surface electrode array we can locate the innervation zones (motor endplate regions) and estimate the muscle fibre conduction velocity. This technique has mostly been applied to muscles in the upper and lower extremities. The purpose of the present study was to clari...

We presented 2 cases of complications, bronchospasm and abdominal distention during post operative epidural analgesia with morphine. Case 1: A 56 year old female. She was given 12 ml of 1% lidocaine and 3 mg of morphine hydrochloride through a catheter dwelling between Th4 and Th5 for postoperative pain. About 5 hours after the administration, the...

A neural network model of competitive learning was proposed. In this model, output cells in the network were self-organized to represent the distribution of input pattern vectors. The self-organization was based upon a generalized energy function. The network was mathematically proved to converge to the global minimum of the energy function when th...

The purpose of this study was to investigate the laterality of muscle fiber conduction velocity in biceps brachii for badminton players, who have stronger arm in the handedness side for long term training. The muscle fiber conduction velocity was calculated from the propagation time of the action potentials along the muscle fibers and the electrode...

The average conduction velocity of human skeletal muscle fibers measured with multicontact surface electrodes has been reported to increase with the muscular contraction force. This increase of the conduction velocity is considered to be a manifestation of the size principle of motor units: the larger motor units with higher recruitment thresholds...

In skeletal muscles which have muscle fibers running parallel to each other, motor unit action potentials (MUAPs) arise from the innervation zones (motor end-plate regions) and propagate bidirectionally along the muscle fibers. Using this property, it is possible to estimate the location of the innervation zones by recording the EMG signals simulta...

A technique was developed to identify the propagation pattern of high-threshold motor unit action potentials (MUAPs) in human skeletal muscles. A linear surface array and a selective needle electrode were used simultaneously for detection of myoelectric signals during a constant-force isometric voluntary contraction. The needle signals were decompo...

Two types of multicontact surface electrodes were used to define the distribution of innervation zones (motor end-plate regions) in human skeletal muscles: a linear array electrode and a two-dimensional grid electrode. These electrodes detected motor unit action potentials (MUAPs) propagating along the muscle fibers during a voluntary contraction a...

The average muscle fiber conduction velocity (CV) measured with multicontact surface electrodes has been reported to increase with the contraction force. To understand this behavior better, we studied the relationship between the recruitment threshold and the muscle fiber CV of single motor units (MUs). Myoelectric signals were recorded simultaneou...

An electrical activity associated with the excitement of muscle fibers arises from the myoneural junctions located at the middle length of the fibers and propagates to the both ends. This propagation can be detected with a multi-electrode array placed on the skin surface. Therefore, the position of the myoneural junctions, or of the innervation zon...

A grid electrode with closely spaced contacts was developed to measure the spatial distribution of motor unit action potentials on a skin surface. This electrode was used to estimate the configuration of innervation zones. The derived action potentials showed waveforms originating from the middle length of the muscle belly and propagating bidirecti...

Motor unit action potentials were derived with multiple surface electrodes from the biceps brachii of 3 healthy adults. The electrodes comprised a 9-by-16 grid array of small gold-coated metal contacts attached to a cylindrical plate. The spacing of the contacts was 5.08mm in the direction of muscle fibers and 2.54mm in the muscle circumference. Wi...

The relationship between muscle fibre composition and fibre conduction velocity was investigated in 19 male track athletes, 12 sprinters and 7 distance runners, aged 20-24 years, using needle biopsy samples from vastus lateralis. Cross sectional areas of the fast twitch (FT) and slow twitch (ST) fibres were determined by histochemical analysis. The...

Motor unit action potentials (MUAPs) propagate bidirectionally along the muscle fibers. Whether or not the propagation of MUAPs can be detected with surface electrodes depends on the configuration of muscle fibers and innervation zones. The authors clarified the muscles from which the propagation of MUAPs is detectable with a surface electrode arra...

The average conduction velocity of muscle fibers measured with a surface electrode has been reported to increase with the level of contraction force. To clarify the factors causing this increase, the authors decomposed the interference surface EMG signal into its constituent motor unit action potentials and compared the average conduction velocity...

A method was proposed for detecting and rejecting motion artifacts superimposed on myoelectric (ME) signals which are used in the estimation of muscular activity, in the control of powered prostheses, and in other applications. The method is based on the propagation characteristics of motor unit action potentials derived with multiple surface elect...

Propagation of single motor unit action potentials (MUAPs) was detected by surface electromyography. Sixteen EMG signals were simultaneously recorded by a linear bipolar electrode array placed along the longitudinal axis of the biceps brachii. EMGs were obtained from 8 healthy adults at 10-40% of the maximum contraction. Single MUAPs were extracted...

Without Abstract

Three factors influencing the accuracy of the muscle fibre conduction velocity estimates were studied. They were the recording position, the interelectrode distance and the misalignment of the electrode with respect to the muscle fibres. Experiments were performed on the biceps muscle of a normal subject. Bipolar recordings were made simultaneously...

The activity of the leg and abdominal muscles in trunk flexion and extension was investigated with reference to the sudden decreases and increases of the erectores spinae activity. The movement was performed under conditions with and without an additional load, and with and without fatigue. Surface EMGs were recorded from the erectores spinae, the...

Action potentials of single motor units were detected by a linear surface electrode array placed perpendicular to the longitudinal axis of the biceps brachii. Twelve myoelectric signals were derived simultaneously from a voluntarily contracting muscle. Using a visual feedback control, 3 subjects produced spike trains of single motor unit action pot...

A linear surface electrode array placed along the muscle fibers detects motor unit action potentials propagating bilaterally to the tendons. The location of the propagation source is presumed to mark an innervation zone. We developed a computer program, which automatically determined the potential source by applying a correlation calculation and a...