The kettlebell is a cast iron or cast steel ball with a handle attached to the top (resembling a cannonball with a handle). It is used to perform many types of exercises, including ballistic exercises that combine cardiovascular, strength and flexibility training. They are also the primary equipment used in the weight lifting sport of kettlebell lifting
The Russian girya (ги́ря, plural ги́ри giri) 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 founding of the "Circle for Amateur Athletics" (Кружок любителей атлетики). Russian 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.
By their nature, typical kettlebell exercises build strength and endurance, particularly in the lower back, legs, and shoulders, and increase grip strength. The basic movements, such as the swing, snatch, and the clean and jerk, engage the entire body at once, and in a way that mimics real world activities such as shoveling or farm work.
Unlike the exercises with dumbbells or barbells, kettlebell exercises involve large numbers of repetitions in the sport, and can also involve large reps in normal training. Kettlebell exercises are in their nature holistic; therefore they work several muscles simultaneously and may be repeated continuously for several minutes or with short breaks. This combination makes the exercise partially aerobic and more similar to high-intensity interval training rather than to traditional weight lifting. In a 2010 study, kettlebell enthusiasts performing a 20-minute snatch workout were measured to burn, on average, 13.6 calories/minute aerobically and 6.6 calories/minute anaerobically during the entire workout - "equivalent to running a 6-minute mile pace". When training with high repetitions, kettlebell progression should start out slowly to build muscle endurance, support the joints and prevent injury.
Like movements performed with any exercise tool, they can be dangerous to those who have back or shoulder problems, or a weak core, when performed without proper education and progression. However, if done properly, they are very beneficial to health. They can offer improved mobility, range of motion, agility, cardio vascular endurance, mental toughness and increased strength