Journal of the Society of Biomechanisms
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Volume 44, Issue 3
Displaying 1-12 of 12 articles from this issue
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Paper
  • Estimation of Body Segment Densities for Japanese Athletes from Magnetic Resonance Imaging
    Hidetaka OKADA, Toshiharu YOKOZAWA, Hideyuki TAKAHASHI
    2020 Volume 44 Issue 3 Pages 162-170
    Published: 2020
    Released on J-STAGE: August 27, 2020
    DOIhttps://doi.org/10.3951/sobim.44.3_162
    JOURNAL FREE ACCESS
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    The purpose of this study was to estimate the body segment density from one MRI image for each body segment by continuously acquiring cross-sectional images of Japanese male and female athletes using MRI. First, a preliminary analysis was conducted for six male and female athletes to determine the range of appropriate cross section selection for estimating the body segment density. Next, we used 21 other male and female athletes as subjects and estimated the body segment density from one MRI image for each body segment. As a result of the preliminary analysis, it was suggested that analysis of one MRI image for each body segment gave the similar value of body segment density as in analyzing many successive MRI images. Moreover, the sex difference in body segment densities between the male and female athletes and the difference in body segment densities between the athletes and the cadaver specimens (Caucasian middleaged or aged males) were clarified.
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  • Effect of the Chronic Ankle Instability on the Function of the Foot during Lateral Jump Immediately After Single Leg Landing
    Takaya WATABE, Tomoya TAKABAYASHI, Masayoshi KUBO
    2020 Volume 44 Issue 3 Pages 171-178
    Published: 2020
    Released on J-STAGE: August 27, 2020
    DOIhttps://doi.org/10.3951/sobim.44.3_171
    JOURNAL FREE ACCESS
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    The purpose of this study was to investigate the effect of the chronic ankle instability (CAI) on the function of the foot during lateral jump immediately after single leg landing. Using the Cumberland Ankle Instability Tool, 16 subjects were separated into the 8 healthy control group (age = 20.8±0.8 years, height = 171.8±4.5 cm, mass = 61.0±5.4 kg) and 8 patients of CAI group (age = 20.1±0.8 years, height = 173.8±7.1 cm, mass = 62.3±8.2 kg). The task was the landing with right leg on the board from the platform with 20 cm in height. The board was designed to tilt either in left or right by 8 degrees or 0 degrees, at the moment of landing. The subjects were instructed to perform the lateral jump within a second in the direction of the tilt or the forward jump if there was no tilt. There were no significant differences between the two groups in the performance time（ from initial contact to toe off） of the jump and in the direction of the force vector applied to the board. However, CAI group significantly increased in the peak value of the ankle varus angle, delayed the reaction time of the peroneus longus muscle, and increased the number of mistakes in the jumping direction, when the board was tilted to the right. We concluded that, in the case of dynamic tasks that require the quick judgment of ankle inclination, the presence of CAI would result in the occurrence of disagreement between required and intended movements. For the purpose of re-injury prevention, examination, and training of proprioception of ankle joint in dynamic condition may be recommended.
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  • Difference of lower limb control by foot strike pattern during walking on irregular surface
    Kenta Igarashi, Hiroshi Yamada, Koichi Koganezawa
    2020 Volume 44 Issue 3 Pages 179-186
    Published: 2020
    Released on J-STAGE: August 27, 2020
    DOIhttps://doi.org/10.3951/sobim.44.3_179
    JOURNAL FREE ACCESS
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    The research aims to thoroughly examine a normal person’s strategy for walking on irregular surfaces, especially under unforeseeable conditions. Seven subjects walked on a flat path partly paved with irregular surface that was arranged by lining up lumps; semicircular cross-sectional rods (2 cm diameter) in equal distance (75% of Foot length). The irregular zone was covered by a cloth so that the subjects did not recognize the zone. Kinematic data were collected at 100 Hz by using the motion analysis system with ten cameras, and simultaneously electro-myography (EMG) data were collected at 1000 Hz by surface electrodes. Three walking conditions were tested: (1) foot stepping on a single lump (SLC), (2) foot stepping on double lumps (DLC), (3) foot stepping on flat surface (NLC). We examined angle trajectory and torque variation of hip, knee and ankle joints during one step separated by double legs support phase (DSP), first half single leg support phase (SSP1) and the second half one (SSP2). On irregular surface walking, high co-contraction of ankle joint mainly due to reflective activation of gastrocnemius muscle (GA) during DSP induces the torque of knee extension from DSP to SSP1. During DSP, the co-contraction of knee joint becomes lower in SLC than in DLC. On the other hand, the co-contraction of ankle joint becomes higher in DLC than in SLC. As a result, we found that the subjects walked on irregular surface under narrow stability margin.
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Short Paper
  • A Prototype of Prosthetic Sport Foot for Long Jump
    Kazunori HASE, Hiroto TOGAWA, Satoshi KOBAYASHI, Goro OBINATA
    2020 Volume 44 Issue 3 Pages 187-190
    Published: 2020
    Released on J-STAGE: August 27, 2020
    DOIhttps://doi.org/10.3951/sobim.44.3_187
    JOURNAL FREE ACCESS
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    The purpose of this study is to develop a prototype of prosthetic sport foot for amputee long jump based on our simultaneous optimization simulation of both prosthesis shape and takeoff action. Elastic property of the prosthetic foot was modeled by the flat spring design formulas. The simultaneous optimization results demonstrated a straight shape at the end part of the prosthetic foot and a takeoff motion achieved a jump distance of over 7 m. Two-dimensional design drawings were drawn from the optimized design parameters such as arc lengths and curvatures of the arc elements of the prosthetic foot shape. Moreover, nonlinear elastic properties were quantified by a virtual elasticity test in a computer in which the mechanical relationship between the external load and flexibility at the tip of the prosthetic foot was investigated two-dimensionally. We asked a specialized company to select prepreg materials and to design the laminates according to the above information. We also asked them to produce a prototype of the prosthetic foot made with carbon fiber reinforced plastic (CFRP). The proposed prosthetic foot will be evaluated by the target amputee athlete in the future.
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