The hoop held symbolic meanings in Ancient Greek myth and culture and was used to represent a boy or youth in general in Greek art. The Greeks referred to the hoop as the trochus or krikoi, and they were probably made of bronze, iron, or copper. They were driven with a stick called the elater. The boys would roll them down the street running along side or have races.
A bronze hoop was one of the toys of the infant Dionysus, and hoop driving is an attribute of Ganymede, often depicted on Greek vase paintings from the 5th century BC. It was a very popular toy among ancient Greek kids and the sport was regarded as healthful, and was recommended by Hippocrates for strengthening weak constitutions. Though there are no images or written accounts, one can imagine that some rambunctious young Greek boy likely invented the Hula hoop 3000 years before Wham-O.
Images of the hoop are often presented in the context of boylove in ancient Greece. A trochus/hoop was a favorite gift given by a Greek man to the boy he fancied  as well as gifts of animals, or meat. A spear, trident, or wooden staff is sometimes depicted (on pottery) penetrating the boy's hoop as a symbolic allusion to the sexual nature of the relationship.
Zeus and Ganymede
The images below are from a red-figure bell Krater depicting Ganymede and Zeus attributed to the Berlin Painter circa 500-480 BC. Kraters were used at banquets for mixing wine and water. Zeus is shown pursuing the boy Ganymede, who is playings with a toy hoop, symbol of his youth, and a cock, a traditional gift given to boys by their male suitors.  The two images taken together convey the pederastic or sexual nature of the relationship.
- Athletics and Games of the Ancient Greeks By Edward M Plummer; p50
- Forerunners and Rivals of Christianity: Being Studies in Religious History from 330 B.C. to 330 A.D. by Francis Legge; 1915 p. 125
- "Hippocrates recommended playing with a hoop as a cure for weak people" Psychoanalytic perspectives on art: PPA, Volume 1 - Page 97 by Mary Mathews Gedo
- The ancient Olympics By Nigel Jonathan Spivey; p48