How Does Judo Work? Throws, Balance and Winning With an Opponent's Weight

Jujutsu was the unarmed fighting of the samurai, meant for a warrior who had lost his sword, and it included strikes, locks, throws and techniques for killing; by the 1870s, with the samurai abolished, it was taught in scattered schools and regarded as disreputable. Kano, a small and frequently bullied student who had learned it to defend himself, saw that the throws and holds could be made into a system of physical and moral education if the dangerous parts were removed and the rest was practised at full force against a resisting partner, and he opened his school, the Kodokan, with nine students in 1882. He replaced the word jutsu, technique, with do, way, and the aim was to make the body efficient and the character calm; the sport was a by-product of the training, and the training was the point.

Every judo technique uses the opponent's balance. A person standing has a base, their feet, and a centre of gravity above it, and they fall when the centre is moved outside the base; judo is the art of moving it there, by pushing when pulled and pulling when pushed, so that the opponent's own effort carries them past their support, and then by placing a hip, a leg or a foot where they will trip over it. Kuzushi, breaking the balance, comes first, then tsukuri, fitting the body into position, then kake, the throw itself, and the sequence is the same whether the throw is a hip throw, a shoulder throw or a foot sweep. A strong opponent who resists with force is easier to throw, since force has direction and direction can be borrowed; the hardest opponent is the one who is relaxed.

A judo match is won by ippon, a full point that ends the contest at once, and it is awarded for a throw that lands the opponent largely on their back with force and control, for a pin held for twenty seconds, or for a submission to a strangle or an arm lock, signalled by tapping. Lesser throws score waza-ari, and two of those make ippon. Penalties, shido, are given for passivity, false attacks, stepping out and illegal grips, and three of them lose the match. The techniques allowed:

• •Throws, nage-waza: hip throws, shoulder throws, leg reaps, foot sweeps and sacrifice throws in which the thrower falls too
• •Pins, osaekomi-waza: holding the opponent on their back under control
• •Strangles, shime-waza: pressure on the neck with the collar or the forearm, released at the tap
• •Arm locks, kansetsu-waza: hyperextension of the elbow only; locks on other joints are banned
• •Banned: strikes, leg grabs in competition since 2010, and any attack on the spine or the small joints

The first thing a beginner learns is how to fall. Ukemi, breakfalls, teach the body to hit the mat spread out, slapping with the arm to spread the impact, chin tucked, and to roll out of a throw, and a judoka does thousands before being thrown in earnest; it is why judo can be practised at full force by children and by seventy-year-olds, and why the sport's injury rate is lower than rugby's despite people being thrown onto the floor all day. The skill transfers. Studies of falls in the elderly have tried teaching breakfalls to prevent hip fractures, and a judoka who is knocked down in the street generally gets up. The philosophy of the throw is that the person thrown is not hurt, and the training is built to make that true.

Judo entered the Olympics in Tokyo in 1964, was won that year, in the open category, by a Dutchman, which was received in Japan as a national shock, and has been contested since with women's events from 1992; it is practised in nearly every country, by an estimated 20 million people, and France has more registered judoka than Japan. Its offspring are its measure: Brazilian jiu-jitsu descends from a Kodokan judoka who emigrated in 1914, sambo was built from it in the Soviet Union, and mixed martial arts drew its grappling from both. Kano's other legacy is the coloured belt, which he introduced to show rank and which every martial art since has copied; he died in 1938 on a ship returning from the Olympic committee meeting that had awarded Tokyo the 1940 games that the war cancelled.

Judo is the grappling sport Jigoro Kano built in 1882 from samurai jujutsu, in which an opponent is thrown, pinned or made to submit by breaking their balance and using their own momentum, on the principle of maximum efficiency with minimum effort. A match is won by ippon, a decisive throw, a twenty-second pin or a submission, strikes and most joint locks are banned, and the breakfalls learned first are what let it be practised at full force safely and what made it an Olympic sport in 1964.