Unlike in training using regular wooden swords which have the potential to cause serious injury and even fatal accidents even if trainees strike at their opponents for practice, in training using fukuro shinai, trainees can strike at their opponents with all their might (even so, some trainees may be injured, and trainees often suffer from considerable pain when they are struck).
それまでの木刀を使用した稽古（すべて仮当てだが間違えば大怪我、死亡など事故に至りかねない）とは違って、相手に本気で打ちかかることが出来た（ただし、怪我をする人はするし、かなり痛みも伴う）。