Kevin Blok is showing how to grab your training partner's hand when performing kotegaeshi nage, a popular martial arts technique that is used across numerous Japanese martial systems.
<a href="//commons.wikimedia.org/wiki/User:ZEDD,_JAMES_A_P" title="User:ZEDD, JAMES A P">ZEDD, JAMES A P</a>
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<span class="int-own-work" lang="en">Own work</span>