What is a Kettlebell?
The kettlebell is a cast-iron or cast steel weight (resembling a cannonball with a handle) used to perform all types of exercises, including but not limited to ballistic exercises that combine cardiovascular, strength and flexibility training. They are also the primary equipment used in the weight lifting sport of kettlebell lifting.
Unlike traditional dumbbells, the kettlebell's center of mass is extended beyond the hand, similar to Indian clubs or ishi sashi. This facilitates ballistic and swinging movements. Variants of the kettlebell include bags filled with sand, water, or steel shot. The kettlebell allows for swing movements and release moves with added safety and added grip, wrist, arm and core strengthening. The unique shape of the kettlebell provides the "unstable force" for handling - key for the effectiveness of the kettlebell exercises. The anatomy of the kettlebell can be broken down into: handle, corner(s), horn(s), window, bell, and base.
Why use a Kettlebell?
Well, there are a number of reasons. Kettlebell workouts can offer a good of combination strength and cardiovascular training, sometimes even within the same movement.
Another reason you might use a kettlebell is their recent popularity. While the kettlebell has a long (maybe even ancient) history, they have recently become commonly known and used. As of now, there is a sizeable number of resources you can find to help you get started with the kettlebell and a growing number of people who are eager to learn and teach how to use a kettlebell to promote wellness.
Lastly, and maybe most importantly, the kettlebell is compact, and convenient. A single kettlebell, when used to its maximum potential can take the place of a rack of dumbbells. Many of the exercises that you would perform with traditional dumbbells can be easily done with a kettlebell instead, and there are a whole lot of exercises you can do with a kettlebell that just wouldn't work with a dumbbell.
History
The Russian girya (ги́ря, a loanword from Persian غران giran "heavy") was a type of metal weight, primarily used to weigh crops, in the 18th century. The use of such weights by circus strongmen is recorded for the 19th century. They began to be used for recreational and competition strength athletics in Russia and Europe in the late 19th century. The birth of competitive kettlebell lifting or girevoy sport (гиревой спорт) is dated to 1885, with the foundation of the founding year of the "Circle for Amateur Athlethics" (Кружок любителей атлетики).
Russian kettlebells (Russian: ги́ри giri, singular ги́ря girya) are traditionally measured in weight by pood, corresponding to 16.38 kilograms (36.1 lb). The English term kettle bell has been in use since the early 20th century.
Similar weights used in Classical Greece were the haltere, comparable to the modern kettlebell in terms of movements. Another comparable instrument was used by Shaolin monks in China.