Aquatic Therapy – Scientific Foundations and Clinical Rehabilitation Applications
Clinical Review by Bruce E. Becker, MD, MS
The aquatic environment has broad rehabilitative potential, extending from the treatment of acute injuries through health maintenance in the face of chronic diseases, yet it remains an underused modality. There is an extensive research base supporting aquatic therapy, both within the basic science literature and clinical literature.
This article describes the many physiologic changes that occur during immersion as applied to a range of common rehabilitative issues and problems. Because of its wide margin of therapeutic safety and clinical adaptability, aquatic therapy is a very useful tool in the rehabilitative toolbox.
Through a better understanding of the applied physiology, the practitioner may structure appropriate therapeutic programs for a diverse patient population.
Since the earliest recorded history, water has always been believed to promote healing and has therefore been widely used in the management of medical ailments. Through observation and centuries of trial and error, and scientific methodology, traditions of healing through aquatic treatments have evolved.
This review will detail the current scientific understanding of the many physiologic changes that occur during aquatic immersion. Aquatic immersion has profound biological effects, extending across essentially all homeostatic systems. These effects are both immediate and delayed and allow water to be used with therapeutic efficacy for a great variety of rehabilitative problems.
Aquatic therapies are beneficial in the management of patients with musculoskeletal problems, neurological problems, cardiopulmonary pathology, and other conditions. In addition, the margin of therapeutic safety is wider than that of almost any other treatment milieu.
Knowledge of these biological effects can aid the skilled rehabilitative clinician to create an optimal treatment plan, through appropriate modification of aquatic activities, immersion temperatures, and treatment duration.
Historically, the field of Physical Medicine viewed hydrotherapy as a central treatment methodology. In 1911, Charles Leroy Lowman, the founder of the Orthopaedic Hospital in Los Angeles, which later became Rancho Los Amigos, began using therapeutic tubs to treat spastic patients and those with cerebral palsy after a visit to the Spaulding School for Crippled Children in Chicago, where he observed paralyzed patients exercising in a wooden tank. On returning to California, he transformed the hospital’s lily pond into 2 therapeutic pools
At Warm Springs, Georgia, Leroy Hubbard developed his famous tank, and in 1924, Warm Springs received its most famous aquatic patient, Franklin D. Roosevelt. A wealth of information, research, and articles on spa therapy and pool treatments appeared in professional journals during the 1930s.
At Hot Springs, Arkansas, a warm swimming pool was installed for special underwater physical therapy exercises and pool therapy treatments with chronic arthritic patients .
By 1937, Dr. Charles Leroy Lowman published his Technique of Underwater Gymnastics: A Study in Practical Application, in which he detailed aquatic therapy methods for specific underwater exercises that “carefully regulated dosage, character, frequency, and duration for remedying bodily deformities and restoring muscle function” .
During the 1950s, the National Foundation for Infantile Paralysis supported the corrective swimming pools, and hydrogymnastics of Charles L. Lowman and the therapeutic use of pools and tanks for the treatment of poliomyelitis.
In 1962, Dr. Sidney Licht and a group of physiatrists organized the American Society of Medical Hydrology and Climatology, which historically met at the annual meeting of the American Academy of Physical Medicine and Rehabilitation.
THE PHYSICAL PRINCIPLES OF WATER
Nearly all the biological effects of immersion are related to the fundamental principles of hydrodynamics. These principles should be understood to make the medical application process more rational. The essential physical properties of water that effects physiologic change are density and specific gravity, hydrostatic pressure, buoyancy, viscosity, and thermodynamics.
This thermal conductive property, in combination with the high specific heat of water, makes the use of water in rehabilitation very versatile because water retains heat or cold while delivering it easily to the immersed body part. Water may be used therapeutically over a wide range of temperatures. Cold plunge tanks are often used in athletic training at temperatures of 10°–15°C to produce a decrease in muscle pain and speed recovery from overuse injury, although there are some contradictory studies regarding this [6-8]. Most public and competitive pools operate in the range of 27°–29°C, which is often too cool for general rehabilitative populations, because these populations are usually less active in the water. Typical therapy pools operate in the range of 33.5°–35.5°C, temperatures that permit lengthy immersion durations and exercise activities sufficient to produce therapeutic effects without chilling or overheating. Hot tubs are usually maintained at 37.5°–41°C, although the latter temperature is rarely comfortable for more than a few minutes, and even the lower typical temperature does not allow for active exercise.
Heat transfer begins immediately on immersion, and as the heat capacity of the human body is less than that of water (0.83 versus 1.00), the body equilibrates faster than water does.
Applications in Cardiovascular and Cardiopulmonary Rehabilitation
Applications in Respiratory and Athletic Rehabilitation
Applications in Musculoskeletal Rehabilitation
Applications in Athletic Training
Applications in Geriatric and Osteoporosis Rehabilitation
Relevant Thermoregulatory Effects and Pregnancy
Pain and Psychiatric Rehabilitation
Aquatic Activities Appropriate to Rehabilitations Issues
Figure 3 details techniques appropriate for various populations seen in physiatry. As research demonstrates, immersing the body in water produces many physiologic effects that have been used therapeutically over centuries of medical history.
Aquatic exercise and rehabilitation remains vastly underused despite its recent increase in popularity. The health benefits of aquatic exercise have been shown to equal or surpass other forms of exercise including walking and running in studies of the Cooper Clinic database of more than 30,000 men and women [171,199]. These studies assessed overall health benefits of aquatic exercise with land-based walking and running, finding health effects comparable to both land activities, with the potential added value of aquatic activities broader range of clinical applicability in specific populations. Review of the Cooper Clinic database of more than 40,000 men showed exercise swimmers to have less than half the mortality risk of sedentary men, and, surprisingly, approximately half the mortality risk of exercise walkers and runners . All these effects are good reasons to use the aquatic environment in training and rehabilitation.
Aquatic facilities are widely available, and public acceptance is already high, so there are tremendous potential public health benefits to be achieved through programs targeted at the most costly chronic diseases: hypertension, cardiovascular disease, arthritis, and other musculoskeletal pathology, obesity, and deconditioning. Aquatic programs for achieving fitness and restoring function may be designed for a broad range of individuals through an understanding of the fundamental principles of aquatic physics and the application of those principles to human physiology. There are unique attributes to aquatic therapy that seem to both preserve and protect health and longevity.
More on Aquatic Therapy Applications
-  deVierville J. A history of aquatic rehabilitation. In: Cole A, Becker B, eds. Comprehensive Aquatic Rehabilitation. 2nd ed. Philadelphia PA: Butterworth-Heinemann; 2004:1-18.
-  Smith E. Hydrotherapy in arthritis: Underwater therapy applied to chronic atrophic arthritis. Paper presented at: 14th Annual Session of the American Congress of Physical Therapy; September 11, 1935, 1935; Kansas City, MO.
-  Lowman CL. Technique of Underwater Gymnastics: A Study in Practical Application. Los Angeles: American Publications; 1937.
-  Bloomfield J, Fricker P, Fitch K. Textbook of Science and Medicine in Sport. Champaign IL: Human Kinetics Books; 1992.
-  Poyhonen T, Keskinen KL, Hautala A, Malkia E. Determination of hydrodynamic drag forces and drag coefficients on human leg/foot model during knee exercise. Clin Biomech (Bristol, Avon) 2000;15: 256-260.
-  Chase NL, Sui X, Blair SN. Comparison of the health aspects of swimming with other types of physical activity and sedentary lifestyle habits. Int J Aquatic Res Edu 2008;2:151-16
-  Chase NL, Sui X, Blair SN. Swimming and all-cause mortality risk compared with running, walking and sedentary habits in men. Int J Aquatic Res Educ 2008;2:213-223.
-  Chase NL, Sui X, Blair SN. Comparison of the health aspects of swimming with other types of physical activity and sedentary lifestyle. Int J Aquatic Res Educ 2008;2:151-161.
© 2009 by the American Academy of Physical Medicine and Rehabilitation, Vol. 1, 859-872, September 2009, DOI: 10.1016/j.pmrj.2009.05.017; PM&R 1934-1482/09/$36.00, Printed in U.S.A.