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Tighten the loop in judo

Hey what's up? So I have a new blog post today and once again it's about judo. My reflection today is from a podcast I heard recently about the employement of the OODA loop in the armed forces.

OODA loop quickly

The OODA loop (observe, orient, decide, act loop) is a decision-making model developed by United States Air Force Colonel John Boyd in the early 1970s. [...] The approach explains how agility can overcome raw power in dealing with human opponents.

So the OODA loop is a decision-making loop, and I think the link between raw power and agility to defeat an opponent applies interestingly to judo... in a different way than one could imagine

Judo isn't about decisions, it's about reaction

Judo is fast, like really fast and especially in competition (see shiai for more details). Thinking about the technique and executing it is very rarely how it goes: you see an opening or an opportunity and you react by reflex with a technique or situation from training. A lot of it is making your grip and your position as comfortable as possible for your best technique to be effective. This cannot work if you have to think during the fight.

The average reaction time of a human is 0.25 seconds when dealing with something visual, so if you need to see or feel the technique, think about it's application and enact it, you are looking at close to half a second to execute a throw. In half a second, your opponent as already recovered their balance.

Impose a decision loop on your opponent

I surmise a theory, that if you are able to impose a decision loop like the OODA on your opponent, you force them to stop "reacting and executing" and more thinking and acting. It costs them time, energy and increases their stress as well as creates opportunity for you.

When your opponent has to react to your ko-uchi/ouchi and then to take a step back, you are already making them extend their time and create a decision loop:

  • "Do I defend? what is he going to do next?"
  • "How can I attack? I feel his ko-uchi is particularly vicious, maybe I should pay attention to that"

Generating charos

The core of the OODA loop in armed forces is to increase one's loop to maximize actions in real battle scenarios, while disrupting your opponent's. Disrupting your opponent's decision can rely on several factors:

  • Disabled detection (think taking out radar stations, creating smoke and such, so Observe)
  • Broken communications (Orient and Decide)
  • Stop fuel lines (Act)

I believe that by pushing your opponent with precise attacks and a good kumi-kata/disruptive techniques, you are effectively introducing chaos in a similar way with your opponent. I can say that I have experienced such situations even with lower belts than me, attacking aggresively and decisively against me, even though they were technically worse.

This is something to try, but this quick reflection was interesting for my part.

Let's go for 2026!

What's new?

Alrighty, let's go for 2026, honestly I have had quite some fun working again on this site, and I'm looking forward to 2026.

Judo competition picture

This is me above before my second match (and last) of my competition in December 2025. I need to compete more and encourage those interested to try it as well. It's loads of fun.

Right now I took some time to think about building a page and a space for judo, mostly focused on the Czech Republic side of it. Let's see how it goes. The objective is to consolidate what there was on Notion and what we worked on with Kuba for my blue belt's exam in November 2025.

Technology?

The blog

The website took some time to update, but I think I start to be satisfied with how it looks. It's based on Material for Mkdocs, so a tad simpler to use than the previous one I had a couple of years back with Netlify and Gatsby. The biggest improvement is also the GitHub Actions that are very fast to deploy.

Another thing to do to improve the website, beyond content, is to integrate some form of comment system. I'm going to likely try Giscus. But I need some time to set it up.

Other stuff

I haven't been idle on the other fronts but haven't posted for quite some time... So right now I've learnt a few things in Airflow, like dags and so on; as well as, connecting to LLMs through APIs, which is useful.

2 years ago already I did an internal bootcamp on LLMs where I scored th highest for it in terms of points. Eh, happy about it, but I'm certainly no expert.

I have some ideas to write, perhaps about distributed computing and setting up teams, but quite honestly right now I'll focus on stuff I like. For the moment: judo!

Let's kickstart the end of 2025

Revival or returning to writting

Initially, this blog was created over 6 years ago, a bit before COVID at a time I thought would be great to share fresh ideas I had. I was building a BI application with open source software and learning the ropes on some infrastructure as code.

Then, I was also perhaps a bit lacking in quite a lot of area in IT, but I had a sharp mind for programming. Now I have learnt a bit more but I am STILL lacking in quite of lot of area in IT, data processing; governance, security... Well nobody's perfect.

The issue is that over the past 2 years, AI and LLMs are everywhere, suggesting code to programmers, compiling notes, being talked as the new frontier in technology and a revolution. There is something to learn in that space and maybe this is the place where I'll start to write.

A page is turning at the end of this year, and I am reviving this blog for that. Let's see how far I can take it.

Wedding information (EN)

Hello everyone, We had a small wedding in February, but we want a big celebration with you! That's why we would like to invite you on September 13, 2025 at 1:00 PM.

“Okay, but where?”

Velký Mlýn!

U Českých loděnic 40, 180 00 Praha 8 – Libeň

How to get there?

The best way to get there is by tram 3 or 24 to the stop "Libeňský zámek" if you come from the center. From there, it's a 5-minute walk.

“What will happen?”

  • 1:00 PM Start
  • 2:00 PM Vows
  • 6:00 PM Cake cutting
  • And then? Party!

(We have to stop making noise at midnight, but that should be alright!)

No seating plan, it will be a buffet and just a moment to share with friends and family.

“How can we help you?”

We are not planning anything complicated, but if you would like to show off your culinary skills, we would be very happy for sweet and savory treats!

Contact: svatba@chevallier.dev

Otherwise, food, beer, wine and soft drinks will be taken care of.

“Celebration? And music?!”

We will have instruments and equipment for a jam session and a speaker to put some music when live jammer are unavailable. But be careful, we have veto power over the playlist!

“What about gifts? And the dress code?”

We would love for you to come and have a great time with us. If you couldn’t help but want to give us something, we would be happy to contribute to the renovation of our apartment (you can go to this link).

There is no dress code, come in whatever way you feel comfortable and pleasant!

We look forward to seeing you all!

“Can we bring children?”

Of course! The more the merrier!

“Where is the best place to stay in the city for the weekend”

Okay, we are not going to lie, we can't accomodate everyone in our apartment. But there are many options in Prague, and we can help you find something that suits your needs and budget.

We recommend looking for accommodation around Namesti Republiky or Karlín, which are all well connected by public transport and have a lively atmosphere with many restaurants and cafes and not far from the venue.