Aquatic-based therapy offers a healing medium and therapeutic components that can be customized to each patient’s needs.

Aquatic therapy is one of the many tools that therapists can use to assist in the healing process of musculoskeletal issues and conditions for patients of all ages, abilities, and diagnoses. This evidence-based treatment is generally designed to improve or sustain gait, muscle strength and endurance, balance, agility, function, coordination, flexibility, function, and body mechanics and posture. Therapists can specifically tailor treatment to each individual patient using underwater treadmills and orthotic or other assistive tools designed for water.

The aquatic environment allows injured muscles to use muscle memory without impact or bearing weight, and the water makes patients buoyant so they do not have to support as much of their own body weight. At OrthoCarolina, the therapy staff has introduced therapeutic techniques to the pool that have been effective among its patient population including manual therapy, injury rehabilitation, therapeutic exercise, functional training, and more.

Buoyancy and Water Properties

Buoyancy is defined as the upward thrust acting in the opposite direction of gravity.1 The physical properties of water can aid in a patient’s movement, decrease pain, and decrease inflammation. When it comes to aquatic therapy, buoyancy can decrease the amount of pressure and weight-bearing a patient may feel in the joints. If a female is submerged in water at the level of C7, the xiphoid process, or the ASIS, she will bear 8%, 28%, or 47%, respectively, of her weight. If a male is submerged at the same levels, he will bear 8%, 35%, and 54%, respectively, of his weight.1

“Joan,” an OrthoCarolina aquatic therapy patient recovering from a total knee replacement, noted a significant difference with her gait walking on one of the facility’s two underwater treadmills, when compared to regular land-based walking. She attributes her ability to regain normal walking and gait sequence to her aquatic therapy.

“I didn’t want to walk correctly out of the pool, because when I did, it would hurt. When I got on the treadmill in the pool, my therapist set it for about 25 minutes and I was able to walk in there without pain. The water makes you feel lighter. That doesn’t mean it’s easy, but it’s definitely a unique feeling,” Joan says.

The principles of buoyancy can be used in aquatic therapy exercise in three different ways. Buoyancy can assist in exercise, support a movement, or be used as resistance. For example, buoyancy-assisted exercises are any movements that occur in the direction toward the surface of the water. Buoyancy-supported exercise occurs perpendicular to the water surface, and resisted exercises occur against the upward thrust of buoyancy.1

Hydrostatic pressure is another property of water that is helpful in decreasing inflammation. Pascal’s law states that at any depth in water, the pressure from the water on an immersed object is the same from all directions.1 Because of this pressure, the cardiovascular system is assisted with reducing effusion and edema in the extremities.

Aquatic Therapy in Research

As aquatic therapy continues to grow in popularity, more is being written about the subject. One study looked at individuals diagnosed with either hip or knee osteoarthritis. The study was designed as a randomized controlled trial with 71 subjects. Each was assigned to a group that received either 6 weeks of aquatic physical therapy or no aquatic physical therapy. Pain levels, physical function, physical activity levels, quality of life, and muscle strength were used as outcome measurements. Subjects in the group who received aquatic physical therapy showed significant pain reduction, increased strength, improved physical function, and increased quality of life.2

Another study looked at the effects of aquatic physical therapy in women who had been diagnosed with fibromyalgia.3 Sixty women were divided into either a control group that received no treatment or were part of an aquatic therapy program three times a week for 16 weeks. The aquatic exercise was performed in chest-deep water. Outcome measurements that were used included tender point count, health status, sleep quality, physical function, and cognitive function.  The women who participated in the aquatic therapy program experienced significant results regarding decreased tender point count, improved sleep quality, improved cognitive function, and improved physical function.3

A third study took a different approach, with a control group that performed land exercise instead of no exercise.4 This study looked at individuals who were diagnosed with chronic low back pain, and divided 65 subjects into an aquatic therapy group and a land therapy group. Both groups experienced positive results regarding the modified Oswestry Disability Index and physical function, but the results did slightly favor the individuals who performed aquatic exercise.4

Cleanliness and Safety

All public pools should keep cleanliness and safety at a high priority, including aquatic therapy pools. At this facility, water temperature, room temperature, room humidity, and filter pressure gauges are checked daily to ensure the pool is functioning properly and the environment is safe for the patients to exercise. We also monitor chemical and pH levels and make adjustments daily. The pool is drained regularly to clean the internal surfaces and liner, and to refresh the water. We service the mechanisms of the pool annually to check the functionality of all the mechanical parts, as well as the treadmill.

Accessories Boost Functional Progress

The pools at OrthoCarolina are kept at a therapeutic temperature, between 88 and 90 degrees Fahrenheit. The warm water increases blood flow to the muscles, allowing for ease of movement. Underwater treadmills are also used to help normalize gait patterns, improve mobility, and increase walking tolerance. For patients who are further along in treatment, jets can provide resistance against walking or jogging on the treadmill, which aids in strengthening. In many cases, someone who may be able to walk only 5 to 10 minutes on land can easily walk for 30 minutes in the water. Pressure sensors in the treadmill allow therapists to analyze gait patterns of the patients, helping examine step length, evidence of toeing out, and adequate heel strike.

Underwater treadmills are appropriate for patients of all ages, surgeries, and abilities. Some patients may be recovering from total knee replacements with a primary goal of community ambulation. They want to be able to walk through the grocery store pain-free or walk in the park with their grandchildren. These patients also can practice their balance and improve proprioception by walking sideways or backward, which is important because not everything a person does in the course of daily activity occurs in a linear motion. Patients need to be agile enough to navigate regular obstacles that may present themselves in the environment. Other patients may include high-level athletes who want to return to sport as soon as it is safe to do so. With a physician’s permission, these athletes can begin a jogging program in the water, and sometimes begin an entire month before they would normally begin jogging on land. Water-based jogging is a safe option because of the decreased load placed on the joints. Once the athlete returns to running on land, the fluidity of a patient’s running form is much smoother because they have established normal mechanics in the water.

Pools are also appropriate for individuals with severe mobility impairments. Both aquatic therapy pools used at this facility are outfitted with hydraulic-powered lifts that have a 250-pound weight limit. The lifts are designed to allow a patient to sit in a chair, then be lifted up over the side of the pool, and gently lowered into the water. Patients may exit the pool by reversing the process. Patients with neurological diagnoses such as cerebral palsy or quadriplegia, or who have sustained strokes or spinal cord injury, can find relief with aquatic therapy. The goal of their aquatic therapy is not to fix the problem, but to treat their symptoms. The warmth of the water and assistance of buoyancy can help these patients decrease the tone in their muscles and begin to reestablish normal movement patterns.  Even if it is an unreasonable expectation for the patient to return to regular walking on land, there are great cardiovascular benefits for the patient to exercise in the upright position. And, if a patient is accustomed to sitting in a wheelchair all day, exercising in the upright position can help prevent muscle contractures through the hip and knee flexors.

Other accessories used with the facility’s pools include massager jets, useful for pain relief by stimulating blood flow and decreasing muscle tone in a taut muscle. Jets also can be used over a healed and closed incision to break down scar tissue formation. Because jets are portable, they can be used almost anywhere on the body. Additional assistive devices for use in the pools include weights that provide extra resistance when worn around the ankles or wrists, and a portable step to practice stair climbing. For patients who require more assistance in the water, a noodle offers support and more mobility.

Expanding the Benefits of Water

The versatility of aquatic therapy can help therapists offer therapeutic exercises and activity to an extremely wide range of patients. Accessories such as water dumbbells, noodles, flotation belts and vests, fins, and other tools help patients balance while in the pool and work against resistance, allowing them to accelerate therapy and participate in rehab activities earlier than they otherwise might on dry land.

And, just as important, in many cases the qualities of water can help patients begin and continue recovery with a lower level of pain. Whether treating an athlete in the prime of performance, or an older adult with a newly replaced hip who simply wants to walk again without pain, the healing properties of water offer therapists a valuable medium to help patients reach their goals. RM

Katie White, PT, DPT, OCS, is a physical therapist and clinical manager for OrthoCarolina in Charlotte, NC. She holds her Doctorate degree from Northeastern University, and is a Board Certified Clinical Specialist in Orthopedic Physical Therapy. She is also a Certified Strength and Conditioning Specialist, certified in Trigger Point Dry Needling, a certified Clinical Instructor, and a certified Kinesiotape practitioner. For more information, contact [email protected].


1. Thein J, Brody LT. Aquatic-based rehabilitation and training for the elite athlete. J Orthop Sports Phys Ther. 1998;29(1):32-41.

2. Hinman R, Heywood S, Day A. Aquatic physical therapy for hip and knee osteoarthritis: results of a single-blind randomized controlled trial. Phys Ther. 2007;87(1):32-43.

3. Munguia-Izquierdo D, Legaz-Arrese A. Assessment of the effects of aquatic therapy on global symptomatology in patients with fibromyalgia syndrome: a randomized controlled trial. Arch Phys Med Rehabil. 2008;89:2250-2257.

4. Dundar U, Solak O, Yigit I, Evcik D, Kavuncu V. Clinical effectiveness of aquatic exercise to treat chronic low back pain: a randomized controlled trial. Spine. 2009;34(14):1436-1440.