筋機能的磁気共鳴画像法を用いた股関節外転運動後の股関節外転筋群の継時的な筋活動の変化

The hip abductor muscles play an important role in postural control. Structural differences in the hip abductor muscles translate to differences in functional activity. This study sought to measure changes in T2 values of the hip abductors after hip abduction exercise over time and to identify variations in activity between the different hip abductor muscle groups. Ten healthy young men (mean age 28.4 [24−32] years) performed 5 sets of 40 repetitions of a hip abduction exercise at 30% maximum voluntary contraction with the right leg. Magnetic resonance imaging was performed before exercise, at intervals during exercise, and at the end of exercise. Subsequently, T2 values were measured for the tensor fasciae latae, gluteus minimus, the anterior, middle, and posterior segments of the gluteus medius, and the upper fibers of the gluteus maximus. T2 values for the gluteus minimus, tensor fasciae latae, and the anterior and middle segments of the gluteus medius were significantly higher at after all exercise compared with before exercise. However, T2 values for the posterior segments of the gluteus medius after 3, 4, and 5 sets of exercise were significantly higher than before exercise. T2 values for the upper fibers of the gluteus maximus after 4 and 5 sets were significantly higher than before exercise. Thus, the variable changes in muscle activity observed in this study were attributable to differences in anatomic structure and reflected intramuscular variation in activity between the hip abductor muscles.首都大学東京学位論文甲第959号副論

筋機能的磁気共鳴画像法を用いた異なる方向への股関節外転運動後の股関節外転筋群の筋活動の経時的変化

首都大学東

A Maximum Muscle Strength Prediction Formula Using Theoretical Grade 3 Muscle Strength Value in Daniels et al.’s Manual Muscle Test, in Consideration of Age: An Investigation of Hip and Knee Joint Flexion and Extension

This study attempted to develop a formula for predicting maximum muscle strength value for young, middle-aged, and elderly adults using theoretical Grade 3 muscle strength value (moment fair: Mf)—the static muscular moment to support a limb segment against gravity—from the manual muscle test by Daniels et al. A total of 130 healthy Japanese individuals divided by age group performed isometric muscle contractions at maximum effort for various movements of hip joint flexion and extension and knee joint flexion and extension, and the accompanying resisting force was measured and maximum muscle strength value (moment max, Mm) was calculated. Body weight and limb segment length (thigh and lower leg length) were measured, and Mf was calculated using anthropometric measures and theoretical calculation. There was a linear correlation between Mf and Mm in each of the four movement types in all groups, excepting knee flexion in elderly. However, the formula for predicting maximum muscle strength was not sufficiently compatible in middle-aged and elderly adults, suggesting that the formula obtained in this study is applicable in young adults only

Numerical analysis and comparison of brass instruments by continuation

International audienceBrass instrument design has long been relying on empirical know-how, build up over the years by the craftsmen. Some relationships between the air-column geometry, the intonation and some attributes of sound color have been formalized through this process by the makers. However, many properties of the instrument, related to timbre, dynamic range, playability, etc. are still very difficult to correlate to the design. Alongside these issues and important questions for the craftsmen, the knowledge in the acoustics of musical instruments has extensively improved in the last decades, benefiting especially from cutting edge engineering methods for the analysis of dynamic systems. In this presentation, we will detail some applications of stability analysis and continuation (Asymptotic Numerical Method), to physical models of trumpets. This approach aims to clarify differences between instruments on the basis of calculated performance descriptors. On a longer term, our goal is to include these technologies in the development of new instruments, by providing some virtual performance analyzers for the design of brass instruments

CONTINUATION OF A PHYSICAL MODEL OF BRASS INSTRUMENT FOR TRUMPET COMPARISONS

International audienceThe system formed by a trumpet player and his/her instrument can be seen as a non-linear dynamical system, and modeled by a biomechanical model of the lips, a non-linear flow equation, and an acoustic impedance of the instrument represented by a superposition of complex modes. Different numerical tools can then be used to study these models in order to understand the effects of the parameters on the behavior of the system. In particular, the modal parameters that describe the impedance are strongly dependent on the geometry and design of the instrument, and the understanding of their influence is therefore of primary interest for a musical instrument maker. An original method of continuation (path-following method) based on the combination of the Harmonic Balance Method (HBM) and the Asymptotic Numerical Method (ANM) is applied to a physical model of the {player-trumpet} system. It consists in studying the evolution of the system where one parameter of the model varies, and enables to calculate bifurcation diagrams for different configurations of the model. Especially, this allows to compare different instruments on the basis of quantitative descriptors computed from the continuation outputs