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Andrew Sheldon-...
Andrew Sheldon-Thomson's picture
Using Modern BioMechanics For Better Stances


I have been looking at using biomechanics to improve my stances.   Consquently I have made them a lot shorter and narrower and have found I can move much better than before.

Here are some of my personal notes on the subject as some of you may find it of value.   (Beware this might be a bit dry for most people)  It sort of addresses the fact that I think most peoples karate stances are too long and wide.   They may look great but they are suboptimal.   I think this is clear as most people shorten them to some degree when sparring.  Any feedback or thoughts welcome.

Stances Are Indivudal

Stances are about movement, they should not be fixed static positions.  Instead with stances your aim is to maximise what is available to you in your body.   Optimising an individual’s mobility and structural strength.   Modern podiatric medicine shares this objective using biomechanics assessment to help achieve it.   As such we can apply some medical analysis techniques to enhance the application of our karate stances.

The problem with most methods of finding the correct stance is that they are applying general rules of thumb.   Stances need to be tailored to the individual as the optimum position for individuals may vary depending on their unique bodies structure.   Even when they appear on the surface to share general characteristics.   Or people get told general things like feel the right position.   This is often unhelpful for people who have practiced the wrong position to the point it feels comfortable to them.

It is therefore necessary to calculate the correct dimensions for you as an individual not take a cookie cutter approach to stances.

Using Biomechanics To Determine The Correct Stance Dimensions

One of the reason that people end up with incorrect stances is that they simply do not know what the optimum position is and therefore do not know what to aim for.

When we understand what dimensions aiming for in our stance, we can use modern medical techniques to locate these dimensions.  We can either do this using a quick approximation method or using a more time consuming but more accurate method taken from a biomechanical GORT assessment.

Long Fighting Stance Dimensions

The long fighting stance length should be your maximum stride length.  It is the maximum length that you can step without becoming unstable.  This makes sense because we want to move as far as possible with each step without compromising our structure.

The long fighting stances width should be your natural base of gate.   This is the optimum point for stability and movement.

Quick Method – Less Accurate

Your inside leg length will be ¾ of your maximum stride length.   A rough calculation of the length of your zenkutsu dachi can therefore be made, by dividing by the leg length you buy trousers in, by 3 and then multiplying by 4.  Or you can measure your leg for a more accurate read.  This method can be out by a few cm.

The width of the stance can be calculated quickly (but slightly inaccurately) by having someone place their feet together.   Then push them on the shoulder from the side firmly but not excessively.   They will naturally step out to their natural base of gate.   Tell them not to move their feet when they land.

Slower Biomechanics Method – Accurate

We can also calculate natural base of gate by utilising a method used by doctors in a GORT assessment to calculate the correct stance length and identify muscle imbalances.

To do this we simply walk up and down on the spot.   We do this for a minimum of three minutes for a basic reading but ideally, we would do this for five minutes.   This is to remove all muscle memory and to get your body to go to its natural position.   It is very important you do not stop moving at any point.  Do not do anything weird well walking like skipping of short steps or over marching, this will make the result inaccurate.   Once you have walked up and down for the prescribed time simply stop.   Use a natural step and do not look at your feet when you do this.   Your feet will be at the width of your natural base of gate (width of zenkutsu datchi). 

You may want to have some tape or chalk near at hand to mark the distance. 

Repeat the process if you think you have skewed the results by artificially stepping or moving – remember you want your natural movement without muscle memory.

If one foot lands significantly forward of the other when you do this, then one side of your body is stronger than the other.   This will likely result in either knee, hip or back pain/problems either now or in the future.  Most hip and knee replacements come from this imbalance.   So it may be worth getting an assessment and correcting this muscle imbalance if you have it.  It will also improve your karate stances if you sort this out.

To calculate the length of the stance we simply repeat the process.   Walk up and down for 3-5 minutes.   Except this time we will take a natural step forward.   This gives us our short fighting stance length (han zenkutsu dachi).   Repeat the process but this time step back at the end.   You need to do this for both sides of the body as left and right may be slightly different if your muscles are not perfectly balanced (most people).

Then add the length of the step forward to the step backwards together.   As you have measured one of your feet twice (ie 3 feet) you need to deduct the length of one of your feet from this combined measurement.   This gives you your long fighting stance length.   If it does not feel strong and stable then you may have a poor reading so repeat the process to get a better one.

Big Toe Lifts & Bobbing Up and Down In Stance

When people lift their big toe up before moving forward in a karate stance they do so because their stance dimensions are wrong and either being too wide, too long or both.   In other words they have an overextended gate.

The toe lift creates an unstable base.  This is a response to supination of the foot.

Supination is when people walk on the outside of the foot.  

We can see this if we kneel down and put our hand on the floor.   Then apply pressure to the outside edge.   This causes index finger to lift off the floor.   The same thing is happening with your toe.   If you look at the arm, the limb will be bowed in this position.   Rather than being in as anatomical position where the structure is naturally supporting itself..

You have to pronate to toe off.   This lets you use your foot as a leaver to push forward.   When you supinate (the opposite of pronate) you are unable to use your foot as a leaver so the only way you can move forward is to throw your weight forward.  This puts pressure on the front and lateral boarder of your knee risking injury.   This throwing of the weight forward causes you to over stride.  In turn this leads people to bob and roll up and down as they move forward in stance.  And because their centre of gravity is too far forward they will do a slight hip rock as they lift the toe in an attempt to stabilise themselves.

Supination is a destructive foot position.   It puts increased pressure on both knees and stretches the hip joint of the non-weight bearing side.   This in turn stretches the lower back causing potential pain, injury and damage.  It can in extreme cases lead to strain on the neck as it can become over stretched as you move well your brain attempts to keep your eyes on a horizontal line.

Knee Cave

When people in overextended stances move we often see their knee cave in.   This is caused by an initial supination of the foot which the body over compensates for with excessive pronation (walking on the inside edge of the foot).   This causes the knee to rock inwards as they move.   This puts strain on the knee and its ligaments.   If you look at any MMA fighter who has experienced an ACL injuries you will likely see this knee cave in their movement.  

The solution to this is to adjust the dimensions of your stance so they fit with the natural structure of your body.  Do not force your knee to travel straight forward in this position.  Instead adjust your stance so your knee naturally wants to travel straight forward.

Overextended Stances, Hips That Stick Out

If you are in a stable stance your centre of gravity will be within the line of your body.   Your hips will naturally sit directly under your shoulders as your body naturally lines up behind it.  A stable body is automatically naturally upright.

If your stance is too long you will lean forward as your centre of gravity moves forward of your chest.   This leads to the hips sticking out behind your shoulders and causes a slight forward body rock as you step forward.

Instructors often tell people to push their hips in or to tuck their tail bone.   Do not do this.   You want your hips to naturally sit under your body.   You do not want to artificially force them under your body.   If you force them under your body you are masking the symptoms of an incorrect stance.   You are not treating the root cause which is incorrect stance dimensions.

You should aim to keep your center of gravity with in the line of your body to facilitate maximum mobility and flexibility of movement.   Once your center of gravity moves outside the line of your body you may have to bring it back in order to change vector.

Treat The Cause Not The Symptoms

In zenkutsu datchi, big toe lifts, bobbing up and down, forward leans, hips behind the body and rocking either side to side or forward and back are all signs that your stance is unstable.   The cause of this instability is incorrect stance dimensions.   It is therefore the stance dimensions that need corrected.  Do not attempt to treat the symptoms.

We often see people train themselves to mask the visible symptoms of their weak stance.   They stop their toe lifting or force their hips under their body.   Covering up symptoms of a weak stance and even if someone can obtain a high level of strength through practice does not change the fact that the position is sub-optimal.   If the same training was put into a correct stance they would be even stronger.

Other Stances

Your kiba dachi stance can be calculated by doubling your natural base of gate.   The shiko dachi will also be double the width of the base of gate but the toes will extend beyond this measurement.   Stand first with the toes pointing forward, then keeping the centre point of the foot where it is push the toes outside the measurement of double the base of gate and pull the heels in.

The body is structured for moving forwards not backwards.   Stride length will therefore be longer on stances that move forward than on those that are designed for a backwards movement.   You would therefore use your backwards step to work out the length of your cat stance (neko ashi dachi). 

Heath White
Heath White's picture


This is really great.  I think more people should be approaching stances with this attitude.  A couple of thoughts and questions:

- If you look at Funakoshi's early books, his stances are a lot shorter than they become in later Shotokan.  Shorin-ryu stances today remain relatively short.  So I  think there is a lot of historical precedent against the long stances you see in a lot of karate today. 

- Keeping my front stance and fighting stance  the width of  my natural gait would be too narrow for me, I think.  I like them a little wider.  Is there a reason you think they should be that width?

- OTOH using "long stride forward" and "stride backward" as the length for front/back stance seems like a very good measurement.

- I was not exactly following the business about supination of the foot.  How about this: if I am in front stance, at  what angle should my rear foot be pointing?

- As I understand it, the reason for tucking the tailbone is to create more power when punching.  The idea is to  eliminate the S-curve (a natural spring) in  the spine: raising the head straightens out the top of the S,  while tucking the tailbone eliminates the bottom of the S.  Then you have a straight(er) bone  chain from fist to floor.  If that is the reason for tucking the tailbone, then there  is no reason to *stand around* like that; you would only do it when executing the punch.  Food for thought.

As I said, a great line of thought to pursue.

Andrew Sheldon-...
Andrew Sheldon-Thomson's picture


The reason I would make the stance width the base of gate is that it is the position that optimises your movement and structural strength.   If you go either narrower or wider you lose one or the other or both.   That said lots of pro MMA people successfully use a wider stance than this.   So you can be very effective in a wider position.   But you are putting strain on your body by doing so.   Esentially this base of gate is the position doctors use when doing things like sorting muscle imbalances or teaching people to walk again.   Its the position that maximises stability and movement.   Which to me sounds like a good position for our stances, but it is kind of my own theory so I am happy to proven wrong with something better.

My point about the tail bone is that if your stance dimentions are correct then your hips will naturally sit under your shoulders and your back should be straight anyway.   So there is no need to artificially straighten it.

I don't know about where the rear foot points.   I just keep it where I always have at a 45 degree angle on the outside edge.   I have no reason for this other than the fact it is what I was originally taught.  The front foot wants the force to travel down the centre of it (except a slight pronation when you push off the toe).   You don't want to walk on either the outside or the inside edge of the foot as you are unstable (sub-optimal) - incorrect stance dimentions cause this.

John Van Tatenhove
John Van Tatenhove's picture


Using modern bio mechanics for any karate moves is priceless.

One concern is that as stances are for transferring body weight, not for standing in, what is optimal will change based on the technique.

For an example, I would use a stance similar to Zenkutsu datchi to push a car out of the snow (Living in Michigan this is something I have done several times), and this would be a rather deep stance. I would use a much narrower stance to shovel snow( I really should move somewhere warm).

If you video tape drills or sparring, you will see Zenkutsu datchi appear and disappear very quickly during the execution of techniques. You may see very high stance when using a jab, but it will be much deeper if you are doing a throw.

The way I was taught Pinan Nidan, Gedan Barai was performed in a deeper stance than the Age-Uke even though these techniques are done back to back.

Tau's picture

Regardless of whether you're a Goju practitioner or not, if you're a serious karateka this book is essential reading, IMHO:


Your initial post is excellent. This book (or training with Kris) will take you to another level.