Junny Lock

What This Is

The Junny lock is an inside heel hook variant that uses a wrist and forearm wrap configuration rather than the standard palm-to-palm grip. The wrap creates a different lever geometry — the forearm applies rotational force to the knee through a mechanical advantage that differs from the standard inside heel hook finish. The target is the same: medial knee ligament structures, including the MCL and ACL, loaded through internal rotation of the tibia relative to the femur.

The technique sits within the inside heel hook family, but its platform is unlike any other member of it: the Junny lock is an inside heel hook hit without any ashi control of your own. It is a counter — a way of attacking the opponent’s reaping leg while they are reaping you. The knee-line control that an inside heel hook normally demands from cross ashi or 50/50 is supplied here by the opponent themselves: their reap threads their leg around yours, and that self-trapping fixes their tibia on the attackable line. The forearm wrap is what cashes it in, reaching the heel in a relationship where no palm-to-palm grip could be built. It is also found under the name “inverted heel hook variant” in some instructional contexts, though this description is imprecise and can refer to other techniques.

Because the Junny lock targets the same knee structures as the inside heel hook — and does so quickly — it carries the same injury risk profile. The page leads with defence. Understand what is being done before learning to do it.

Safety First

Training context. Not appropriate — elevated risk, inside heel hook restrictions apply.

The Invariant in Action

The Junny lock is available precisely when the opponent is reaping you. No ashi control of your own is established — bending down to build one would be slower than the attack itself. The reaping leg cannot be pulled free without the opponent first releasing their own entanglement, which is the defensive tell to watch for: while the reap stays committed, the leg stays trapped, and the trap is theirs.

The Junny lock’s forearm wrap changes the grip but not the mechanical truth: the heel is the handle and the knee is the target. The forearm provides the rotating lever — wrapping under the heel and rotating the forearm drives tibial rotation through the knee joint. A practitioner who focuses on pulling the foot rather than rotating through the knee will produce discomfort without submission threat. The rotational direction (internal — toward the attacker’s body) is identical to the standard inside heel hook.

Before the forearm wrap can be applied, the heel must be exposed — and in the Junny lock it is the reap that exposes it. Threading the leg around the attacker’s turns the reaping heel onto the inside angle. The wrap is applied to an already-exposed heel; it does not create the exposure. A reap kept shallow, foot hidden behind the attacker’s hip, presents no calcaneus to the ulna and the attack has nothing to close on.

Limb isolation is what makes any heel hook variant completable, and in the Junny lock the opponent provides it. A committed reap is a leg spent on entangling — tied to the attacker’s leg, away from its own core, unsupported by its partner. The forearm wrap works because the reaping leg has nothing left to defend itself with while it stays committed.

The reap provides the fixed point in the Junny lock. The opponent tied their tibia to the attacker’s leg; the forearm rotates the heel around that anchor and the torque lands on their knee. Nothing about the anchor is the attacker’s to maintain — and nothing about it is the attacker’s to lose. Only the reaper can dissolve it, by releasing the entanglement, and until they do the leverage mechanism is intact.

The forearm wrap places the ulna against the calcaneus at a different angle than the palm-to-palm IHH grip. This changes the direction of rotational force applied to the knee — the lever arm is the forearm bone, and the contact point is more distal on the heel. The result is that the same medial knee structures are loaded but via a different rotational path. If the forearm migrates to the calf or the ulna loses its purchase on the heel, the angle changes and the rotation no longer loads the knee efficiently. explains why forearm position is not interchangeable with a grip adjustment: the change is a force angle change.

Defence and Escape

We cover defence before attack. Understanding what is being done to you is the prerequisite for using this technique responsibly.

The escape principles

The Junny lock is defended from inside your own reap — you are the entangling player, and the attack lands on the leg you are reaping with. The defence principles are heel management and, above all, reap management: the attack only exists while your reap is committed, because your own entanglement is what traps the attacked leg. The normal cue “they are gripping my heel” may not be present — the forearm wrap approaches where no standard grip could. The attacker’s forearm under your reaping heel is the cue. Respond to the forearm contact, not to a completed grip.

Escape from the Junny lock

Manage the reap depth: The reap is your attack, and it is also the exposure. A reap kept with the foot tucked behind the opponent’s hip presents no heel to the forearm wrap; a lazy, over-rotated reap serves the calcaneus to the ulna. Reap with the heel hidden, or release and re-pummel rather than leaving a spent reap hanging on their leg.

Hide the heel before the forearm is placed: The heel exposure is the prerequisite. Turning the knee inward hides the heel from the inside angle that the forearm wrap requires. This is the first and most effective defensive movement and must happen before any wrap contact is established.

Prevent the forearm from getting under the heel: The attacker is bending toward your reaping foot to feed their forearm under the heel. Using the free leg to push the attacking arm away before the wrap closes is the escape window. This is the same principle as grip fighting in the standard inside heel hook — the fight is won before the wrap, not after it.

Release the reap: The anchor the submission rotates around is your own entanglement — the reaping leg tied to theirs (rotation around a fixed point). Releasing the reap dissolves the anchor: the leg comes free and the wrap has nothing to rotate against. This is the highest-percentage active escape, and it must be chosen early — a reap released after the elbow drive begins is a reap released too late.

Do not straighten the leg: Straightening the knee into the wrap applies more rotational force to the ligaments. The counter-intuitive response — bringing the heel toward the body — reduces the wrap’s mechanical advantage. Do not fight the rotation by extending; fight it by reducing the lever arm.

What causes escapes to fail

Escapes fail when the defender waits for pain to signal that they should react. The Junny lock applies rotational force before acute pain registers. A defender who responds to pain rather than to forearm-under-heel contact will tap during or after the damage. The escape requires a positional cue, not a pain cue.

Counter-offensive options

The primary counter from an active defence is to release the reap, recover the leg, and re-pummel into a fresh entanglement or seated guard — the attacker has bent down over your legs to make the wrap, and their posture is spent on it. A defender who disrupts the wrap arm early can also convert the attacker’s forward bend into a sweep entry.

Setup and Entry

Against the reap — the platform

The entry exists when the opponent is reaping you: standing or kneeling inside their leg entanglement, their leg threaded around yours. Their reap fixes their tibia line and turns their inside heel toward you — the two things an inside heel hook needs, both supplied by them. The attacker bends toward the reaping foot and places the near forearm under the heel — specifically under the calcaneus, with the forearm bone (ulna) acting as the pressure surface. The near arm comes from below; the far arm comes over the top or grips the near wrist to close the wrap. The rotation is initiated by driving the near elbow toward the mat while the reap is still committed.

Timing — attack the committed reap

The window is the opponent’s commitment. A reap in progress is a leg spent on entangling — it cannot defend itself until it is released, and releasing costs the opponent their entry. The attacker reads the depth of the reap: deep and committed means the heel is served; shallow and probing means the target is not yet there. Attacking a tentative reap wastes the bend — the leg simply withdraws.

Recognition, not construction

The Junny lock is not built the way an ashi entry is built. There is no entanglement of your own to establish, no inside space to win — the skill is recognising in real time that the opponent’s reap has trapped their own leg, and cashing the recognition in before they resolve the entanglement into their attacking position. This makes it an advanced tool: the recognition must be trained deliberately, because nothing about the position announces itself as an attack.

The Mechanics

The Junny lock’s distinguishing mechanical feature is the forearm wrap and the rotational direction it creates:

Forearm placement: The near forearm is placed under the heel with the ulna (inner forearm bone) contacting the calcaneus. The elbow points downward; the forearm is roughly vertical when the wrap begins. This is a fundamentally different contact surface than the palm-to-palm grip’s cupped hand configuration.

Wrap closure: The far arm comes over the top of the near forearm and connects — either gripping the near wrist, the near sleeve equivalent area, or making forearm-to-forearm contact. The wrap closes around the heel with the near forearm as the primary lever surface.

Rotation direction: The near elbow drives toward the mat while the attacker maintains their body connection. This drives the forearm into internal rotation — the heel is pushed inward (toward the attacker’s body) while the knee is pushed outward. This is the same medial knee loading as the standard inside heel hook: MCL and ACL structures are loaded through internal tibial rotation.

Why the geometry differs: The forearm wrap creates a longer lever arm between the contact surface and the attacker’s elbow than the palm-to-palm grip. This can generate rotational force with less arm movement — the wrap produces rotation through elbow drive rather than wrist pull. This is both the technique’s advantage (can apply force where palm-to-palm grip cannot) and its additional risk factor (the force profile is less modulated than a grip-based finish).

Position Requirements

• Standing vs Entangled Guard — The platform. The opponent is reaping you; their entanglement supplies the knee-line control and the heel exposure. No ashi of your own is involved.
• A committed reap — The condition, not a position. The attack exists only while the opponent’s reaping leg is spent on entangling yours; a released reap dissolves both the anchor and the window.

Common Errors

Drilling Notes

Ecological approach

Game: one player stands inside the other’s open guard; the bottom player’s task is to complete a reap entry to their entanglement. The standing player’s task: catch the reaping heel with the forearm wrap (Junny lock) before the entanglement resolves. Bottom player’s counter-constraint: reap with the heel hidden, or release and re-pummel when the wrap threatens. Neither player is told the wrap details — the attacker discovers the calcaneus placement through the constraint of a heel that is actively managed. Run for 30 seconds per round.

Systematic approach

Phase 1 (cooperative): partner holds a static committed reap on your lead leg; drill the forearm placement under their reaping heel. Focus only on placing the forearm correctly — calcaneus on the ulna — without closing the wrap. Ten repetitions each side. Checkpoint: is the contact point the heel bone, not the calf? Phase 2 (close the wrap, no rotation): close the far arm wrap without applying rotation. Confirm the wrap geometry before adding force. Checkpoint: does the wrap feel like a lever, not a squeeze? Phase 3 (full sequence, slow): reap recognition → forearm placement → wrap closure → elbow drive, with your own leg left where the reap holds it. Apply at 20% force only. The drill is about the mechanics, not the finish. Phase 4 (live with active defence): partner reaps with intent; attacker attempts the catch; the reaper hides the heel or bails out of the reap.

Ability level notes for drilling

Advanced: the Junny lock is an advanced technique. Foundations and developing practitioners should first develop the standard inside heel hook from cross ashi before approaching the counter version. Reading a reap well enough to attack it presupposes knowing the reap from both sides — applying the wrap without that foundation risks misapplying force at the wrong contact point on a moving leg.

Ability Level Guidance

Ruleset Context

The Junny lock attacks the same structures as the inside heel hook and is restricted identically. In IBJJF No-Gi, inside heel hooks have been legal for adult brown and black belts since 2021 and remain illegal below that, in all masters divisions, and in the gi; the Junny lock falls within that restriction. In ADCC and submission-only formats, it is legal. Always verify the specific ruleset before competing.

Also Known As

Related Pages