Kazuhiko Watanabe

Hiroshima University, Hirosima, Hiroshima, Japan

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Publications (4)3.66 Total impact

  • Yun Wang, Kazuhiko Watanabe, Tadayoshi Asaka, Fatao Wan
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    ABSTRACT: To study multi-muscle synergies during preparation in making a step (self-paced level stepping vs. obstacle crossing stepping).
    European journal of applied physiology. 08/2014;
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    ABSTRACT: [Purpose] This study investigated the characteristics of postural control following postural disturbance in elite athletes. [Subjects] Ten elite ski jumpers and ten control subjects participated in this study. [Methods] Subjects were required to maintain balance without stepping following unexpected horizontal surface perturbation in a forward or backward direction. [Results] A lower and reproducible peak magnitude of the center of mass velocity was shown in the athlete group compared to the control group. Cross-correlation analyses showed longer time lags at the moment of peak correlation coefficient between trunk flexor and extensor muscle activities, and shorter time lags and higher correlations between ankle flexor and extensor muscle activities were shown in the athlete group than in the control group. [Conclusion] The elite ski jumpers showed superior balance performance following surface perturbations, more reciprocal patterns in agonist-antagonist pairs of proximal postural muscles, and more co-contraction patterns in distal postural muscles during automatic postural responses than control individuals. This strategy may be useful in sports requiring effective balance recovery in environments with a dynamically changing surface, as well as in rehabilitation.
    Journal of Physical Therapy Science 06/2014; 26(6):833-9. · 0.18 Impact Factor
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    Yun Wang, Tadayoshi Asaka, Kazuhiko Watanabe
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    ABSTRACT: We studied multi-muscle synergies of healthy elderly persons during preparation to making a step (self-paced vs. reaction time). The uncontrolled manifold hypothesis was used to explore the organization of leg and trunk muscles into groups (M-modes) and co-variation of M-mode involvement (M-mode synergies) during stepping tasks. We hypothesized that aging accounts for changes in the structure of M-modes, as well as in M-mode synergies. Subjects performed two tasks: (1) a cyclic COP shift over a range corresponding to the maximal amplitude of voluntary COP shift at 1 Hz, (2) stepping tasks under 3 instructions, "comfortably, self-paced," "very quick, self-paced," and "as fast as possible to a visual signal." Electromyographic signals of 10 postural muscles were recorded and analyzed. Principal component analysis was used to identify M-modes within the space of integrated indices of muscle activity in the cyclic sway task. Variance in the M-mode space across stepping trials was partitioned into two components, one that did not affect the average value of COP shift and the other that did. An index (ΔV) corresponding to the normalized difference between two components of variance was computed. The elderly subjects showed more "co-contraction M-mode" and "mixed M-mode" than that of the young subjects. During stepping tasks, both subject groups showed M-mode synergies stabilizing COP shifts in the stepping and supporting legs. The synergies of elderly subjects showed a smaller and delayed value than that of the young subjects. These results suggest that aging is associated with diminished control in multi-muscle synergies in the anticipatory postural adjustments during gait initiation.
    Experimental Brain Research 04/2013; · 2.22 Impact Factor
  • Yun Wang, Kazuhiko Watanabe
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    ABSTRACT: The notion of limb dominance has been commonly used in the upper extremity, yet the two lower extremities are often treated as equal for analytical purposes. Attempts to determine the effects of limb laterality on gait have produced conflicting results. The purpose of this study was to determine if limb dominance affects the vertical ground reaction force and center of pressure (COP) during able-bodied gait. The Parotec system (Paromed GmbH, Germany) was used to collect plantar foot pressure data. Fifteen subjects volunteered to participate in this study. The coefficient of variation of the COP displacement in the mediolateral direction and the variability of peak force beneath the lateral forefoot in the nondominant foot were significant greater than in the dominant foot. Moreover, COP velocity in the anterior-posterior direction during the terminal stance phase showed greater value in the dominant foot. Our study provides support for limb laterality by showing limb dominance affected the vertical ground reaction force and center of pressure during walking gait. This finding suggests it is an important issue in movement science for clinicians and would assist in improving sports performance and rehabilitation program.
    Journal of applied biomechanics 08/2012; 28(4):473-8. · 1.26 Impact Factor

Publication Stats

5 Citations
3.66 Total Impact Points

Institutions

  • 2014
    • Hiroshima University
      • Center for Collaborative Research & Community Cooperation
      Hirosima, Hiroshima, Japan
  • 2013
    • Tianjin University of Sport
      T’ien-ching-shih, Tianjin Shi, China