Invented by the Russians way back in the 18th century, kettlebells have a handle that is attached to a bulbous weight and like dumbbells you can get them in a range of differing weights. They worked their way through the military forces in Russia and then the US forces in the far more recent 20th century. Kettlebells have only been fairly recently introduced to public gyms who have now made us all aware of this training technique. How do Kettlebells work?