TV show Sportscience did a study on effectiveness of footlocks and armlocks using Frank Mir. We have this to say on the matter about what submission is more effective:

“Arm Locks

Going for his arm bar, the initial force is just 60 lbs. For what it’s worth, they also tell the viewer that Frank delivers close to HALF A TON OF FORCE on a punch! Sheesh. Anyway, the arm bar is enough to do damage, but when you factor in the high level grapplers that he faces can easily defend against it.

However, when Frank engages his hips the amount of force jumps stays at 60 lbs but given the torque added there is a brutal 150 newton meters being applied to the hold. This is far more than enough to snap a limb, just as Tim Sylvia who had his arm broken by Mir back at UFC 48.

Leg Locks

After Frank arm barred the dummy, he proceeded to knee bar it. Upon doing so, Frank snapped the leg right in half…the leg was being held together by a METAL ROD! What’s interesting is that Frank applied the same amount of force; 60 lbs.

However, he was able to exert 175 newton meters onto the joint, which is more than the arm bar despite the same force! The reason for this was because legs are longer than arms. When you attack the limb, since it’s longer it becomes more vulnerable to the pressure being applied. Also, with the arm bar, Frank has a very limited range of motion on the move.

The knee bar has a great range for Frank to work with, thus allowing him to add more and more pressure to the hold, causing the weak structure of the knee to crumble slowly.

So there you have it, the arm bar vs the leg lock! After looking at the information, it’s easy to see that the knee bar is the more devastating more of the two but lets be real…both really hurt!”