If you can isolate an arm – you can break an arm: arm locking an opponent who knows what an arm lock is and how to defend it never an easy thing. One way to make things easier is to on isolating one arm from the other. The principle of double trouble runs throughout Jiu Jitsu. NINETY PERCENT OF THE RESISTANCE TO A GIVEN JOINT LOCK ON AN ARM OR LEG COMES FROM THE OTHER ARM OR LEG. So if you can the defensive effects of the OTHER limb, breaking a limb becomes a LOT easier. There are many ways to isolate one limb from the other. In the case of one of the most popular and effective arm locks – Kimura – one highly effective method is to lock a triangle (sankaku) around your opponent’s head and arm and then upon the isolated and vulnerable trapped arm within the triangle. It is now significantly harder for your opponent to engage his other arm defensively. In addition, the head control greatly amplifies the breaking power of the Kimura by reducing the defensive head movements that can undermine the effectiveness of the Kimura lock. Here, outstanding junior uses triangle and Kimura in unison to do exactly this – the result is a punishing Kimura lock that is very difficult to defend and in the few cases where a successful defense can be made, leads immediately into other submission possibilities.