 Water provides a controllable environment for reeducation of weak muscles and skill development for neurological and neuromuscular impairment, acute orthopedic or neuromuscular injury, rheumatological disease, or recovery from recent surgery.Various properties of water contribute to therapeutic effects, including the ability to use water for resistance in place of gravity or weights; thermal stability that permits maintenance of near-constant temperature; hydrostatic pressure that supports and stabilizes, and that influences heart and lung function; buoyancy that permits flotation and reduces the effects of gravity; and turbulence and wave propagation that allow gentle manipulation and movement.The use of water for therapeutic purposes first dates back to 2400 B.C.