Through his teaching position and understanding of Japanese martial arts, Gigō became the technical creator of modern shotokan karate. In 1946 the book Karate Do Nyumon by Gigo and Gichin Funakoshi was released. Gigo had written the technical part, whereas his father Gichin wrote the preamble and historical parts.[4]
While the ancient arts of To-de and shuri-te emphasized the use and development of the upper body, open hand attacks, short distances, joint locks, basic grappling, pressure point striking and use of the front kick and variations of it, Gigō developed long distance striking techniques using the low stances found in old style kendo and Iaido kata. Gigo also developed higher kicks including mawashi geri (round kick), yoko geri kekomi (thrusting side kick), yoko geri keage (snap side kick), fumikiri (cutting side kick directed to soft targets), ura mawashi geri (quarter rotation front-round kick—though some credit Kase-sensei with the creation of this technique), ushiro ura mawashi geri (360 degrees turning round kick) and ushiro geri kekomi (thrusting back kick). Yoshitaka was especially known for his deep stances and kicking techniques, and he introduced fudo dachi (rooted stance/immovable stance), yoko geri (side kick), and mae geri (front kick) forms to the Shotokan style.[8] All these techniques became part of the already large arsenal brought from the ancient Okinawan styles. Another big changement of Gigo was the introduction of the Kiba Dachi instead of Shiko Dachi and implementing the Kokutsu Dachi (which he took from japanese classical fencing or "kenjutsu") instead of Neko Ashi Dachi stance in Shotokan Kata.
Gigo's kicking techniques were performed with a much higher knee-lift than in previous styles, and the use of the hips was emphasized. Other technical developments included the turning of the torso to a half-facing position (hanmi) when blocking, and thrusting the rear leg and hips when performing the techniques. These adaptations allowed the delivery of a penetrating attack with the whole body through correct body alignment. Gigo also promoted free sparring.[9]
Gigō's kumite (fighting) style was to strike hard and fast, using low stances and long attacks, chained techniques and foot sweeps (taken from old style Kendo and Judo). Integration of these changes into the Shotokan style immediately separated Shotokan from Okinawan karate. Gigo also emphasized the use of oi tsuki (lunge punch) and gyaku tsuki (reverse lunge punch). The training sessions in his dojo were exhausting, and during these, Gigo expected his students to give twice as much energy as they would put into a real confrontation. He expected this over-training would prepare them for an actual combat situation, should it arise.
https://en.wikipedia.org/wiki/Gig%C5%8D_Funakoshi