By Karolyn A. Bauer, MSPT, ATRIC
Wide Open Options As an aquatic physical therapist, I am often asked what types of patients are appropriate for aquatic therapy. My answer is many but, of course, the answer is not that simple. Patients with a variety of ailments can benefit from aquatic therapy at some time during their rehabilitation. Strength Training Water is an excellent medium for performing strength training because it provides resistance in all three dimensions.1 In particular, rehabilitation of the shoulder and hip joints can be performed safely and efficiently in the water using early buoyancy-assisted movement and later the resistance provided by the viscosity of the water. Early strengthening can be carried out safely because muscle contractions against the resistance of the water are isokinetic. When the patient decreases force output because of pain or fatigue, the resistance provided by the water decreases proportionally,2 thus preventing injury and overuse. Viscosity provides resistance in every direction during strength training in the water. Unlike gravity, which only resists upward forces, viscosity, the friction between the different layers of fluid,3 resists movements in every plane. Therefore, water is capable of simultaneously resisting all three planes of movement in proprioceptive neuromuscular facilitation (PNF) patterns. The amount of resistance the water provides can be increased by increasing the speed of the movement or by increasing the surface area of the object moving through the water.3 Starting patients with gentle, buoyancy-assisted, active range of motion exercises in the water can prevent secondary conditions such as adhesive capsulitis, capsular patterns, and the development of reverse scapulo-humeral rhythm. Patients can be started on straight plane strengthening exercises and then progress to PNF patterns. When overhead activities become appropriate, the patient can use a mask and snorkel to continue PNF training in the prone position in the water. For added resistance, first ask the patient to try to double the speed of movement. If the patient is able to successfully increase the speed of movement and maintain good form with this added resistance, equipment can be used to increase surface area. Webbed gloves on the hands or fins on the feet enlarge surface area and therefore increase resistance. Because the water resists movements in all three dimensions, complicated functional tasks such as pitching a baseball can be effectively resisted throughout the entire arc of movement without modifying the motor pattern. Cables, despite the use of pulleys to redirect the force of gravity, and other resistive equipment such as resistive bands, can provide resistance only to linear motor patterns. Both primary balance disorders and lower extremity injuries resulting in secondary balance disorders can be effectively rehabilitated using turbulence in the buoyant, viscous environment of the water. Buoyancy provides an upward force that counters gravity and prevents injuries associated with falls during balance training. The viscosity of the water also slows a fall, allowing increased time for righting reactions and stepping strategies.2 Turbulence can be used to provide perturbations during balance retraining in the water.2 Unlike the therapist who pushes or pulls the patient in one direction at a time or who tosses a ball linearly to elicit a balance response, turbulence provides challenges to balance in all directions simultaneously. Turbulence refers to water that is moving irregularly. This irregularity causes the formation of eddies, which are circular currents. Therefore, turbulence creates a destabilizing effect in many directions at one time.3 Patients start by learning to resist the turbulence they create by their own movements in the water. For example, there is a slight forward weight shift required when performing a calf raise that starts the water flowing in that direction. The patient must resist the forward flow of water to stop her forward weight shift and prevent a fall. Conversely, when returning to a flat-footed position, the patient must resist the back ward flow of water so she does not fall backward. Later, externally created turbulence can be added to perturb the patient’s balance. By walking past the patient as she performs calf raises, you create a wake that challenges her balance further. You can also use your hands or a kickboard to create more turbulent waves in the direction of the patient. Spinal Injuries The properties of water combine to elicit different neuromuscular responses at different stages of rehabilitation. Buoyancy, viscosity, and turbulence interact to decrease unwanted muscular guarding, allow contraction of targeted muscles, and promote activation of stabilizers. Overall, the water makes compensatory motor patterns unnecessary and thus encourages optimal patterns to emerge.4,5 These effects are particularly useful for all stages of rehabilitation of spinal injuries. Throughout the progression from early pain reduction and return to movement, to progressive lumbar stabilization, and later for advanced functional retraining, the water provides a unique environment for rehabilitation. Furthermore, because of water’s soothing effect, patients often prefer aquatic therapy to land-based rehabilitation, thus increasing compliance. In the acute stage, buoyancy reduces the painful effects of gravity on the injured spine and supports the limbs to make simple movements in the water easy and pain-free.2 This early mobilization prevents the onset of adaptive muscle shortening and emphasizes optimal motor patterns. In addition, if the water is warm, this promotes relaxation of guarding musculature. Even before the initial gains have been fully realized, the patient can begin a gentle spinal stabilization program. As the limbs move more quickly and forcefully into the viscosity of the water, the need for core stability to support those movements becomes evident. For example, as the patient lifts the right leg forward, the body counterrotates to the right. When instructed to prevent this counterrotation, the patient recruits the deep stabilizers of the spine to create the desired stability. Both arm and leg movements can be used to train the thoracic and lumbar stabilizers while upper extremity exercises promote the desired effect in the cervical spine. To progress lumbar stabilization training, resistance can be added to limb movements by increasing lever arm length, speed, and surface area.3 The added resistance acts to increase the work of the spinal stabilizers. Turbulence can be added to create an unstable environment in order to train the reaction times of the stabilizers in the spine as well as in the stance leg. To further train the musculature of the trunk, the floor can be removed as a reference point and lumbar stabilization training can continue in deep water. When suspended vertically in deep water using a buoyant belt and some type of handheld buoyant equipment, the patient can continue exercises similar to those in shallow water. In deep water, the stability provided by the floor is absent and the patient must begin the movement by stabilizing in the trunk. For example, the same right forward leg lift will initially produce left hip extension in the deep water. By encouraging the patient to prevent the reaction in the left leg, additional trunk stabilizers are recruited.6 Once this unsupported stabilization is mastered, increased speed and surface area can again be employed to increase the resistance. Buoyant cuffs added to the ankles also increase the difficulty of these exercises, but keep in mind that buoyancy only resists downward forces while equipment such as fins resists movements three-dimensionally. Facing the Pressure Immersion in the aquatic environment subjects the body to a compressive force—hydrostatic pressure—which can be beneficial in strengthening respiratory muscles and reducing edema. However, in order to utilize aquatic therapy safely and effectively, it is particularly important for clinicians to understand the physiological effects of hydrostatic pressure. Hydrostatic pressure exerts about 15 pounds of pressure on all areas of a submerged body.7 This is experienced as a resistive force to the expansion of the rib cage during breathing. Patients with compromised respiratory ability do very well training primary and secondary respiratory muscles against the hydrostatic pressure of the water. However, caution should be used when patients with a vital capacity of less than 1 L are immersed in water because the added pressure of the water can compromise respiratory function.8 If desired, the hydrostatic effects of water on the respiratory system can be significantly reduced by treating patients in supine, using techniques such as Bad Ragaz, Watsu, and Jahara. Hydrostatic pressure is also responsible for the centralization of blood volume, which in turn causes a decrease of edema in the lower extremities.3 Many patients with ankle injuries or postoperative knee conditions also have swelling in the lower leg. Treatment of these lower extremity injuries in the water is efficient because the edema is addressed during the entire length of the treatment while the patient and therapist focus on meeting other goals. It is important to understand that, as blood is shunted from the lower extremities into the trunk, it has an impact on the cardiovascular system. The enhanced venous return results in increased heart volume and central venous pressure as well as decreased heart rate.9 Relatively speaking, however, the change in heart volume is approximately equal to the effect of assuming a supine posture from a standing posture. The change in blood pressure is less than would be typically seen with moderate exercise. The overall change in heart rate depends on the temperature of the water and the amount of exercise, if any.10,11 When considering aquatic therapy for a patient with a medical background that includes cardiac, pulmonary, or renal disease, it is especially important to understand the physiological effects of hydrostatic pressure. For example, the centralization of blood volume increases the stress on the renal system, and is responsible for the increased production of urine during and following immersion. This effect is accompanied by the increased excretion of potassium and sodium.12 Normally, these effects are nothing more than inconvenient, but if this added stress would be detrimental to a patient with renal disease, then aquatic therapy would be contraindicated. Editor’s Note: The references are posted with the online version of this story at www.rehabpub.com. Karolyn A. Bauer, MSPT, ATRIC, is the aquatic program manager, Long Island Orthopaedic and Sports Physical Therapy, PC, Douglaston, NY, and the current Membership Chair of the Aquatic Physical Therapy Section of the American Physical Therapy Association. References 1. Kolb ME. Principles of underwater exercise. Physical Therapy Review. 1957;37:361-364. 2. Schoedinger P. Principles of aquatic therapy. In: Aquatic Therapy Symposium Program Book. Washington, DC: Aquatic Therapy and Rehabilitation Institute; 1996:H25-H31. 3. Serway RA, Faughn JS. College Physics. 4th ed. New York: Harcourt Brace College Publishers; 1995: 267. 4. Napoletan Craig J. Orthopedic rehabilitation of the lower extremity. Biomechanics. 1996;3:23-25. 5. McNeal RL. Aquatic rehabilitation of clients with rheumatic disease. In: Ruoti RG, Morris DM, Cole AJ, eds. Aquatic Rehabilitation. New York: Lippincott; 1997:195-210. 6. Burdenko IN. The Burdenko Method— water and land program. In: Aquatic Therapy Symposium Program Book. Washington, DC: Aquatic Therapy and Rehabilitation Institute; 1998:H65-H70. 7. Golland A. Basic hydrotherapy. Physiotherapy. 1981;67:258-262. 8. Garvey LA. Spinal cord injury and aquatics. Clinical Management. 1991;11:21-24. 9. Risch WD, Koubenec HJ, Beckmann U, Lange S, Gauer OH. The effect of graded immersion on heart volume, central venous pressure, pulmonary blood distribution, and heart rate in man. Pflugers Arch. 1978;374:115-118. 10. Craig AB, Dvorak M. Thermal regulation during water immersion. J Appl Physiol. 1966;21:1577-1585. 11. Craig AB, Dvorak M. Thermal regulation of man exercising during water immersion. J Appl Physiol. 1968;25:28-35. 12. O’Hare J, Corrall RJM, Scott G, Walters G. Hemodilution during water immersion in man. Clin Sci. 1984;66:47.
