The most important space on your body that nobody bothered to name.

I have spent over thirty five years being corrected, and most of those years, giving the same correction out.

“Elbows in.”

It came from my karate instructor when my punch drifted wide. From my judo coach when my grip broke and my arm floated away from my body. It comes out of my own mouth three or four times a night at my academy HQ in Bedford, usually to somebody halfway through losing an arm they did not know they had lent out.

Three arts. Three generations of teachers who never met. The same two words: “elbows in”.

Waki no shita

The Japanese for the armpit is waki no shita. Waki is the side or the flank. Shita is under. Put them together and you have the underarm, nothing more mystical than that.

There is enough invented tradition in martial arts already, so let me be upfront. Wakinoshita is not a lost koryū principle. It is not a secret scroll teaching. It is a word you would use to describe where you put your deodorant.

I first heard it said out loud in Seattle, in 1999. I was part of a small UK contingent training at the Minakami Karate Dojo, and we were well into one of Minakami Shihan’s more exhaustive sessions when he stopped the floor to tell me my wakinoshita was open. I nodded “Ossu Shihan” as though that meant something to me – it did not.

What happened next is why this article exists. Instead of giving me a correction and moving on, he gave me the history. Where the word came from, what old Samurai armour did about it, why every art he had trained arrived at the same instruction by a different road. Ten minutes standing still in a soaked gi, going cold. I have been chewing on it ever since.

The armourer’s problem

Samurai armour left a gap between the torso and the arm – it had to. Seal it completely and the wearer cannot lift a sword, draw a bow, or turn in the saddle. The opening was the price of movement and accessibility.

The trouble is that a thrust into that gap misses the ribcage entirely and arrives at the lungs and heart. Innovative armourers answered with the wakibiki, panels of mail or small plate hung from the shoulder and suspended over the underarm, worn inside or outside the chest armour.

One group spent centuries trying to close the armpit, whilst another spent the same centuries trying to get into it. The opening is not a design flaw, it is the cost of being able to move at all – hold that thought, it’s the whole article.

What the closed armpit is actually for

Watch a Shotokan karateka throw choku zuki. The withdrawing hand, the hikite, comes back to the hip with the elbow tight to the ribs. The punching arm extends with the elbow down, not flared. Both armpits stay shut. Beginners assume this is aesthetic, a hangover from an older way of doing things. It is not.

And before anyone files it under nostalgia, the arts with no tradition to protect are just as strict. Walk into a boxing gym and count the seconds before a coach barks at a drifting elbow. Nobody there is preserving a lineage, they are preserving a fighter. A flared elbow uncovers the ribs and the flank, and what waits in that gap is the body shot. The liver shot does not knock a man out so much as switch him off. He stays conscious. He simply cannot stand. No scrolls, no kata, just consequence.

The reason is identical in both rooms. A closed armpit connects the arm to the trunk. The shoulder girdle sits on the ribcage, the ribcage on the hips, and the hips are where the power lives. Shut the underarm and the arm inherits everything the body can generate. Open it and the arm is on its own, running on shoulder and triceps, cut off from the engine.

It is not really about protecting a target. It is about whether your arm is still plugged into you, which means it runs in both directions.

To strike, you must open

In kendo, the basic strike; shōmen uchi raises both arms overhead. The flank opens, it must not open. Modern kendo punishes that with dō, the cut to the torso, usually as nuki dō or kaeshi dō. Thrusts are restricted to the throat, so the armpit itself is not a scoring target. In the older armoured traditions it very much was, which is why the wakibiki existed.

Judo makes the trade plainer. Watch a hundred uchi komi for seoi nage (shoulder throw) and you are watching somebody deliberately open their own underarm to insert it beneath their partner’s – the exposure is not an error. It is the entry.

Then judo names it out loud. Waki gatame. (armpit lock). Your armpit clamps their extended arm and the elbow breaks against your body. The same region is both the vulnerability and the weapon, depending on who arrives first.

The position of strength

We talk about the position of strength, where the arms stay close to the torso and the elbows inside the frame of the body. We talk about the position of weakness, where the arms stray or are forced from the centre. Every white belt hears this in their first month, most brown belts are still working on it.

What almost nobody does is get precise about how the arm leaves, there are three departures and they are not the same:

1. The elbow can cross the centre line. This feeds the armbar, the triangle, the anaconda and the d’arce. Once your elbow is on the wrong side of your sternum, your opponent has an angle you will not recover with strength.
2. The elbow can extend forward through the sagittal plane. The arm stays tight but reaches, and it is met by the arm drag, the duck under, the shoulder throw. Nothing flared – you offered length.
3. The elbow can open through the frontal plane. Out to the side, away from the ribs. Kimura and americana country. The shoulder is now a hinge somebody else can operate.

Three exits, three families of consequence.

Tell a student only to keep their elbows in and you have given one instruction for three problems. Name the departure they just made and they will start to feel it coming.

Reverse it and you have your attacking game. Every upper body submission begins by opening somebody’s wakinoshita. That is not a metaphor, it is the mechanism. You are not trying to beat their body, you are separating an arm from it, because an arm on its own is a lever, and a lever is something you can finish.

Isolation first. Submission second. Always in that order, whether you noticed or not.

Where to train the awareness

None of this becomes real by reading it, attach it to things you already do badly.

Start with shrimping. Everybody drills hip escapes and almost everybody stops paying attention after the third one, elbows wandering out for balance. That is the exact habit you are trying to remove, rehearsed hundreds of times a week. Shrimp with your elbows connected to your ribs and you are not just moving your hips, you are training the shape you want under pressure.

Then your stand up. Most over-reaching is a distance problem wearing a grip fighting costume. If you have to lean and stretch to make contact, you were too far away to start with, and the arm you sent out to fix it now belongs to somebody else. Stay in the pocket. Manage the range rather than the reach and you are never out of position to attack with grips or defend when they are not there.

Then randori. Do not try to fix anything. Notice the moment it goes, which departure it was, and who caused it. Awareness first and correction follows on its own, faster than you expect.

Closed by default, open by decision

The answer is not to grip up like a tin soldier and never let an elbow move. You cannot underhook without opening your own underarm. You cannot frame without extending. You cannot escape side control or take the back without giving something up. Total closure is not defence. It is paralysis with better posture.

So the rule, after more than thirty five years of failing to state it clearly. Closed by default, opened deliberately, briefly, under your own load. Never surrendered.

The other room’s

This does not stop at the dojo door. Ask any decent yoga teacher about overhead work and you will hear “pack your shoulder”. Scapula down and back, arm connected to the trunk, joint not running loose. World-class powerlifters retract and depress their shoulders for benching: “shoulder blades together and down”, they’ll also “pack the lats” when deadlifting – the language is different, it’s a different room, different clothes, entirely different purpose. Same instruction. Same discipline.

When an armourer, a Karateka, Judoka, and a yoga teacher arrive at the same place by four separate routes, it is worth paying attention. Pay attention to yours. Not as a technique to drill, but as a question to carry into every round. Where are my elbows, and did I choose that.

Most of the time you will find you did not.