Παράκειται δὲ τούτοις τὸ πρὸς πυγὴν ἅλλεσθαι, ᾧ καὶ αἱ Λάκαιναι γυναῖκες τὸ πρόσθεν ἐχρῶντο· τοῦτο δ’ ἐστὶν ἄφαλσις, καμπτομένων τῶν σκελῶν, ὥστε τὰς πτέρνας τῶν πυγῶν προσάπτεσθαι, ποτὲ μὲν ἐναλλὰξ τῶν σκελῶν ἀναλακτιζόντων, ποτὲ δ’ ἀμφοτέρων ἅμα.
(Oribasius, Coll. Med. 6.31.1-3)
There are also jumps where they hit the buttocks, like Spartan women used to perform. This is a jump where the legs are bent in such a way as to make the heels touch the buttocks. In this exercise the legs are kicked up either in alternation or both at the same time. (tr. David Bauwens)