Achilles lock - Everything2.com

The achilles lock (aka achilles tendon lock) is arguably the most versatile of all joint lock attacks to the legs. There are setup and executions from almost every conceivable fighting and grappling situation. The achilles lock is unusual for a leg lock because it can be modified for use as a pain compliance joint lock without losing its efficacy for joint destruction. The basics of this lock are easy to absorb and safe to perform, thus lending itself easily to the novice's learning experience. The usage and variations of this particular lock outweigh other ankle locks by such a large margin that if someone refers to an ankle lock without specifying what kind, he is most likely refering to the achilles lock. The achilles lock takes its name from the amount of pressure placed on the achilles tendon during its execution.

Basic Mechanics

There are several major variations of the basic achilles lock, I will first describe features common to all or most before I describe the major variations. This lock works by by placing a fulcrum on the achilles tendon and pressure on the instep of the foot. If you are having trouble picturing this, point your toes as a dancer would. Now, instead of stopping at the limits of motion, picture your foot being forcibly further bent downward as torque is applied around the axis formed through your ankle bones. This is the basic mechanical action of all variations of the achilles lock.

For descriptive purposes, we will assume the foot being locked is the opponent's right foot. For the sake of clarity, this writeup will take an instructional point of view. Unless otherwise specified, we will assume the lock is taking place on the left side of your body. In this example, we will start with both parties seated, facing each other. Your opponent extends his right foot. His right leg is between your legs, extending over your left hip and eventually ending up under your left arm. Grasp his right foot with your entire arm. His instep should be flush against your armpit and your arm should competely encircle the leg right around the ankle joint. Your forearm should be directly underneath his achilles tendon. In this position, hole created between your left arm and your body should be small enough that the foot is secure. All major variations now involve leaning back while preventing the opponent from sitting up, preferably completely immobile. The straighter the locked leg (from hip to the ball of the foot), and the further down the leg (towards the toes) without compromising your grip, the more powerful the lock will be.

Grip

There are two major gripping variations for securing the foot underarm: The hand-to-hand grip and the figure-4 grip. People who have learned one variation first and have not learned the relative pros and cons of the other will often tell you that you're doing it the wrong way. This is wrong. Each grip has its advantages and weaknesses.

The hand to hand grip is just what it sounds like. There are a couple ways to do this variation. One is the standard palm to palm wrestling grip. While this is a strong grip, it turns the blade of the wrist away from the achilles tendon, taking away the major advantage that can come from this grip - using the blade of your wrist to dig into the achilles tendon, causing a sharper pain that with other grips. The other way to do a hand to hand grip is to make a fist with your left hand and using your right hand to support it. You can push from the bottom or pull from the top of the fist, whichever the situation dictates. Grappling and fighting are dynamic activities and your responses should change as the situation changes.
The figure four grip is performed in the following manner: The left wrist, palm facing your torso, grasps the right wrist, palm also facing your torso. The right hand is placed on the shin of the locked leg, directly above the ankle. Looking down at the grip, figure four aspect should quickly become obvious. This advantage of this grip is that it is more secure - the hand on the shin can be used to further secure the leg.

Leg placement

Trapping and holding the foot underam is only the first step in completing this technique. Locking the foot is useless without immobilizing the body. Allowing the body freedom of motion allows your opponent to easily counter your attack. In all of the following variations, its important to squeeze your legs.

Left foot on opponent's abdomen and right leg cocked with right foot flat on ground. This is the first placement that a beginner learns and while the simplest variation, is the easiest to counter.
Left foot thread over opponent's hip and placed under his buttocks. Right foot in crook of opponent's left knee. This placement spreads your opponent's legs and places you oblique to his body. This makes it hard for him sit up and effectively places your body further away from his. This also makes it harder for your opponent to stomp on your face if this is a situation where striking is a possibility (UFC or real fight).
More variations to be added

Basic Counters

As with all joint locks, resistance is futile once the lock is set and the pressure is on. The time to perform a counter is before the submission is set, not after.

All counters to the achilles lock involve two aspects: closing the distance between you and your opponent's hips and removing the immediate danger of injury to your foot. This is accomplished in a number of different ways, the following of which are a few:

If the lock is just starting to be executed, sit up and grab hold of your opponent's collar if he is wearing a gi, neck if he is not. If you are too far away, attempt to "scootch" in towards him. Push down with the heel, like you are putting on a boot. This removes the immediate threat.
Clear the foot on your hip or abdomen. Roll onto the side away from the lock. Bend your leg as far as possible at the knee. As you sit up while arching away, this action will give you enough room to play with to work on closing the distance.
More counters to be added

Common setups and variations

The achilles lock has too many scenarios and variations to list all of them here so only a few basic will be listed:

Following the breaking of your opponent's guard or after a takedown where both of you have gone to ground and you have ended up between your opponent's legs. This is the most common scenario and often ends in the "standard" achilles lock.
Following a caught and trapped kick. The kicker can be tripped and the standing achilles lock can be executed. From the standing achiles lock, if you step over his body, this becomes the pro-wrestlingesque half boston crab.
Following a caught and trapped kick. Drop to the ground as your left knee catches him behind his right knee. The right hand immobilizes the supporting leg. Use your backwards momentum and right foot behind his hip to sweep him off his forwards as you roll backwards. This results in a face down version.
From your back to a standing opponent. Your left arm traps his left foot. Your left thigh is behind his right knee and your left foot is planted on his right hip. Your right foot is behind his left knee and your right hand is immobilizing his left foot. Pushing with your left foot while pulling with your right hand will sweep him, from where the lock can be completely executed.

The achilles lock is considered a "straight" lock because the torque is being applied on the same axis as the major direction of movement of the joint. Because it is a straight lock, it is considered safe and is legal in most forms of grappling and fighting competitions that allow joint locks, with the notable exclusion of judo. An example of a twisting lock would be the heel hook which rotates the lower leg around the axis formed by the leg from hip to foot, perpidicular to the natural axis of motion for the knee.