Present day underwater therapy embodies three of the basic principles of physical medicine: (1) hydrotherapy, (2) therapeutic exercise based on a thorough knowledge of muscle anatomy and action and (3) massage. Regardless of the type of water or apparatus used and of the disease to be treated, these principles hold and their application is based on definite physiologic responses of the body to their use.1 By giving therapeutic exercise and massage in water, certain mechanical advantages are obtained which increase the range of physiologic effect and permit a more accurate and satisfactory exercise dosage to be given.2 There is nothing "specific" in this form of therapy. Results obtained from using it are directly proportional to the diagnostic acumen of the physician and the skill and training of the physical therapist giving the treatment.
The use of water, exercise and massage in the treatment of disease is as old
SMITH EM, CROOK BL. UNDERWATER THERAPY AT SPAS. JAMA. 1944;124(8):505-509. doi:10.1001/jama.1944.62850080004010