著者

Ryoichi Ema Ryota Akagi Taku Wakahara Yasuo Kawakami

出版者

一般社団法人日本体力医学会

雑誌

The Journal of Physical Fitness and Sports Medicine (ISSN:21868131)

巻号頁・発行日

vol.5, no.1, pp.37-46, 2016-03-25 (Released:2016-03-18)

参考文献数

97

被引用文献数

31

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The present review summarizes current evidence and unresolved issues regarding training-induced changes in the architecture of human skeletal muscles. As architectural parameters, we focused on the fascicle length and pennation angle, which are related to force-generating capability of pennate muscles. Cross-sectional studies in sport athletes suggested changes in both the parameters following chronic sport-specific activities. Longitudinal training intervention experiments indicated direct evidence of the plasticity of the two parameters induced by resistance training, but no consensus has been reached regarding the factors influencing those changes. Considering the importance of fascicle arrangement on muscle function, future studies are required to explain the underpinning mechanisms of the adaptation.

著者

Norihide Sugisaki Hiroaki Kanehisa Yasuo Kawakami Tetsuo Fukunaga

出版者

Japan Society of Physical Education, Health and Sport Sciences

雑誌

International Journal of Sport and Health Science (ISSN:13481509)

巻号頁・発行日

vol.3, pp.100-109, 2005 (Released:2008-01-23)

参考文献数

20

被引用文献数

9 10

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This study aimed to investigate the mechanisms of mechanical work and power enhancement of muscle-tendon complex (MTC) in rebound exercise by quantifying in vivo behavior of fascicle and tendinous tissue of human medial gastrocnemius muscle (MG). Subjects jumped on a sledge apparatus using only ankle joint with the following two conditions: plantar flexion without counter movement (PFJ) and rebound jumping from a height of 26 cm (RJ). The behavior of fascicle and tendinous tissue of MG in vivo was determined using ultrasonography. The relative contribution of tendinous tissue to the mechanical work of MTC during plantar flexion phase (PF phase) was 85% in RJ. The maximal mechanical power of tendinous tissue during the PF phase in RJ was about three times greater compared to that in PFJ. There was no significant difference in the mechanical power of fascicle during PF phase between the two conditions, while the mechanical work of fascicle in PFJ was less than that in the PF phase of RJ. In RJ, fascicle was stretched during the dorsiflexion phase. These findings indicated that, in rebound exercise using ankle joint, (1) the enhancement of mechanical work and power of MTC was due to the reuse of elastic energy stored in tendinous tissue during dorsiflexion phase, and (2) fascicles were stretched during dorsiflexion phase.

著者

Takayuki Inami Yasuo Kawakami

出版者

一般社団法人日本体力医学会

雑誌

The Journal of Physical Fitness and Sports Medicine (ISSN:21868131)

巻号頁・発行日

vol.5, no.4, pp.313-317, 2016-09-25 (Released:2016-10-03)

参考文献数

46

被引用文献数

23

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Assessing muscle mechanical properties such as hardness and stiffness has important clinical implications. The use of ultrasound elastography to assess individual muscle hardness or stiffness has been increasing in recent years. Several different ultrasound elastography methods are currently in use, including strain elastography and shear wave elastography, which are capable of capturing the distribution of hardness and stiffness within individual muscles. In the present review, we outline some of the current basic and clinical applications of strain elastography and shear wave elastography, and illustrate how such ultrasound elastography technologies may further advance understanding of individual muscle mechanical properties as well as muscle functions.

著者

Emika Kato Toshiaki Oda Kentaro Chino Toshiyuki Kurihara Toshihiko Nagayoshi Tetsuo Fukunaga Yasuo Kawakami

出版者

Japan Society of Physical Education, Health and Sport Sciences

雑誌

International Journal of Sport and Health Science (ISSN:13481509)

巻号頁・発行日

vol.3, no.Special_Issue_2005, pp.218-225, 2005 (Released:2008-01-23)

参考文献数

19

被引用文献数

14 32

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Flexibility is often evaluated from the joint range of motion (ROM), but the mechanisms underlying gender differences in joint ROM have not been elucidated. The purpose of this study was to investigate the factors influencing the difference in ankle joint ROM between men and women with respect to the extensibility of muscle-tendon complex. Eighteen men (21-26 yr, 66.4±6.0kg, 173.7±7.4cm mean±SD) and 12 women (19-27yr, 52.9±4.8kg, 163.4±4.3cm) participated in this study. Each subject was seated with the knee extended, and the ankle joint was attached to a foot plate, by which the ankle joint was passively dorsiflexed with torque gradually increasing from zero to a value at which the passive loading to the ankle joint was just tolerable for each subject. During the passive loading, real-time ultrasonogram was taken to track the movement of MTJ (muscle-tendon junction of the gastrocnemius medialis and Achilles tendon) as the elongation of muscle belly (dMus). The change of MTC (muscle-tendon complex) length (dMTC) during the passive dorsiflexion was estimated from changes in ankle joint angle. Tendon elongation (dTen) was calculated by subtracting dMus from dMTC. There was no significant difference in normalized passive torque during passive dorsiflexion between men and women. Women were more flexible, i.e., they demonstrated greater dMTC, which was accompanied by greater dTen at lower torque levels. However, dMus was not different between men and women. It was concluded that gender difference in the joint ROM at the ankle reflects more compliant Achilles tendon in women than in men.

著者

Yasuo Kawakami

出版者

一般社団法人日本体力医学会

雑誌

The Journal of Physical Fitness and Sports Medicine (ISSN:21868131)

巻号頁・発行日

vol.1, no.2, pp.287-296, 2012-07-25 (Released:2012-09-11)

参考文献数

63

被引用文献数

5

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The biomechanical features of skeletal muscles are reviewed, with regard to their form and function and anatomical components (fascicles and tendinous tissues). 1) Studies on fascicle architecture are reviewed, highlighting its importance in the force and velocity potentials of the muscle along with its plasticity and muscle-size dependence. 2) The elastic properties of the muscle-tendon unit are described, pointing out the contribution of tendinous tissues as a spring. Functional consequences of tendon elasticity are summarized with respect to exercise performance under mechanically and neurally controlled joint actions, which lead to energy saving of muscle fibers and enhancing the positive work of the muscle. 3) The task-specificity of the muscle as an actuator or a spring and its position dependence (proximal to distal trend of functional divergence) are mentioned. Literature shows that proximal muscles are architecturally designed for actuation and distal muscles are more suited for a spring function. 4) Unique but strange behavior of tendinous tissues, that is seen in stretch-shortening types of movement, is described, suggesting variable elasticity of tendinous tissues that is modulated by muscle activation. 5) Finally, a need to consider multiple muscle-tendon units as a system is introduced to reasonably understand recent findings that otherwise cannot be accounted for. Collectively, it is suggested that the muscle-tendon unit is not only a simple combination of muscle fiber and tendinous tissues acting as actuator and spring, respectively, but also a unit that acts both anatomically and functionally.