Speed, control and force are key criteria for scoring in judo

But judo rules still allow contestants to gain a submission by holding them in an armlock or a stranglehold, however, so it is hardly tiddlywinks.

Contests last five minutes for men and four for women.

The two combatants, known as judoka, attempt to clinch victory by throwing their opponent or applying a hold that immobilises them for 25 seconds or makes them submit because they cannot move.

The first person to score a point wins the bout.

JUDO WEIGHT CLASSES Extra lightweight Men -60kg, Women -48kg Half lightweight Men -66kg, Women -52kg Lightweight Men -73kg, Women -57kg Half-middlewight Men -81kg, Women -63kg Middleweight Men -90kg, Women -70kg Half-heavyweight Men -100kg, Women -78kg Heavyweight Men +100kg, Women +78kg

If no one scores a point, the contender with half a point wins and, if scores are level or no one scores at all, the bout is decided by the judges.

Victory by scoring one point is called ippon. The opponent must be thrown onto their back, with control, force and speed.

If one of those four criteria is missing then a half-point is awarded, known as a waza-ari.

A half-point can also be scored for a hold that is more than 20 seconds, but not 25.

Contestants can also score with a yuko or a koka.

A yuko is earned by a throw in which two of the above criteria are missing, or a hold that lasts 15 to 19 seconds.

A koka is awarded if three of the criteria for a throw are not met, or a hold that lasts 10 to 14 seconds.

If a bout is drawn, the number of yuko and koka are counted up. A yuko counts for more, but if competitors have the same number then koka are taken into account.

DID YOU KNOW? Contestants must be clean, have dry skin and have clipped their finger and toenails before a bout - and offensive body odour is banned

If there is still a tie the judges vote, taking into account the aggression shown by each combatant and the effectiveness of their combat.

Penalties play a major part in judo, and contestants are punished in different ways, ranging from a koka for small offences to an ippon for the most serious.

They can be penalised for not showing enough aggression, dangerous play or for pushing a contestant off the 46 square-foot mat.

In competitions, judoka are split into two pools and eliminated on a knockout basis, with the two pool winners competing for gold and silver.

All the judoka who have lost to either of their pool's finalists then compete in a knockout repechage.

The winner of each repechage then faces the runner-up in the other, with the two victors awarded bronze medals.