The 3 Joint Rule is the key to effective arm drags, leg drags, and jointlocks.
Arms and legs contain three major joints.
- In the case of arms: the wrist, elbow, and shoulder.
- In the case of legs: the ankle, knee, and hip.
The human body is extremely adaptable, thanks to our three-jointed limbs. If an opponent has ever escaped your single leg by hopping all over the mat, you’ve experienced this firsthand.
This adaptability makes it pretty hard to control someone by grabbing their limb. Even if you can immobilize one joint, the pressure can “bleed” into the adjacent joints, allowing your opponent to bend and escape.
That’s where the 3 Joint Rule comes in.
If you want to control a limb, you need to control at least 2 of the 3 joints.  For example, if you want to arm drag someone, you need to control their wrist and their elbow. You won’t succeed with wrist control alone. This is why Aikido throws don’t work against a resisting opponent.
A submission requires control of all 3 joints in the limb.  If your opponent is wiggling or rotating out of your submissions, this usually means you’re not controlling all 3 joints.
Summary of the 3 Joint Rule:
- For arm/leg control, you need to control 2/3 joints.
- For arm/leg submissions, you need to control 3/3 joints.
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Upgrade your armbar with the 3 Joint Rule
Let’s give a very specific example of the 3 Joint Rule in action: the armbar.
Finishing the armbar is a lot more nuanced than grabbing the hand and leaning back. Like any submission, the hard part is keeping your opponent immobilized so they can’t escape.
With the armbar, the main escapes you’ll likely see are:
- the bridge escape, where your opponent bridges into you and stacks you
- the hitchhiker escape, where your opponent rotates their body so the arm can bend at a natural angle.
In both of these scenarios, your opponent was able to escape because you failed to immobilize the shoulder.
This is an example of the 3 Joint Rule in action: you had control of the wrist and elbow, but because the shoulder was not immobilized, your opponent was able to either turn toward you (the bridge escape) or turn away from you (the hitchhiker escape). To prevent your opponent from escaping the armbar, you need to immobilize all three joints.
So how do you do it? Immobilizing the shoulder is tricky.  The easiest way to immobilize the near shoulder is to restrict movement on the far side. So in the case of the armbar, this means wedging in tight against the far shoulder. You normally do this by pinching or crossing your ankles, but you can also reach over and use your hands to grab the far tricep if you know what you’re doing.
Controlling the far shoulder prevents your opponent from rotating their body, which means the shoulder you’re actually attacking is immobilized. If you have a good pinch on the far shoulder you’ll find your opponents have a much harder time escaping your armbar.
If you ever get that feeling that your armbar is loose and your opponent may escape, switch your focus to wedging in the far shoulder.
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