Onnit: The worldâs first-ever truly holistic kettlebell program transformation plan. Kettlebells provide the challenge of off-set loading, meaning that the weightâs center of gravity is set off from the handle. That makes it more challenging to balance and control, and youâll need to call on every muscle in your body (particularly your core) to perform your exercises.The kettlebell provides a more user-friendly means of performing classic strength-, muscle-, and power-building exercises, such as the clean and snatch, which many people canât do safely with a barbell. It lends itself perfectly to flowing movement, building stability and mobility that carries over to athleticsâas well as the game of lifeâseamlessly.