A well timed spin hook kick can be devastating; as you can see in the Heavy Weight final of the 2004 Olympic Games:
Moon Dae Sung 2004 Olympic Final
The video is 7 minutes long, but "ends" at around 3 1/2 minutes.
Spin Hook kick can be used much the same way as Back Kick, a trapping technique or a straight counter. Here are some examples:
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Some of the clips are poor video quality, and look better in the Windows Media Format below. File size is about 3.5 meg.
Windows Media: Spin Hook Kick
Fight Clip 1: Kicker, Lesley Edquid, AAU Regional, 2004
Fight Clip 2: Kicker, me, MA States, 1998
Fight Clip 3: Kicker, Todd Sayles, Quebec Cup, 2003
Fight Clip 4: Kicker, me, Goodwill Games Canada, 1995
Fight Clip 5: Kicker, me, New England Open, 1994
Fight Clip 6: Kicker, me, CT. Classic, 1996
I find teaching Spin Hook kick a challenge. Students often bring the body around first, and follow with the kicking leg, this turns the kick into a Spin Crescent rather then hook. Another common mistake is arching the back, which typically comes from attempting to spot the target, this prohibits the leg from following through and limits the height of the kick.