Shiwari

'Shiwari' or 'Tameshi wari', is breaking boards, ceramic tiles, etc with bare hands or feet.

The purpose of shiwari is to see the impact of the technique after having long time serious training. But trying beyond your capability and having injury is nonsense.
I love to watch or try by myself, but dislike kids are doing this because it must give bad effect to their bones.
Breaking baseball bats, concrete blocks etc. are good for entertainment, but not for shotokan karate.
If it is conducted properly under supervising by trained sensei, it is good encouragement for students too. What do you think?