Albert Barnes Commentary Judges 5:22

"Then did the horsehoofs stamp By reason of the prancings, the prancings of their strong ones." — Judges 5:22 (ASV)

Probably an allusion to the frantic efforts of the chariot-horses to disengage themselves from the morass (Judges 4:15, note).

Mighty ones - Applied to bulls (Psalms 22:12) and horses (Jeremiah 8:16; Jeremiah 47:3; Jeremiah 50:11); elsewhere, as probably here, to men.