Tuesday, July 14, 2015


I am obsessed with developing proper koshi. My iai teacher, Kiyama Hiroshi, has been kicking my butt about my koshi for decades, and I’m getting so monomaniacal about it that I wonder why he hasn’t pushed me harder. Whenever I see him, he always makes point to remind to work on my koshi. He is over 90, and still has powerful koshi.

Kiyama Hiroshi Shihan Photo Copyright Peter Boylan 2013

So what is koshi? That’s a little tough, because koshi not a clearly defined medical term. Koshi includes the lower back, hips, waist and pelvis. It may be a little vague, but it’s a really good term for a critical area of the body when doing good budo.  That’s because the koshi is the platform that the upper body rest upon.  If the koshi isn’t solid, everything else will wibble-wobble around without any power or control.

Kiyama Sensei always tells me ”腰を入れて” or “put my koshi in”/”use my koshi.” This is subtly different from what people mean when they say “use your legs” or “put your back into it”. Proper use of the koshi is something more fundamental. Good koshi isn’t just about giving power, though it does that. It also gives stability in a way that is critical for being able to use the power in both your legs and your upper body.

When I swing a sword, thrust with a jo, or throw someone in judo, the quality of the technique is limited by how well I can use my koshi. It is the platform that the technique rests upon. When I swing a sword, does the weight and movement of the sword disrupt my balance and stability? If my koshi isn’t solid, it will. On the other hand, if my koshi is solid, I can increase the power and effect of my swing significantly by small movements of the koshi. The koshi ties my whole body together and allows me to direct all the power of my body into the swing of the sword, the thrust of the jo or a throw in judo.

koshi is related to what exercise instructors and trainers refer to as the “core.” The koshi combines the muscles of the lower back and the lower abdomen and ties them together with the pelvis and hips. The lower back muscles have to work with the abdominal muscles as a single unit. They can’t be fighting each other, and one can’t be overpowering the other. These muscles then attach to the pelvis from above to create a single, solid platform.

The stability of that platform is critical in whatever form of budo you are doing.  Most beginners using a sword will tend to sway back and forth like a metronome when they swing the sword. As a beginner swings the sword down, her body is pulled forward from its balanced position. As she raises the sword back over her head her body comes back to center and sometimes even sways past center to the rear.  Without a stable koshi, the beginner has no balance and no control.

The same problem arises when thrusting with a jo.  A martial artist who doesn’t know how to apply her koshi tends to thrust with just her arms, or worse, tries to power the thrust by tipping her upper body into the thrust. This doesn’t increase the power of the thrust, but it does leave her badly off balance and unable to do anything until she has pulled her upper body back over her koshi.

On the other hand, if you power a weapons thrust by driving forward with the legs and transmit that movement and leg power through the koshi to the upper body to the arms and then the weapon, you get a very powerful technique that can actually pick up and move someone (if you can find an uke who is willing to suffer through this). The koshi has to be rock solid for this to work. If there is some point where the hips, pelvis, abdomen and lower back aren’t properly connected, the moment your thrust encounters solid resistance everything will fall apart. Without a solid koshi, when you thrust into a solid partner (someone with great koshi!), your own energy will force your upper body to bend back, away from the target, even as your legs and hips are driving forward. This is disasterous.  The thrust loses any effect on the target and instead knocks you backward and off balance.

Koshi is fundamental. Nowhere is this more true than in empty hand arts. I was watching some budo demonstrations on youtube, and what consistently stood out to me was that nobody had good koshi.  Everyone demonstrating had weak koshi.  Their bodies were all over the place.  Whenever tori threw uke or took him to the ground in a pin or joint control, tori was leaning into the technique instead of driving with his legs and koshi.

I’m a judoka. If you lean into a throw or a pin, it becomes trivially simple for uke to take control from you and reverse the situation. With a judoka that can mean that three-quarters of the way through the technique, when you are sure uke is going down, you suddenly find yourself in flight going over and past uke before you hit the ground.

So how do you develop koshi? The most obvious first step is to have a solid core. That’s not complicated or mysterious.  There are thousands of sites and videos that detail exercises for building a strong core. I’m not going to spend time going over that ground. I will talk about learning to feel and use your koshi well. The first check is to stand up.

Just stand up, close your eyes and feel where your head and shoulders are in relation to your hips. Because the koshi are so fundamental to everything we do, small changes in the angle and relationship between your koshi and the rest of your body can have outsized effects on your stability and technique.  Where are your hips and pelvis? Odds are if you dropped a plumb line from the base of your neck, your hips would be a little behind it.  

That’s not where you want it. You want your hips and pelvis under your shoulders and your shoulders under your head. Take a look at the video of Kim Taylor above. He does a strike with the tsuka of the sword yet his shoulders and head are never in front of his koshi. All the power of his koshi is punching right through the end of the tsuka. The same thing happens when he turns and does the thrust with the sword. He doesn’t over extend his arm.  He doesn’t lean forward from the waist. He pushes the sword forward from his koshi.

That’s where the real power comes from.  Find where your koshi is, and then adjust it to where it should be. Can you feel the difference? Get familiar with that feeling. Really learn how it feels to stand like that. Now try walking.

It’s more difficult than we expect to move from our koshi when we walk because we have all sorts of habits from everyday life. These make walking difficult to do without paying a lot of attention to it. The upside is that walking is something we do all the time. We don’t have to go to the dojo, and we don’t need a skilled uke to practice moving with good koshi. We can practice this any time we walk, even at work.

The first thing to practice is just walking while maintaining a stable, connected koshi. This is the first step towards having a solid koshi to apply to budo. When you walk, do your head and shoulders stay over your koshi? Or are you a citizen of the 21st century whose head is permanently tilted forward and down, ready to check your iPhone at a moment’s notice? Can you duplicate the feeling of stability you have when standing still with a solid koshi while walking normally?  Once you get that, you’ll be ready to start introducing good koshi into your budo.

Koshi alone isn’t everything, but without good use of koshi, it’s difficult to progress in your practice. 

I want to give a bow of thanks to Deborah Klens-Bigman more editing and advice on this one. You can read her excellent martial arts blog at http://resobox.com/author/deborah-klens-bigman/ 


Thomas Fruy said...

It is perfectly normal. Japanese MA really suck at this.
Koshi is to Dantian what Budo is to oriental philosophy.
An edulcorated deformation.

The Budo Bum said...

I have to strongly disagree with you. 丹田 dantian is very different from 腰 koshi. Koshi is very concrete physical structure with no connection to philosophical concepts that are dantian and the cinnabar field. There is no deformation. Traditional Japanese medicine and movement arts (including budo) are very familiar with dantian. When they mean dantian, they say so. When budoka refer to kyoshi, they know the difference and choose the term that is most appropriate for what is being discussed.

Christopher Li said...

There's part of the confusion - dantian is also a concrete physical structure without connection to philosophical concepts, just in terms of physical arts - although there can be crossovers to the more esoteric once you get into health and meditative disciplines. My experience has been that Japanese budoka go to "koshi" by default but that the explanations tend not to be as fine grained as they could be.

Rick Frye said...

Peter is always on about Koshi with me. My traditional exercise teacher is always talking about engaging the core. We tend to listen with half our head to this advise. Like so many things in our lives we tend to ignore what we hear too often, at first because we do not understand what the words mean in terms of our bodies, then because we have heard it too many times. Like my students used to say when I repeat some bon mot for the millionth time, "It's all good Mr. Frye" and then they just lump along like usual. The point that made me really take the koshi/core advice to heart was working with Sensei Peter with his kusarigami practice. We watched the video and while watching the demonstrator carefully, I SAW it, he moved the chain around the bokkan by using his koshi, not his arm, which is the "rational" way to swing it around. It made all the difference. I now consciously engage my koshi when ever I exercise, riding my bike, doing squats, walking, doing iai. I am much more stable, you can feel the difference it makes.

Ian said...

It all sounds a bit wishy/washy to me, but that's probably because I don't understand. How do you engage a "muscle"/area that isn't even clearly defined? Am I meant to keep my pelvic floor, butt and abs tight at all times? But won't I be too tense then? Or should I just develop a strong pelvic floor, butt and abs and engage them in cuts?

Could you please elaborate? It's really quite difficult to find good koshi-related exercises and advice. Thank you!

Joseph Tomei said...

A little late to this, apologies, work is kicking my koshi, unfortunately.

I'm starting to think that the key for koshi is flexibility. I'm always struck how Judo and Aikido have very little emphasis on flexibility, sumo really emphasizes it, but it's pretty much ballistic stretching rather than relaxation of muscles. Of course, top judoka often have pretty amazing flexibility (I remember a video about the Saito-Yamashita rivalry, with Saito warming up with side splits, and I also trained with a Russian when I was in grad school who had obviously spent a lot of time developing his flexibility) Of course, with iaido, it's really hard to think you are going to work on your flexibility while your sword is waiting to be drawn...

I've started doing Tai chi and the amount of time stretching to actually doing tai chi is at least 2:1. I just wish I'd spent more time earlier developing some flexibility.

chbedok said...

The feeling one gets when one has good koshi, is it a feeling of lightness throughout the body when the structure is set? The feeling that one could stand for long periods of time without feeling sore?

The Budo Bum said...

Thanks for pointing this out. I'm not sure I would say that flexibility is the key, but certainly it is one of the foundational building blocks. All the strength in the wold will be useless without the flexibility to direct it where it needs to go.

The Budo Bum said...

That feeling of lightness is one expression of good koshi, yes. To me, there should also be a feeling of connectedness so that you can direct the rest of your body by adjusting your koshi (I'm not sure how much sense this description makes. Sorry)

Draven Olary said...

Not long ago I found an interview with Kishimoto Chihiro Sensei
Somewhere in the text it was one thing that confirmed again how important the breathing is ...

Draven Olary said...

"Koshi is fundamental. Nowhere is this more true than in empty hand arts. I was watching some budo demonstrations on youtube, and what consistently stood out to me was that nobody had good koshi. Everyone demonstrating had weak koshi."

If you want good informal material, there are very few on youtube. You can try these series:

3 Major Schools of Okinawa Karate - Uechi-ryu, Goju-ryu, Shorin-ryu:
The Dynamic Techniques of SHOTOKAN KARATE - check all of them

Old but good.