The gluteus medius muscle is an important muscle that dampens and stabilizes the lateral inclination of the pelvis during one-leg standing and walking. Defining the internal structure of the gluteus medius muscle, muscle output and electromyographic waveform characteristics leads to appropriate improvement of the examination method in clinical practice and better interpretation of the examination data, and can contribute to improvement and prevention of functional disorders such as instability and fall. Macroscopic anatomical investigations revealed that the aponeurosis was present inside the gluteus medius and divided into anterior and posterior bundles. In the measurement of muscle cross-sectional area and electromyography at the time of maximum abductor abduction, the data were estimated that the anterior fiber bundle mainly contributed to the hip extension position and the posterior fiber bundle mainly contributed to the hip flexion position. The myoelectric potentials of both fiber bundles of the gluteus medius during walking had individual characteristics of the subjects, but reflected the characteristics at the time of maximum muscle strength.
A major factor for increased fall risk is the loss of muscle strength in the lower limb. However, current methods for measuring the muscle strength of the lower limb involve the use of large-scale measuring equipment. Therefore, an easier method using a home-based device for measuring the muscle strength is required. In the present study, relation between muscle strength and daily gait parameters are calculated as a correlation analysis. Gait movement of 43 healthy elderly participants in both indoor and outdoor areas is measured using inertial sensors on ankles. Thereafter, gait parameters are calculated as amplitude parameters （ such as maximum and minimum values ） and frequency parameters （ such as maximum and median values ） of acceleration and angular velocity waveform. Correlation coefficient between each parameter and lower limb muscle strength were calculated. Effective parameters to estimate muscle strength in the lower limb were selected and discussed. As a result, the highest correlation coefficient observed between muscle strength and the parameters was 0. 47 for indoor walking and 0. 49 for outdoor walking. These values of correlation coefficient are similar to those reported in a previous study. Furthermore, we selected different parameters for indoor and outside gait. The angular velocity parameter by ankle flexion was selected for indoor gait, whereas, the lateral acceleration parameter was selected for outdoor gait.
In ball sports, players often move their gaze by combining eye and head movements. In this study, this combination of eye and head movements is defined as � visual strategy � . Thirteen female university students participated in this study and coincident timing accuracy was measured by manually pressing a button coinciding with the arrival of a ball. In the experiment, the participants looked at the ball from two different angles of 90 degrees （ lateral ） and 0 degrees （ frontal ） relative to the moving direction of the ball. Ball speeds were also set at two different speeds ： Slow and Fast. Eye movements were recorded at a sampling rate of 25 Hz during a coincident timing task. It is thought to be important to select and execute the optimal visual strategy in order to carry out accurate coincidence timing. The results showed that the coincident timing accuracy for the 90 degrees condition was significantly higher than that for the 0 degrees condition. It was also revealed that at the 90 degrees condition, the subjects changed their visual strategies according to the speed of
The purposes of this study were 1 ） to clarify the difference in shear stress applied to the proximal myotendinous junction and musculotendon dynamics between the biceps femoris long head （ BFlh ） and semimembranosus （ SM ） during the late swing phase of high-speed running, and 2 ） to assess the effects of musculotendon parameters such as insertion points, tendon slack length, optimal muscle fiber length, pennation angle at optimal muscle fiber length, and maximal isometric force in the hamstring muscles on muscle force and shear stress of the BFlh and SM. Ten soccer players performed running trials at maximum effort. A three-dimensional musculoskeletal model with 43 Hill-type musculotendon actuators of the right leg was used to compute the musculotendon dynamics during the late swing phase of high-speed running. While peak muscle force of the BFlh was significantly smaller than that of the SM, the BFlh had significantly higher peak shear stress and musculotendon elongation velocity at peak shear stress than the SM. The results indicate that the BFlh has a higher risk of injury at the proximal myotendinous junction during the late swing phase of high-speed running. Additionally, shorter tendon slack length in the BFlh and SM most affected the increase of muscle force and shear stress.
近年, 重度肢体不自由者が支援機器を用いるときの入力法として, 視線入力が一般化してきている. 現在の視線入力のユーザインタフェースであるオンスクリーンキーボードは, パソコンに実装されている一般的な方法を踏襲しており, 必ずしも眼球運動の特性・視覚認知特性を考慮して設計されていない. そこで本研究では, 視線入力に適したインタフェース設計の基礎研究として, 現在一般的な視線入力法を用いた文字入力で生じる視線停留の 「場所・時間」 「入力キーからの相対位置」 を明らかにすることを目的とした. キー形状は円形と正方形の2つとし, キー形状ごとにキーボードの使用性に関してアンケート調査した. 視線停留は, その継続時間によって 「短時間停留」 「長時間停留」 「文字入力」 の3つに分類し, 区分ごとに発生率および原点を入力キーとする分布を調べた. その結果, インタフェースの使用性は, キー形状によらず低かった. 視線停留は, 長時間停留と文字入力が 「入力するキー」 「その周辺キー」 に集中し, 短時間停留がキーボード上の広範囲で発生した. 円形キーの場合, 長時間停留と文字入力はターゲットキー周辺の比較的狭い領域で発生する傾向がみられた.
The purpose of this study was to clarify the success factors of snatches in elite Japanese female weightlifters from the viewpoint of biomechanics. Data were collected at the All-Japan championships. The data in this study included successful and unsuccessful （ due to a backward barbell drop ） snatch lifts achieved using the same weights by the same lifter. This study analyzed the snatch motion and barbell trajectory of 11 lifters. The results revealed significant differences in the barbell backward and forward displacement and forward peak velocity, which were significantly smaller in a successful snatch lift than in an unsuccessful lift （ p < 0. 01 ) . The COM forward displacement and forward peak velocity in a successful snatch lift were significantly smaller than in an unsuccessful lift （ p < 0. 01 ) . Furthermore, there was no significant difference in the maximum barbell height between successful and unsuccessful lifts. Based on these findings, we concluded that maximum barbell height is not a success factor for snatches in elite female Japanese weightlifters. Decreased barbell forward and backward displacement in the second pull phase to catch each phase and decreased COM forward displacement during drop under the barbell increase the probability of success without a backward barbell drop in the snatch motion.
We attempted to clarify the mechanical function of bi-articular muscles in the lower limb in the toe landing motion which enables the running motion. In the present study, the main working muscle was first clarified by electromyography analysis. An experimental analysis was subsequently performed using a real machine model, taking the protagonist muscle into consideration. The results of the electromyography analysis clearly demonstrated that stability of the body trunk involved switching the activity of the antagonistic pair of bi-articular muscles in the femur, suggesting a parallel link function. Based on this, an experimental analysis was performed using a real machine model with bi-articular muscles in the lower limb linked in parallel. The stability of the center of gravity of the model during dynamic motion due to switching of the muscle activity confirmed the parallel linkage, thus clarifying the involvement of the bi-articular muscles in the lower limb in body trunk stability at the time of toe landing.
SUI （ Stress Urinary Incontinence ） is a typical quality of life disease in women, and it can cause symptoms of unexpected urine leaks when abdominal pressure rises, such as coughing and sneezing. It is mainly caused by relaxation or damage of PFM （ Pelvic Floor Muscles ） due to obesity, aging and childbirth and it is considered that strengthening of PFM is effective for prevention. Training methods such as Kegel gymnastics have been devised so far, but these methods need expert guidance and time for training. Individual differences of pelvis shape and alignment affect to the effect of training PFMs. In order to solve this problem, we proposed a method to estimate the individual optimal training posture, by defining 11 postures that can be taken in daily life and calculating the PFM activation of each posture with the individualized musculoskeletal model. Moreover, the proposed method was evaluated by comparing with the measured values of PFM activation in each posture. As a result, a positive correlation with the calculation result was confirmed in 3 subjects out of 6, suggesting the validity of this method.
The knee braces are widely used for rehabilitation and treatment in the knee osteoarthritis patient. The purpose of this study is to establish biomechanical analysis method of the knee brace by integrating a finite element analysis model of the knee joint in the knee osteoarthritis patient, a mechanical model of the knee brace, and a walking generation model representing human walking. The finite element analysis model of the knee joint was constructed based on medical imaging technology, and the joint contact force obtained from the walking generation model was assumed to be a boundary condition in the finite element analysis. This study evaluated the treatment of three types of knee braces ： valgus knee brace, rotation knee brace and valgus-rotation knee brace. These knee brace models were simply represented by moment forces affecting the femur. The contact pressure distributions occurring on the medial and lateral meniscus at three phases during walking were calculated by the proposed models. It was found that the contact pressure distribution of the medial meniscus while wearing all the knee braces reduced, compared with that without the knee brace.
