I'd always taken for granted everyone thought that checking was (ideally) using the harder/higher part of your own shin, to block your opponents kick on their weaker/lower shin. Or even better foot and instep.
Actually no. I always thought just shin on shin.
The rest I learned later.
As my Sifu describes it: In a violant wind storm such as a Tornado the willow tree will often survive where the Oak will break. One is very strong but stiff and rigid. It will absorb a lot of punishment without moving but once it reaches a certain stress point it will crack. A Willow tree while not being as "strong" as an Oak will have enough flexibility to move with the wind and survive. Be the Willow.
Your taking just enough weight off the leg that it moves with the kick enough to absorb a significant percentage of the impact. It's a comprimise between stepping out of range and just taking the blow.
This is such a fundamental lesson that there is an actual willow and oak planted by the students in the back of the school.
The problem with using a metafor like that is that is can be interperated a few different ways. Some of them right. Some of them wrong.
If you bend during a kick battle you will keep bending.
that MMA vs krotty spar is a good example of that. As soon as the guy gets hit his composure gets broken and he is unable to defend or attack.
I didn't see anything in your style field, so am unsure what you mean by "karate sparring", but the blocking of an incoming kick by raising your leg and "checking" the incoming kick is how I hear that term the most often. This is legal in "most" karate tournaments and is used regularly in the gym.
Originally Posted by SeroX
We also use that term to a lesser extent to refer to the practice of "checking" our opponent's front leg by shin kicking it (most typically with your front leg), then following up with other attacks, usually crosses (reverse punch to some karate folks). This is legal in many fewer karate tournaments; they usually don't allow anything more violent below the belt than a boot-to-boot foot sweep, it that.
As always, ask your instructor(s) for some clarification.