Chain wrestling, transition, or whatever you call it - it is a technique that one uses to attempt to continue wrestling (I say "wrestling" because I learned this training technique initially in wrestling) if your opponent attempts to counter you.
In wrestling two people would go half speed from move to move countering eachother.
One key point to keep in mind when practicing with "chains" or "transitions," as was intelligently alluded to by mrymz, is not to get caught up in patterns. You don't want to become predictable by conditioning yourself to respond the same way all the time in a given situation.
The scenario one wants to aspire to is to transition from one move to another seamlessly, but not to a predetermined counter to your opponent's move. You want to transition to the "best" counter based on the situation you are in.
This level of skill is attained by long periods of chain wrestling with a partner that will put you in the same situation many times so that you can transition to various situations by executing different counters.
After several sessions of chain wrestling, the counters will start to come naturally; and you will find yourself flowing into the appropriate counter when going full speed in practice, or in an actual match. And you will be fully prepared if your opponent has an effective counter for your counter.
One last point: When I say "half speed," that doesn't necessarily refer to the actual speed or tempo (though it can when slowing down to get the feel of a move). It refers to the intensity of the action. You are not trying to actually counter your partner in a practice section of chain wrestling. You want to employ a good counter and then respond with another after he does the same thing.
You simply continue for a set period of time.
Hope this helps,
Ultimate Fighting Championship MMA news on UFC Tickets, Events, Gear, Clothing, and more.