Ishi Sashi

The Gojuryu Karatedo Yoyogi Ryushinkan Dojo is equipped with ishi sashi.

These training tools are hand-held weights in the shape of padlocks, traditionally made of stone.  They can also be made out of iron, in which case they are referred to as a “tetsu sashi.” According to some sources, this tool most probably has its roots in China, where similar methods are referred to as 'stone chain training' and have been used for centuries.  Ishi sashi are used in the hojo undo (補助運動) supplementary conditioning exercises.

Use of the ishi sashi will increase strength in the fingers, wrists, elbows and shoulders.  One exercise with ishi sashi to grip and hold throughout the performance of Sanchin and Tensho to reinforce execution of the various techniques found in those kata, particularly the mawashi uke at the end. This training will also help to develop the ability to root the arm movements firmly in the torso, so that the entire body core, including the lower back, is used to block, pull and strike.

Additionally, ishi sashi can be hooked over the feet to strengthen the legs for kicking and kneeing techniques.

Here is a site with advice on making your own hojo undo traditional training equipment – though plenty of patience and trial and error will most likely be required.