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Volume 47, Issue 1
Displaying 1-3 of 3 articles from this issue
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Paper
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Kengo WAKUI, Yukihiko USHIYAMA, Yuki SATO2023 Volume 47 Issue 1 Pages 45-53
Published: 2023
Released on J-STAGE: September 08, 2023
JOURNAL FREE ACCESSThe present study investigated the change in motor control of lower limb muscles during the incremental cycling exercise by evaluating motor modules extracted from electromyography (EMG) measured before and after electromyography threshold (EMGT). 10 male cyclists performed 10 minutes of continuous incremental pedaling exercise. Cadence and exercise intensity were 90 rpm and 110 W at the start of the exercise, adding 10 W every 30 seconds, respectively. During the exercise, we measured 9 lower limb muscles’ EMG. Then we performed non-negative matrix factorization on EMG matrix to extract the motor modules and cluster analysis using EMG reconstruction accuracy vectors, which indicate the feature quantities of each module set, to evaluate the similarity among module sets extracted from different exercise intensities. As a result, at the exercise intensities above EMGT, the new motor module that is not mobilized below EMGT was activated. The EMG reconstruction accuracy vectors were distributed to different clusters whose borderline was fixed up bordering on EMGT. The above indicates that the rapid increase of EMG amplitude, which is the landmark of EMGT, may result from the change in motor control of lower limb muscles.View full abstractDownload PDF (2340K) -
Suzuka HIGASHIJIMA, Yinlai JIANG, Hiroshi YOKOI, Shunta TOGO2023 Volume 47 Issue 1 Pages 54-62
Published: 2023
Released on J-STAGE: September 08, 2023
JOURNAL FREE ACCESSAlthough humans and robots are capable of catching a ball, it is difficult to catch a ball with a myoelectric prosthetic hand, which is a man-machine cooperative system. The purpose of this study is to observe the catching motion of humans, identify the suitable hand posture for the catching a ball, and apply it to the posture of the robotic hand. As a result of an experiment in which human subjects caught a free-falling ball, the catching postures were classified into five types. It was concluded that the catching posture with the highest catching success rate was the one in which the ball was touched distally to the palm, and that the oppositeness of the thumb and little finger was important. As a result of applying the identified catching posture to the robotic hand, the success rate of the catching a ball with the robotic hand increased dramatically. These results suggest that the user can perform the catching motion by using robotic hand for powered prosthetic hand with opposable thumb and little finger.View full abstractDownload PDF (2057K) -
Takaki KAWASHIMA, Hiroshi ISHIDA, Shinichi FUKUHARA, Tadanobu SUEHIRO, ...2023 Volume 47 Issue 1 Pages 63-70
Published: 2023
Released on J-STAGE: September 08, 2023
JOURNAL FREE ACCESSIt is important to use a device that can objectively evaluate muscle fatigue in subjects during strength training. The purpose of this study was to determine whether the values of torque, electromyogram (EMG), and mechanomyogram (MMG) during isokinetic knee extension show statistically similar fluctuation to each other. Thirty healthy men and women (age 23.7 ± 2.1 years, height 164.9 ± 7.0 cm, weight 56.4 ± 8.0 kg) performed 50 repetitions of isokinetic knee extension (60 deg/s) at maximum voluntary contraction. EMG and MMG were recorded from the vastus lateralis (VL) and vastus medialis (VM), and the root mean square (RMS) and medium power frequency (MDF) were calculated. Torque, VL･VM EMG RMS, VL･VM MMG RMS and VL･VM EMG MDF variability were analyzed using parallel line analysis. The results indicated that only the VL MMG RMS proved to be parallel to the torque (p≥0.05). Clinically, the degree of muscle fatigue may be quantitatively and easily assessed by using VL MMG RMS during strength training, such as knee extension resistance exercise.View full abstractDownload PDF (2070K)
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