US Patent 11285352 Method of exercise using two-handled container partially filled with liquid

A method of exercise includes partially filling (not more than 70% full) a symmetrical hollow body of an exercise device with water, grasping a pair of opposed handles attached to the hollow body, positioning the device at a height and orientation for a first set of motions, and rapidly oscillating the device at a frequency (≥2 HZ) to transform the water from a static state into a dynamic state in which the center of mass oscillates and hydrodynamic forces arise. Optionally, an additive such as viscosity enhancer or beads for audible effect may be introduced in the water.