8kg Cast Iron Kettlebell Kettlebell training has taken the fitness world by storm. In just a few years; there are now thousands of people in the United Kingdom that are benefiting from the benefits of kettlebells. In addition; to everyday men and women; many athletes from a variety of sports now use kettlebells in their programs. Kettlebells look like shot putts with a handle and have been used in training the Russian army for centuries. They work a complete range of muscles as you swing the kettlebell backwards and forwards or from side to side. There are cardiovascular benefits also.