When one part of your body is in trouble – other parts have to come to the rescue: The game of Jiu jitsu is all about isolating one part of an opponents body and attacking it. Sometimes you will be on the wrong side of that methodology and find one part of your body has been isolated and about to be attacked. If you can react early enough then it's usually possible to simply pull the endangered limb free. However, if you're opponent is doing a good job of restricting your movement you'll need a more sophisticated approach. Rather than desperately try to extract your isolated limb – look to use other parts of your body to protect it. Here I am being effectively pinned in side control and my left arm has been isolated by an under hook. I react by wedging my right knee at the pocket of my opponents right hip and right forearm at the pocket of the left hip. This immediately restricts my opponents movement and makes it more difficult for him to transition into mount or move around to the other side of my body for upper body submission attacks. There is a sense in which I lost a battle on my left hand side and so I must win on the right hand side in order to prevent further loss. Once this barrier of elbow and knee on the right side has been established, any movement by my opponent will create sufficient space to join knee and elbow together as a locked frame and out the opponent back in guard where the isolated left arm won't be any use. next time your stuck and and arm or leg isolated – use this line of thinking to first protect yourself and then work safely out of the position and back on the attack!
