Hydrotherapy, the use of water to treat medical conditions, was first practiced by ancient Egyptians, and pools, saunas, baths, and tanks have historically been used to treat health concerns from arthritis to inulcers. Muscles have to work harder to move in water than on land, while the buoyancy of water reduces weight-bearing on bones, joints, and soft tissues, and the pressure exerted by water reduces swelling and inflammation.