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Masakazu Matsuoka, Hiroshi Kunimura, and Koichi Hiraoka

gastrocnemius muscle ( Diener, Horak, & Nashner, 1988 ; Horak, Diener, & Nashner, 1989 ; Horak & Nashner, 1986 ; Nardone et al., 1990 ). The middle-latency response is mediated by Group II afferents ( Grey, Ladouceur, Andersen, Nielsen, & Sinkjær, 2001 ; Schieppati & Nardone, 1997 ). The latency of the long

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Thomas J. Sherriff, Kyle T. Ebersole, and David J. Cornell

Key Points ▸ Firefighters display a variety of movement compensations during an overhead squat. ▸ Restricted gastrocnemius muscle length is associated with the movement efficiency of firefighters. ▸ Interventions to lengthen gastrocnemius musculature should be utilized among these tactical athletes

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Sahar Boozari, Mohammad Ali Sanjari, Ali Amiri, and Ismail Ebrahimi Takamjani

CMJ involves the stretch-shortening cycle and is a functional test to assess lower-extremity performance. 12 Previous studies on the effects of KT during CMJ have used different methods of KT application on different muscles. 5 , 6 , 8 – 11 Among the muscles involved in CMJ, the gastrocnemius has a

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Tomonari Takeshita, Hiroaki Noro, Keiichiro Hata, Taira Yoshida, Tetsuo Fukunaga, and Toshio Yanagiya

gastrocnemius medialis (GM) while running was higher in RFS runners rather than in FFS runners. In addition, Suzuki et al 16 demonstrated that GM fascicle length was longer in the RFS than the FFS throughout the gait cycle. While the difference in muscle–tendon kinematics has been investigated between the FFS

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Diego Alonso-Fernandez, Yaiza Taboada-Iglesias, Tania García-Remeseiro, and Águeda Gutiérrez-Sánchez

proven in this preventive and rehabilitative aspect, but its effects on muscle architecture have not yet been studied. Therefore, our purpose was to assess the effects that the HDE may have on FL, PA, and MT of the lateral gastrocnemius (LG) and medial gastrocnemius (MG) muscles, due to the high

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Kimberly Somers, Dustin Aune, Anthony Horten, James Kim, and Julia Rogers

elongation of equal parts of both tendon and muscle fascicles, whereas post stretching ROM gains were secondary to changes in elastic properties of the gastrocnemius muscle rather than the tendon. During self-myofascial release, pressure, undulation, movement, and friction are applied to muscle tissue

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Masatoshi Nakamura, Shigeru Sato, Ryosuke Kiyono, Nobushige Takahashi, and Tomoichi Yoshida

represent individual passive muscle stiffness apart from the passive stiffness of the MTU. 13 – 15 Previous studies on shear elastic modulus measurement reported that the shear elastic moduli of gastrocnemius, 15 – 18 hamstring, 19 , 20 infraspinatus, 21 and pectoralis minor 22 decreased immediately

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Filipe Conceição, Mark A. King, Maurice R. Yeadon, Martin G.C. Lewis, and Stephanie E. Forrester

This study aimed to determine whether subject-specific individual muscle models for the ankle plantar flexors could be obtained from single joint isometric and isovelocity maximum torque measurements in combination with a model of plantar flexion. Maximum plantar flexion torque measurements were taken on one subject at six knee angles spanning full flexion to full extension. A planar three-segment (foot, shank and thigh), two-muscle (soleus and gastrocnemius) model of plantar flexion was developed. Seven parameters per muscle were determined by minimizing a weighted root mean square difference (wRMSD) between the model output and the experimental torque data. Valid individual muscle models were obtained using experimental data from only two knee angles giving a wRMSD score of 16 N m, with values ranging from 11 to 17 N m for each of the six knee angles. The robustness of the methodology was confirmed through repeating the optimization with perturbed experimental torques (±20%) and segment lengths (±10%) resulting in wRMSD scores of between 13 and 20 N m. Hence, good representations of maximum torque can be achieved from subject-specific individual muscle models determined from single joint maximum torque measurements. The proposed methodology could be applied to muscle-driven models of human movement with the potential to improve their validity.

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Tetsuro Muraoka, Tadashi Muramatsu, Daisuke Takeshita, Hiroaki Kanehisa, and Tetsuo Fukunaga

This study estimated the passive ankle joint moment during standing and walking initiation and its contribution to total ankle joint moment during that time. The decrement of passive joint moment due to muscle fascicle shortening upon contraction was taken into account. Muscle fascicle length in the medial gastrocnemius, which was assumed to represent muscle fascicle length in plantarflexors, was measured using ultrasonography during standing, walking initiation, and cyclical slow passive ankle joint motion. Total ankle joint moment during standing and walking initiation was calculated from ground reaction forces and joint kinematics. Passive ankle joint moment during the cyclical ankle joint motion was measured via a dynamometer. Passive ankle joint moment during standing and at the time (Tp) when the MG muscle-tendon complex length was longest in the stance phase during walking initiation were 2.3 and 5.4 Nm, respectively. The muscle fascicle shortened by 2.9 mm during standing compared with the length at rest, which decreased the contribution of passive joint moment from 19.9% to 17.4%. The muscle fascicle shortened by 4.3 mm at Tp compared with the length at rest, which decreased the contribution of passive joint moment from 8.0% to 5.8%. These findings suggest that (a) passive ankle joint moment plays an important role during standing and walking initiation even in view of the decrement of passive joint moment due to muscle fascicle shortening upon muscle contraction, and (b) muscle fascicle shortening upon muscle contraction must be taken into account when estimating passive joint moment during movements.

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Kentaro Chino and Hideyuki Takahashi

independent of muscle mass. We previously assessed muscle stiffness of the medial gastrocnemius by shear wave elastography, and examined sex-related differences in the muscle stiffness and passive ankle joint stiffness. 8 Significantly greater ankle joint stiffness in men than in women was not found at 30