Ukemi Technique Prevents the Elevation of Head Acceleration of a Person Thrown by the Judo Technique ‘Osoto-gari’
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- MURAYAMA Haruo
- Department of Health and Sports Sciences, Premedical Sciences, Dokkyo Medical University School of Medicine
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- HITOSUGI Masahito
- Department of Legal Medicine, Shiga University of Medical Science
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- MOTOZAWA Yasuki
- Department of Mechanical and Precision System, Teikyo University
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- OGINO Masahiro
- Department of Neurosurgery, Dokkyo Medical University School of Medicine
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- KOYAMA Katsuhiro
- Graduate School Department of Interdisciplinary Research, University of Yamanashi
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Abstract
<p>Biomechanical analysis was performed to evaluate the effectiveness of mastering ukemi in preventing severe head injury in judo. One judo expert (tori) threw another judo expert (uke) with a skilled break-fall (ukemi) four times. We obtained kinematic data of uke with a digital video camera. Both translational and rotational accelerations were measured with a six-degree-of-freedom sensor affixed to uke’s forehead. When Osoto-gari was performed, uke fell backward and his arm made contact with the tatami; the translational and rotational accelerations rose to peak values. The peak resultant translational and rotational accelerations were respectively 10.3 ± 1.6 G and 679.4 ± 173.6 rad/s2 (mean ± standard deviation). Furthermore, when comparing the values obtained for the judo experts with those obtained using an anthropomorphic test device (ATD: the POLAR dummy) that did not perform ukemi, both the peak resultant translational (P = 0.021) and rotational (P = 0.021) accelerations of uke were significantly lower than those for the ATD, whose head struck the tatami. Additionally, there was no significant difference among the three axis directions for either translational (ax: 7.4 ± 0.2, ay: 8.5 ± 2.1, az: 7.2 ± 0.8 G) or rotational (αx: 576.7 ± 132.7, αy: 401.0 ± 101.6, αz: 487.8 ± 66.6 rad/s2) acceleration. We confirmed that performing correct ukemi prevented the elevation of head acceleration by avoiding head contact with the tatami when a judoka is thrown by Osoto-gari. Judoka should therefore undertake intensive practice after they have acquired ukemi skills.</p>
Journal
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- Neurologia medico-chirurgica
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Neurologia medico-chirurgica 60 (6), 307-312, 2020
The Japan Neurosurgical Society