This is article is from Fights Gone By and continues there. http://fightsgoneby.blogspot.com/
Hand trapping is the act of slapping, pulling or pressing one or both of an opponent's hands out of the way in order to fire a strike through the hole created. Hand trapping can be as simple as slapping someone's hand down and hurling an overhand, or can be a more complex and pressuring art form. Many forms of martial art focus largely on the many variations of hand trapping; Wing Chun and Kali being the main ones, but it exists in Karate, Boxing, Kickboxing, Muay Thai and just about any art form where free sparring is used. Many who watched the UFC match between Overeem and Lesnar will have noticed that Lesnar seemed almost helpless as Overeem stepped forwards toward him - largely due to Alistair's hand fighting. Lesnar (whose shakiness under fire is well known) had clearly been told to keep his hands up by his team and so was reluctant to fire punches, Overeem meanwhile stepped forward, covering the bigger mans hands and eliminating Lesnar's ability to punch while he stepped in to throw is infamous Uberknee. This is an advanced level of hand fighting, and one you will likely only see used by great strikers against less-than-stellar strikers, but many variations on hand trapping exist.
Hozumi Hasegawa vs Gerardo Martinez (via dontoman)
In this clip Japanese boxing phenomenon Hozumi Hasegawa comes out to start the 7th round and immediately drops Gerardo Martinez on the seat of his trunks. If you rewind to 0:05 it becomes clear how Hasegawa managed to drop his opponent with such a basic punch immediately on leaving his own corner. Hasegawa has fought six rounds prior to this in which he, as a southpaw, has been using his right hand to slap down, push around and annoy his opponent's leading, left hand. Immediately after slapping down his opponent's hand he has often used the path opened to throw a right handed jab straight back along his opponent's arm. Though it is not a damaging punch it has clearly begun to annoy Martinez as when Hasegawa does it again at 0:05 in this video, Martinez instinctively snaps his lead hand back up to cover, leaving the hole needed for the left straight which Hasegawa has already thrown in anticipation of Martinez's reaction. The result is that Martinez's lead hand flies up, exposing his chin and Hasegawa powers a fine looking left straight down the pipe, from which Martinez never recovers and goes on to be TKO'd later in the round.
Fedor Emelianenko vs Antonio Rodrigo Nogueira - III (via MrDavidDux)
Another type of handtrap is demonstrated by Fedor Emelianenko (who is going to come up again in this article) against Antonio Rodrigo Nogueira in their third meeting here. At 15:49 Fedor uses his lead left hand to slap Nogueira's lead left hand outwards and throw an overhand (more accurately termed a "casting punch" by sambo pracitioners) down the middle. This would normally eliminate Nogueira's ability to check the punch, but as Nogueira attempts to kick at the same time, he has the misfortune of running onto the full force of it. At 16:38 you can see what Fedor meant to do without Nogueira running on to his punch as he slaps the Brazilian's hand aside again and throws his overhand down the pipe with frightening accuracy. Nogueira's brilliant chin and heart hold him up where his boxing technique does not however, and he survives the 3 rounds in one of the best heavyweight contests in MMA history. The big hand trap to punches are repeated in slow motion at 21:15 and 21:31.
A third, more advanced form of hand trap is performed with the rear hand, then the lead hand is used to throw a power punch. Most will be familiar with George Foreman and his winning of the heavyweight boxing title for a second time at the age of 45; an interesting note is that for his comeback George hired Archie Moore "The Old Mongoose" to act as his trainer, meaning that his boxing technique and tricks were greater at the age of 45 than they had been when he was in his physical prime. At 7:12 George swings a looping right hand trap downwards, in order to slap down Cooney's lead hand and follows it with a left uppercut that connects. At 7:15 George Foreman comes out of a combination using his rear hand to smother Cooney's famous left hook preemptively, and delivers a hard jab with his left hand, following up with a right hand and a combination on the stunned Cooney, dropping him.
George Foreman vs. Gerry Cooney 15th Jan 1990 (via flashingswords)
This article is from Fights Gone By and continues there to discuss Fedor Emelianenko's "Zulu" technique.