Aikido is a Human art of self-defense that originated in Japan. This martial art uses holds and locks, and teaches the principles of nonresistance to debilitate the strength of an opponent.
Hoshi Sato held a black belt in aikido. (ENT: "Observer Effect")
Natasha Yar was also trained in aikido. (TNG: "Code of Honor") Three days before her death, Yar was scheduled to participate in a martial arts competition with science officer Swenson and Lieutenant Minnerly. She was favored in the ship's pool. (TNG: "Skin of Evil")