PHOTO CAPTION: Aquatic therapy can help effectively manage chronic pain, increase activity tolerance, and improve quality of life.

By Pamela Lofgren, DPT, and Arantxa Boby, PT, DPT, MSc, OMPT

Water has great healing capacity. Water offers a unique environment thanks to its hydrodynamic and thermal properties, allowing for many activities that cannot be achieved on land. Originally developed by fluid mechanics engineer James McMillan in the 1940s and 1950s, the aquatic therapy method that is used by physical therapists today focuses on helping patients develop balance and core stability. In the United States, hydrotherapy usually refers to a hospital-based physical therapy program for patients with wounds or other acute injuries, while aquatic therapy begins with an individual exam and assessment and is usually in an outpatient setting.

Properties of Water

Water’s five properties make it a productive setting for treating chronic pain, healing from injuries, and recovering from surgery.

1) Buoyancy: This property can provide support and/or resistance to body structures. Depending on the exercise done in the water, buoyance can assist or resist the movement. Buoyancy counterbalances gravity and supports the body that decreases weight-bearing through the extremities and spine.
2) Hydrostatic pressure: Pascal’s law states, “fluid pressure is exerted equally on all surfaces of an immersed body at rest at a given depth.” Hydrostatic pressure increases as the body submerges and at deeper depths can act like a compression garment. Thus, aquatic environments can help decrease blood pooling in the lymphatic and venous systems and decrease edema in a joint. Hydrostatic pressure can also provide intercostal muscle strengthening with taking deep breaths while submerged to chest level.
3) Viscosity: Friction that exists between molecules that cause resistance to water flow. As a body part moves faster in the water, it increases the resistance of the water against the object moving. Viscosity can assist with proprioceptive awareness in the water to help with balance and postural exercises.
4) Flow and drag: The streamlined flow (uninterrupted flow) of the water assists a person moving in the water, while turbulent flow (when the water undergoes irregular fluctuations or mixing) resists their movement in the water. Surface tension — tension of the surface film of the water caused by the attraction of the particles in the surface layer by the bulk of the water — can be used as a resistance tool with exercises in the water.
5) Refraction: The change in the direction of a wave due to change in the speed. Refraction can help challenge exercises in the water related to gait, balance, and posturing due to eliminating visual cues.

Aquatic Therapy for Pain Management

These properties make aquatic therapy an exciting treatment form for pain management. Opioids are popularly prescribed for pain, though Coussens et al1 state opioid overuse can lead to severe debilitation, loss of quality of life and even death, making it a major public health issue. There is an urgent need for collaboration between different specialties in health care to address this crisis, and physical therapists can make a huge contribution by means of providing non-addictive treatment options. In light of the ongoing opioid crisis, forms of treatment like aquatic therapy are more relevant than ever before, and it is important to review the literature to build evidence-based practice in this area.

Many patients seen in outpatient physical therapy suffer from chronic pain conditions, which may limit their quality of life and activity tolerance. Common conditions include chronic low back pain, fibromyalgia, osteoarthritis, related-joint pain, and even general deconditioning due to multiple comorbidities. Many patients suffering from chronic joint pain may not be candidates for surgical procedures, and conditions like fibromyalgia still don’t have a cure. These patients are often referred to physical therapy to build strength, but are not able to tolerate the exercise program due to high pain levels, which either leads to noncompliance with the plan of care or increased use of pain medication. In such cases, aquatic therapy may provide a suitable solution where patients are able to tolerate exercises better because of water’s properties outlined above, while the regulated temperature in most pools provides additional pain-relief benefits.

For instance, a meta-analysis by Batterham et al2 compared land and aquatic exercise for people with hip or knee arthritis on function, mobility and other health outcomes. They found that when land exercises were too painful or hard for these patients, aquatic therapy was an excellent alternative for exercise. Aquatic therapy can be an excellent form of maintenance therapy to preserve existing joint motion and muscle function without aggravating pain levels.

Supporting Evidence

Literature in the area of aquatic therapy as a therapeutic tool and found evidence for its role in pain management. Numerous studies point to aquatic therapy’s ability to relieve pain, recover from injuries and surgeries, and help improve overall quality of life. The articles below were assessed keeping in mind various relevant pathologies and diagnoses that are generalized as well as those specific to certain areas in the body.

Baena-Beato et al3 conducted a study on 49 sedentary individuals suffering from low back pain. The subjects underwent an intensive program of aquatic therapy five times a week for a 2-month period, and it was found that the active group had a significant improvement in their low back pain levels, measured through the visual analog scale, and their disability levels, assessed through an Oswestry Disability Index. In addition to this, their overall quality of life and body composition were also reported to have improved.

Similarly, in a randomized controlled trial of aquatic therapy for the treatment of fibromyalgia in unfit women, Munguia-Izquierdo et al4 found that a frequency of aquatic therapy three times a week for 16 weeks in a warm therapy pool improved most of the patients’ symptoms. As well, the patients were very motivated to continue with their exercise program on their own.

Bidonde et al5 assessed the benefits and harms of aquatic therapy in fibromyalgia patients by performing a systematic review. The 16 studies selected were randomized controlled trials of which nine compared the aquatic exercise group to a control group, five studies compared aquatic program to a land-based exercise program, and two compared different aquatic therapy groups. The most significant results were found in the studies that compared the aquatic therapy with the control group. All the outcome measures showed significant improvements in factors including pain levels, stiffness, muscle strength, cardiovascular function and physical function. The other studies did not show significant changes. However, no adverse effects were noted in any of the aquatic exercise groups.

Bartels et al6 assessed the benefits of aquatic therapy in patients with chronic knee and hip osteoarthritis and found moderate evidence of short-term, clinically relevant benefits especially regarding pain and disability levels. This indicates that patients who may be trying to delay surgical interventions might be able to benefit from aquatic therapy in the meantime.

A limitation noted in most studies is the lack of consistency in the protocols used for aquatic therapy. This makes it difficult to compare different studies in order to draw common conclusions. Further research that compares specific protocols in aquatic therapy will be of benefit to physical therapists in order to plan effective treatment programs moving forward.

Water Therapy at Any Size

Clinics considering bringing aquatic therapy on-site can select from large in-ground pools to small-footprint models such as the HydroWorx 300, offered by Middletown, Pa-headquartered HydroWorx. The 300 is a modular unit that has a variable-speed underwater treadmill, adjustable water level, resistance jet, and can be used by two people simultaneously. The HydroWorx 350 has simnilar features to the HydroWorx 300 and offer 6 inches more of depth, 7 inches more of treadmill surface, and a stronger resistance jet. HydroWorx’s new EVO is a 30-square-foot self-contained system designed to fit a 3-foot by 9-foot space and fit through a 36-inch door.

Hudson Aquatic Systems LLC, Angola, Ind, offers the AquaFit underwater treadmill systems as a modular aquatic therapy exercise chamber solution. Features for this compact unit include an adjustable treadmill and adjustable water depths.

Both HydroWorx and Hudson Aquatic Systems manufacture large commercial pools suitable for aquatic therapy. Hudson’s line of AquaPools can accommodate multiple users and features multiple depths and viewing windows where underwater activities can be monitored. The HydroWorx 500 is a larger pool that can accommodate up to three people at once and features underwater cameras and the ability to monitor and record all functions of the pool.

The HydroWorx 500 also has variable depth and features a pool-mounted display system in addition to a variable-speed underwater treadmill. The HydroWorx 2000 Series pools accommodate up to four people at a time, and its functions can be controlled by a handheld water-resistant remote. The HydroWorx 2000 includes a moveable floor in addition to many of the features found on the HydroWorx 500.

Precautions and Contraindications

As beneficial as aquatic therapy is, there are also some precautions and contraindications for utilizing this type of physical therapy to treat patients. Precautions of aquatic therapy are fear of water, small open wounds/lines, seizures, neurological disorders, and cardiac dysfunction. Contraindications are open wound/infection, active rashes, severe peripheral vascular disease, uncontrolled seizures, urinary infections, infectious diseases, severe high or low blood pressure, light-headedness, cardiac failure or unstable angina, danger of bleeding or hemorrhaging, fever, lower-extremity sensory deficit, severe kidney disease, respiratory dysfunction, uncontrolled bowel or bladder, senility, and menstrual cycle. Patients should consult with their physicians before engaging in aquatic therapy.

Therapists should check a patient’s insurance before sending them in the pool. Most insurances, including Medicare and Medicaid, do accept aquatic therapy, but depending on the state, a few commercial insurance companies do not provide coverage.

Aquatic therapy has the potential to be an effective treatment in improving quality of life, increasing activity tolerance, and managing pain for patients suffering from chronic pain who otherwise might have to depend on medications. It is an effective approach that can continue to help patients feel their best through greater awareness about its benefits and more expansive insurance coverage. PTP

Pamela Lofgren, DPT, is a clinic director and physical therapist with ATI Physical Therapy in New Berlin, Wisconsin. She has been an outpatient therapist for 20 years with specialties in women’s health, aquatic therapy, dry needling, Graston Technique and spinal/pelvic rehabilitation. Lofgren graduated with her Doctor of Physical Therapy degree from Massachusetts General Hospital through Harvard College.

Arantxa Boby, PT, DPT, MSc, OMPT, is a clinic director with ATI Physical Therapy in Keego Harbor, Michigan. She earned her Master of Exercise Science and Kinesiology degree and Doctor of Physical Therapy degree from Oakland University. For more information, contact [email protected].


  1. Coussens NP, Sittampalam GS, Jonson SG, et al. The opioid crisis and the future of addiction and pain therapeutics. J Pharmacol Exp Ther. 2019;371(2): 396-408. DOI: 10.1124/jpet.119.259408
  2. Batterham SI, Heywood S, Keating JL. Systematic review and meta-analysis comparing land and aquatic exercise for people with hip or knee arthritis on function, mobility and other health outcomes. BMC Musculoskelet Disord. 2011;12:123.
  3. Baena-Beato PÁ, Artero EG, Arroyo-Morales M, et al. Aquatic therapy improves pain, disability, quality of life, body composition and fitness in sedentary adults with chronic low back pain. A controlled clinical trial. Clinical Rehabil. 2014;28(4): 350-60. DOI: 10.1177/0269215513504943
  4. 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(12):2250-2257.
  5. Bidonde J, Busch AJ, Webber SC, et al. Aquatic exercise training for fibromyalgia. Cochrane Database Syst Rev. 2014 Oct 28;(10:CD011336. DOI: 10.1002/14651858.CD011336
  6. Bartels EM, Juhl CB, Christensen R, et al. Aquatic exercise for the treatment of knee and hip osteoarthritis. Cochrane Database Syst Rev. 2016 March 23;3:CD005523. DOI: 10.1002/14651858.CD005523.pub3

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