A Kettlebell, formerly also called "round weight", is a training device for free weight training. In contrast to many training devices in fitness studios, Kettlebells are free weights and do not address isolated muscles but muscle groups in the whole body - every exercise is also a coordination task. The goal of training with the ball barbell is above all to build up functional strength, explosive power and stability and to strengthen the cardiovascular system as well as tendons and ligaments. The exercises have a particularly beneficial effect on core strength in the lower back and hip area.