Bokkens, which are wooden swords used in Japanese martial arts training, are generally durable and designed to withstand the impact and stress of training. They are typically made from solid hardwood, such as oak or hickory, which provides strength and resilience.

However, while bokkens are designed to be sturdy, they are not indestructible, and under certain circumstances, they can break. Factors that can contribute to the breakage of a bokken include:

1. Poor quality or improper construction: Bokkens of inferior quality or those that have not been properly constructed may be more prone to breakage. It's important to choose bokkens from reputable sources that use quality materials and craftsmanship.
2. Extreme force or impact: Bokkens are intended for training and sparring purposes, and they can handle a reasonable amount of force. However, excessive force, particularly when used inappropriately or against hard surfaces, can increase the risk of breakage.
3. Wear and tear: Over time, with consistent use, bokkens may experience wear and tear, which can weaken the wood and make them more susceptible to breakage. Regular inspection and maintenance, such as sanding away splinters and cracks, can help prolong the lifespan of a bokken.
4. Environmental factors: Extreme temperatures, humidity, or exposure to moisture can potentially weaken the wood and make it more prone to breakage. Proper storage and care, such as keeping the bokken in a dry environment and periodically oiling it, can help mitigate these risks.

With proper care, appropriate usage, and regular inspection, bokkens can be durable and long-lasting training tools. However, it's important to periodically evaluate the condition of your bokken and replace it if any signs of damage or weakness are detected.