P. Heesen, The J. L. Theodor Collection of Attic Black-Figure Vases, Allard Pierson Series, 10, Amsterdam, 1996, pp. 70-72, no. 9.
Heesen suggests that "... the subject is most likely youths training at an armed dance in a palaestra [Pyrrhic dancers]... The Pyrrhic dance was performed nude in choral competitions at the Panathenaic festival and associated with Athena who, according to legend, performed it when she was born from the head of Zeus and after the gods defeated the Giants. As a rule, vase-paintings show young men practising the dance, not the competition itself. It has been stated that the Pyrrhic dance was used for military training during the 5th century because it emphasized manoeuvres with a shield ... Apart from the standard arms (helmet, round shield, lance), dancers may also be equipped with greaves. Further, many scenes of these dancers show a camp-stool on which garments are piled, ... The painter of this oinochoe seems to have instead depicted a thick blanket, possibly made of wool. The feet of the right-hand dancer are high above the ground, as if he is jumping."
Also, cf. H. A. Shapiro et al., Greek Vases in the San Antonio Museum of Art, San Antonio, 1995, no. 56 for a pelike with similar subject attributed by Beazley to the Theseus Painter, "The contestants represented their respective phyle, or tribe, and were financed by a choregos (sponsor of a theatrical performance), just like the theatrical companies that performed at the festival of Dionysos. Prizes were awarded on the basis both of how well the pyrrhics were equipped and how they executed the prescribed movements. From the orator Lysias (21.4-5) we even learn how much it cost the choregos to sponsor a team in the pyrrhich in the late 5th century: 800 drachmai at the Greater Panathenaia, 700 at the Lesser Panathenaia, the smaller festival held in each of the intervening three years."
See illustration on page 44.