There's a lot to unpack when it comes to understanding the rules of rhythmic gymnastics. You may have seen the performances with the acrobatic moves and the four different objects the gymnasts must manipulate but may not have understood what the judges are looking for.
First, the basics. There are both individual and group competitions. Only women perform in rhythmic gymnastics. The competitions are performed on a 13-meter by 13-meter mat. Like with the floor exercise in artistic gymnastics, the performances are done to music.
Keep in mind as you read these, these gymnasts are leaping, flipping and tumbling both when these pieces of equipment are in their hands and when they are throwing them into the air.
A long satin ribbon connected to a stick is used. Gymnasts must keep their wrists constantly moving. If a knot forms in the ribbon, it's a deduction. If the ribbon breaks, it's a deduction. If the ribbon is dropped, it's a deduction.
The hoop is made of plastic or wood. It can be thrown in the air and caught, be used for rolls over the body or on the floor or be rotated around the hand or other parts of the body. It's probably stuff you tried as a kid with a hula hoop. But if the hoop wobbles in the air when it is thrown, there is a penalty.
These performances are about elegance and lyricism as well as athleticism. The ball is made of rubber. Gymnasts can roll the ball along their body in addition to throwing and catching it. But the throws and catches can get pretty elaborate. Some of the best can throw the ball in the air with their foot, do a couple of spins, then catch it behind their backs while doing a flip, just as an example.
The clubs are about 15 inches long and weigh only about 1/3 of a pound. Imagine really long sticks, not clubs you might see jugglers use. Gymnasts must show they can manipulate both clubs in different ways simultaneously, such as throwing one into the air while twirling the other. Dropping the club can lead to a penalty, but they can touch the floor if it was clearly intended as part of the routine.
Individual gymnasts must perform four times using each piece of equipment: ribbon, ball, hoop, and clubs. Each performance must last 75 to 90 seconds. Going over or under is a 0.05-point deduction for each second.
Group competitions involve teams of five. The groups perform together at the same time in two exercises. On the first one, all five members use balls. On the second exercise, they use three hoops and two pairs of clubs. (At the 2016 Games in Rio, it was one exercise with five ribbons and the other with three pairs of clubs and two hoops). Performances must go 2 minutes 15 seconds to 2 minutes 30 seconds with the same deduction for going over or under.