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. 2020 Feb 15;60(2):101-106.
doi: 10.2176/nmc.oa.2019-0206. Epub 2019 Dec 21.

Biomechanical Analysis of the Head Movements of a Person Thrown by the Judo Technique 'Seoi-nage'

Haruo Murayama  1 , Masahito Hitosugi  2 , Yasuki Motozawa  3 , Masahiro Ogino  4 , Katsuhiro Koyama  5
Affiliations

Biomechanical Analysis of the Head Movements of a Person Thrown by the Judo Technique 'Seoi-nage'

Haruo Murayama et al. Neurol Med Chir (Tokyo). .

Abstract

The present study examined the kinematics and biomechanical parameters of the head of a person thrown forward by the judo technique 'Seoi-nage'. A judo expert threw an anthropomorphic test device (the POLAR dummy) five times. Kinematics data were obtained with a high-speed digital video camera. Linear and angular accelerations of the head were measured by accelerometers mounted at the center of gravity of the dummy's head. When Seoi-nage was performed, the dummy fell forward accompanied by contacting the anterior parietal regions of the head to the tatami, and the linear and angular accelerations of most axes reached peak values when the head contacted the tatami. Peak resultant linear and angular accelerations were 20.3 ± 9.8 G and 1890.1 ± 1151.9 rad/s2, respectively (means ± standard deviation). Peak values in linear and angular acceleration did not significantly differ between the three directional axes. Absolute angular accelerations in all axes observed in Seoi-nage were high and the resultant value was approximately equal to the already reported in Ouchi-gari, one of the predominant techniques causing judo-related acute subdural hematoma. However, the remarkable increase of linear acceleration in the longitudinal direction and/or angular acceleration in the sagittal plane, as previously reported in techniques being thrown backward (i.e., Ouchi-gari and Osoto-gari), was not detected. The likely mechanism of acute subdural hematoma caused by Seoi-nage is that a large angular acceleration causes large strains and deformations of the brain surface and subsequent rupture of cortical vessels.

Keywords: acute subdural hematoma; head acceleration; judo techniques; prevention.

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Conflict of interest statement

Conflicts of Interest Disclosure

All authors declare that they have no conflicts of interest. Masahiro Ogino is a member of the Japan Neurosurgical Society (JNS) and has registered online Self-reported COI Disclosure Statement Forms through the website for JNS members.

Figures

Fig. 1.
Fig. 1.
Images showing the Seoi-nage technique. The white figure is the Judo expert, while the black figure is the anthropomorphic test device.
Fig. 2.
Fig. 2.
Representative time courses for the linear (A) and angular (B) accelerations in each direction during Seoi-nage.
Fig. 3.
Fig. 3.
Peak absolute values of the linear (A) and angular (B) accelerations in each direction during Seoi-nage. *P <0.05, Steel-Dwass test.
See this image and copyright information in PMC

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