Hojo Undu is the weight training used to strengthen target muscle groups, strengthen the tendons around vulnerable joints, and to practice movement that are found in the Katas. They are an esentual part of the martal arts experience, aiding in the development of the students physical ability to properly and effectively execute the techniques.
Listed below are three different items that were traditionally used. Originally they were items that were easily come by, either cheaply or for free. Keeping with that tradition, there are materials lists as well as instructions on how to build them utilizing materials that can be located easily.

Chikara Ishi


            There is one of two ways that the students can obtain their own Chikara Ishi (Strength Stone). The first it to purchase a 4lb or 8lb sledge hammer from any home improvement store and cut the handle down to 12 inches.
The second is a little less expensive and can be made with mostly found items. The only expense is the concrete that cost about $3 a bag and can be used to make multiple weights. To make a Chikara Ishi at home, a person needs the following items:

  • Sports drink bottle (32oz for a small weight or 64oz for a large)
  • Old broom or mop handle at least 1 inche in diameter
  • Concrete
  • Nails or screws
  1. Take the Sports drink bottle, remove the label and cut it just as the bottle begins to taper up to the mouth.
  2. Next cut the handle to about 16 inches for the small or 18 inches for the big weights. This will leave a 12 inches handle when it is all done. Next place nails or screws around the bottom of the handle. This is so that the concrete has something to hold on to and the handle does not fall out.
  3. The next step is to mix up the concrete. It is very important that it is mixed correctly. The type of concrete is also important. Do not use a quick set or a light weight mixture. This will result in a weight that is to light and weak.
  4. Pour the concrete into the bottle, and insert the handle. Very slightly move the handle up and down to remove any air bubbles. Smooth the top to insure that there is no rough edges that will cut the hands while using.
  5. Place aside for several days to cure completely.

Ishi Sashi


            Ishi Sashi (Stone Lock) are traditional weights that are used for various exercises. They can be bought or made at home using common concrete. However, the homemade versions require a mold from which they can be cast. The process of making the mold is very difficult and required many different tools and skills in which to make it.

The dimensions of the pictured Ishi Sahsi are:

  • Base: 4 inches by 9 inches
  • Top: 1½ inch by 9 inches
  • Height: 6 inches
  • Handle: 6 inches in length by 1½ diameter
  • Weight: 8 pounds

There is a different solution. It costs more, but can be made much easier. Get a red plastic gas can. Fill with playground sand, and recap the end. The gas cans are sold in different sizes, allowing for different weights when filled.

Nigiri Game


            Traditionally Nigiri Game (Gripping Jars) were just jars used for foodstuff. They were readily available items that could be used for strength training. They would be filled gradually with sand, stones, or water. Since all the components were free and readily available, it made a great training tool at an even better price.
Unfortunately, the jars can no longer easily be found. There are places that can make them, however getting custom made Nigiri Game can be expensive. It is, however, very rewarding if one can find a potter to undertake the work.
The alternative is to make ones that function the same while using modern materials. This can be accomplished with the following materials items located at any home center:

  • 4-inch diameter PVC tube
  • 4-inch PVC coupling
  • PVC glue
  • ½ inch thick Plywood
  1. First cut the PVC tube to the desired length.
  2. Then cut the Coupling into ½ inch thick pieces in order to make the griping lip. To get the lip uniform is a very time intensive process. Take your time. Then using sandpaper prior to gluing into place, round the edges so they are not sharp.
  3. For the bottoms, cut the plywood into disks and fit them into the bottom of each tub, creating a flat bottom. Using woodscrews, secure the plywood into place.

The only problem that was found with this design was that the narrow bottom made the Nigiri Game unstable, and would easily tip over. This could be very messy if they were filled with sand, stones, water, etc. To remedy this, make small weights using 32 oz sport drink bottles filled with concrete. Adding or removing the weights can easily adjust the difficulty, and the fit is perfect.


Training Stones


            The training stones that Sensei Brain Nell uses are based off the research of David Elkins and Rik Lostritto with one difference. The training stones that Sensei Brian Nell uses are made from wood, not granite. They serve the same function as the original ones, but are more easily balanced and customized. Since they are hollow, sand is added or taken away, to increases or decrease the weight, and give a wider range of functionality.

  • Size: 7 inches x 5½ inches x 24½ inches.