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Definition/Description[edit | edit source]

Hydrotherapy Pool Exercises.jpg

Hydrotherapy (Aquatherapy) is any activity performed in water to assist in rehabilitation and recovery from eg. hard training or serious injury.[1][2] This therapy is been used for thousands of years.  It is a form of exercise in warm water and is a popular treatment for patients with neurologic and musculoskeletal conditions.[3] They enable an individual to practise performing movements that are coordinated and balanced. 

The goals of this therapy are muscle relaxation, strengthening, improving joint motion and reducing pain and in specific populations it helps improve muscle coordination and balance.[4][5] 

Physiotherapists often use the application of hydrotherapy in a rehabilitation setting. Water offers a secure, low-risk, and encouraging training environment, so older persons who want to engage in fitness programmes without having to worry about falling may find it beneficial [6]. As a result, client satisfaction and adherence to this form of exercise are often high. in addition, the therapeutic effects are often enhanced by the social setting of the sessions.

Hygiene and infection control needs to be closely monitored.

Physical properties of water[edit | edit source]

In common with other forms of matter, water has certain physical properties which include mass, weight, density, relative density, buoyancy, Hydrostatic pressure, surface tension, refraction and reflection.[7][8]

Of the physical laws of water that the physiotherapist should understand and apply when giving Aquatherapy, those of buoyancy and hydrostatic pressure are the most important.[7] Individuals' movements are slowed by the buoyant force of the water and the hydrostatic pressure. The viscosity of the water also provides extra sensory cues that help with the timing of muscle activation.[6] The lateral pressure exerted and the effect of buoyancy together will give the feeling of weightlessness.[7]

Buoyancy [edit | edit source]

Buoyancy is the force experienced as an upthrust which acts in the opposite direction to the force of gravity.[9] A body in water is therefore subjected to two opposing forces. When the weight of the floating body equals the weight of the liquid displaced, and the centres of buoyancy and gravity are in the same vertical line, the body is kept in stable equilibrium. [8] If the centres are not in the same vertical line the two forces acting on the body will cause it to roll over until it reaches a position of stable equilibrium.

Hydrostatic pressure [edit | edit source]

The molecules of a fluid thrust upon each part of the surface area of an immersed body. Pascal's law states that fluid pressure is exerted equally on all surface areas of an immersed body at rest at a given depth. Pressure increased with the density of the fluid and with its dept. This means that swelling will be reduced more easily if exercises are given well below the surface of the water where the increased pressure may be used.[8]

The hydrostatic pressure place on the outside of the body causes a decrease in Blood Pressure (BP) peripherally and an increase in the BP in and around the heart [9]. This can cause potential problems for eg Chronic Heart Failure (CHF) and Coronary Artery Disease CAD) clients and needs to be taken into consideration. The greater the depth, the higher the amount of change in the factors mentioned above. [10]

Surface Tension [edit | edit source]

Under tension, the fluid's surface functions as a membrane.  The fact that the tension is closely correlated with the object's size is the primary relevance of this feature. As a result, moving an object or body part above the water requires more effort than moving it below. This can be accomplished with the help of devices like floaters. [11]

Viscosity [edit | edit source]

Viscosity is the resistance to flow caused by friction between the molecules of a liquid. The viscosity of the liquid through which the movement is passing directly correlates to this resistance. Thus, the key finding of this feature is that resistance rises with increasing movement velocity and resistance also rises with increasing item or body part surface area.[11]

Physiological Effects[edit | edit source]

The physiological effects of water therapy combine those brought by the hot water of the pool with those of the exercises. The extent of the effects varies with the temperature of the water, the length of the treatment and the type and severity of the exercise.[7]

The physiological effects of exercise in water are similar to those of exercise on dry land. The blood supply to the working muscles is increased, heat is evolved with each chemical change occurring during the contraction, and the muscles temperature rises. There is an increased metabolism in the muscles resulting in a greater demand for oxygen and increased production of carbon dioxide. These changes augment the similar changes brought about by the heat of the water, and both contribute towards the final effect. The range of joint movement is either maintained or increased, and muscle power increases.[8]

During the immersion, the physiological effects are similar to those brought about by any other form of heat but less localized. A rise in body temperature is inevitable because the body gains heat from the water and from all the contracting muscles performing the exercises. As the skin becomes heated the superficial blood vessels dilate and the peripheral blood supply is increased. The blood flowing through these vessels is heated and by convection, the temperature of the underlying structures rises.[8]

The relatively mild heat of the water reduces the sensitivity of sensory nerve endings and the muscle tone will diminish when the muscles are warmed by the blood passing through them.[8]

Stretching and Strengthening[edit | edit source]

Therapeutic Effects [edit | edit source]

  • Relieve pain and muscle spasm [8]
  • To gain relaxation [8]
  • To maintain or increase the range of joint movement [7]
  • To re-educate paralyzed muscles[7]
  • To strengthen weak muscles and to develop their power and endurance.[8]
  • To encourage walking and other functional and recreational activities.[7]
  • To improve balance and coordination[12]
  • To improve circulation ( trophic condition of the skin ) [8]
  • To give the patient encouragement and confidence in carrying out his exercises, thereby improving his morale.[8]
  • The warmth of water blocks nociception by acting on thermal receptors and mechanoreceptors, thus influencing spinal segmental mechanisms.[3]
  • Warm water stimulates blood flow positively, which leads to muscle relaxation[3].
  • the hydrostatic effect may relieve pain by reducing peripheral oedema and by dampening the sympathetic nervous system activity.[3]

The study by Ahmed SAMHAN et al. suggests that monitored aquatic-based exercises effectively improve muscle strength, fatigue, and quality of life, and skin disease activity than land-based exercises in children with juvenile dermatomyositis[13].

Clinical Contraindications [edit | edit source]

Please note the following serious and absolute contraindications to prescribing hydrotherapy.[8][14]

Serious Contraindications Absolute Contraindications
  • Cardiovascular disease
  • cardiopulmonary disease
  • Diabetic
  • Balance disorder
  • History of CVA, Epilepsy
  • Incontinence
  • Labyrinthitis
  • a cold
  • Influenza
  • Fever
  • skin conditions
  • Chemical allergies (Chlorine)
  • Contagious diseases
  • Hepatitis
  • Tracheotomy
  • Urinary tract infection
  • Serious Epilepsy
  • Urinary incontinence
  • Open Wounds 
  • Recently Surgery 
  • Hydrophoby

Evidence[edit | edit source]

  • A Cochrane Review by Bartels et al (2016), examining the effectiveness of aquatherapy on hip and/or knee osteoarthritis showed that there was moderate quality evidence of “small, short term clinically relevant effect on patient reported pain, disability, and quality of life (QoL) in people with knee and hip osteoarthritis (OA) after completion of an aquatic exercise program”. [15]
  • A systematic review and meta-analysis by Heywood et al (2016) which analysed lower limb strength in musculoskeletal conditions, which include hip or knee osteoarthritis, rheumatoid arthritis, post knee arthroplasty or ACL reconstruction, fibromyalgia and osteoporosis. It compared more than 6 weeks of aquatic therapy to land based exercise or no exercise, and found that there was low-very low quality of evidence, which indicated poor evidence. This is probably due to “inadequate application of resistance in water” to elicit gains in strength. [16]
  • A study by McNamara et al (2013) explored the effect of water-based exercise training for 4 weeks to no training, on COPD. With different walking tests, such as the 6MWD, Incremental Shuttle Walk Test, and Endurance Shuttle Walk Test, it was found that “There is limited quality evidence that water based exercise training is safe and improves exercise capacity and quality of life in people with COPD immediately after training”. [17]
  • A systematic review and meta-analysis by Depiazzi J (2018) explored the effect of HIIT on aerobic performance, strength and body composition in a non-athletic population, which found that individuals that carried out an aquatic HIIT program showed a greater aerobic performance (SMD 0.69 (95% CI 0.39 0.98); I 2 = 0%; n = 191) and lower limb muscle strength (SMD 0.30 (95% CI 0.04 0.56); I 2 = 0%; n = 237). [18]

This shows mixed views on the condition and type of training and population pursuing aquatic therapy.

Difference Between Aquatic Exercise and Balneotherapy[edit | edit source]

Balneotherapy is hydrotherapy but without exercise and is also called “Spa therapy”. It is frequently used in alternative medicine as a disease cure and is very popular for treatment of all types of arthritis.[3]

There are not many studies that describe the difference in therapeutic effects between aquatic exercise and balneotherapy without exercise. In the following review article, ‘Effectiveness of Aquatic Exercise and Balneotherapy’, results show that Aquatic exercise had a small significant effect on pain reduction, improvement of function, quality of life and mental health. Compared to balneotherapy, an exercise in water is more effective for the treatment of musculoskeletal diseases than passive immersion. There are no long-term effects, so to keep the disease stable, it is necessary to frequently participate in water exercises.
It is not clear what exactly the effect is of balneotherapy in musculoskeletal diseases because the studies involving this subject have poor methodological quality, which makes it difficult to determine the individual effect in this therapy.[4]

Examples of Alternative Methods of Hydrotherapy[edit | edit source]

There are many methods associated with hydrotherapy, some of the more commonly used ones are listed below[19]

The "WATSU® Method"[edit | edit source]

Also called “water Shiatsu", is a combination of Aquatherapy and Shiatsu. WATSU® is based on stretching the body in the supportive, relaxing medium of warm water. Beside the physical aspect, also the mental aspect has a great importance during this therapy. This method has a general relaxation and calming effect that soothes the muscle tension and stimulates all of the body systems and organs by nourishing the energy flow.[20]


The "Bad Ragaz Ring Method"[edit | edit source]

This is an aquatic treatment approach based on proprioceptive neuromuscular facilitation. With the use of floating rings at the neck, pelvis, knees, and/ or ankles, the Bad Ragaz Ring technique supports the patient in a vertical supine position. This method uses water that's 33 degrees Celsius and is a kind of resistive exercise that strengthens and mobilises. The patient shouldn't apply significant force and let the therapist work more force. Bad Ragaz Ring should be used in confluence with other strategies that aim to boost engagement and exertion. One such approach is the Halliwick approach.[22]


The "Feldenkrais Method"[edit | edit source]

This method promotes teaching individuals about the quality of their movements and how to move effortlessly with ease and efficiency.[24]


The "Halliwick Method"[edit | edit source]

This method takes a holistic approach using Aquatherapy as a learning activity for all people, particularly those with physical or learning difficulties, to be confident to move independently and become a part of a group setting involving water activities.[26]


The "Burdenko Method"[edit | edit source]

A method of Aquatherapy designed to address the 6 precepts of fitness: strength; flexibility; balance; co-ordination, endurance and speed. It is promoted as a great way to recover from injury or surgery.[28]


Resources[edit | edit source]

See the Australian Guidelines for Aquatic Physiotherapists Working in and/or Managing Hydrotherapy Pools for a description on what the Physiotherapist needs to consider with hydrotherapy.

References[edit | edit source]

  1. Bartels EM, Juhl CB, Christensen R, Hagen KB, Danneskiold‐Samsøe B, Dagfinrud H, Lund H. Aquatic exercise for the treatment of knee and hip osteoarthritis. Cochrane Database of Systematic Reviews. 2016(3). Level of evidence 1A
  2. Lori T. Brody, Paula R. Geigle (2009) Aquatic Exercise for Rehabilitation and Training. United states of America: Human Kinetics.
  3. 3.0 3.1 3.2 3.3 3.4 Kamioka H, Tsutani K, Okuizumi H, Mutoh Y, Ohta M, Handa S, Okada S, Kitayuguchi J, Kamada M, Shiozawa N, Honda T. Effectiveness of aquatic exercise and balneotherapy: a summary of systematic reviews based on randomized controlled trials of water immersion therapies. Journal of Epidemiology. 2010:20(1):2-12.
  4. 4.0 4.1 Khruakhorn S, Chiwarakranon S. Effects of hydrotherapy and land-based exercise on mobility and quality of life in patients with knee osteoarthritis: a randomized control trial. Journal of Physical Therapy Science. 2021;33(4):375-83.
  5. Amedoro A, Berardi A, Conte A, Pelosin E, Valente D, Maggi G, Tofani M, Galeoto G. The effect of aquatic physical therapy on patients with multiple sclerosis: a systematic review and meta-analysis. Multiple sclerosis and related disorders. 2020 Jun 1;41:102022.
  6. 6.0 6.1 Kim Y, Vakula MN, Waller B, Bressel E. A systematic review and meta-analysis comparing the effect of aquatic and land exercise on dynamic balance in older adults. BMC geriatrics. 2020 Dec;20(1):1-4.
  7. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Duffield M.H (1969) Exercise in water. Baltimore: The Williams & Wilkins Company.
  8. 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 8.11 Torres-Ronda L, i del Alcázar XS. The properties of water and their applications for training. Journal of human kinetics. 2014 Dec 30;44(1):237-48.
  9. 9.0 9.1 Joanne M. Koury. (1996) Aquatic therapy programming: Guidelines for orthopedic rehabilitation. United stats of America: Human Kinetics.
  10. Murry J. Advantages and concerns of aquatic exercise for cardiovascular rehabilitation patients [dissertation]. Wisconsin. University of Wisconsin. 2015.
  11. 11.0 11.1 Bukowski, E.L. (Sixth Edition). Aquatic Exercise. In C.Kisner, & L. A. Colby, Therapeutic Exercise - Foundations and Techniques (pp. 290-294). F.A Davis Co.
  12. Waller B, Ogonowska-Słodownik A, Vitor M, Rodionova K, Lambeck J, Heinonen A, Daly D. The effect of aquatic exercise on physical functioning in the older adult: a systematic review with meta-analysis. Age and ageing. 2016 Sep 1;45(5):593-601.
  13. Samhan A, Mohamed N, Elnaggar R, Mahmoud W. Assessment of the Clinical Effects of Aquatic-Based Exercises in the Treatment of Children With Juvenile Dermatomyositis: A 2x2 Controlled-Crossover Trial. Archives of Rheumatology. 2020 Mar 1;35(1):097-106.
  14. Lori T. Brody, Paula R. Geigle (2009) Aquatic Exercise for Rehabilitation and Training. United states of America: Human Kinetics.
  15. Bartels EM, Juhl CB, Christensen R, Hagen KB, Danneskiold-Samsøe B, Dagfinrud H, Lund H. Aquatic exercise for the treatment of knee and hip osteoarthritis. Cochrane Database Systematic Reviews. 2016:3(3):1-54.
  16. Heywood S, McClelland J, Mentiplay B, Geigle P, Rahmann A, Clark R. Effectiveness of Aquatic Exercise in Improving Lower Limb Strength in Musculoskeletal Conditions: A Systematic Review and Meta-Analysis. Archives of Physical Medicine and Rehabilitation. 2017:98(1):173-186.
  17. McNamara RJ, McKeough ZJ, McKenzie DK, Alison JA. Water-based exercise training for chronic obstructive pulmonary disease. Cochrane Database Systematic Reviews. 2013:12.
  18. Depiazzi J.E, Forbes R.A, Gibson N, Smith N.L, Wilson A.C, Boyd R.N, Hill K. The effect of aquatic high-intensity interval training on aerobic performance, strength and body composition in a non-athletic population: systematic review and meta-analysis. Clinical Rehabilitation. 2019:33(2):157-170.
  19. Mooventhan A, Nivethitha L. Scientific evidence-based effects of hydrotherapy on various systems of the body. North American journal of medical sciences. 2014:6(5):199-209.
  20. Schitter AM, Fleckenstein J, Frei P, Taeymans J, Kurpiers N, Radlinger L. Applications, indications, and effects of passive hydrotherapy WATSU (WaterShiatsu)—A systematic review and meta-analysis. PloSOne. 2020:15(3).
  21. International School of Watsu. A Watsu Basic sequence - part 1. Available from: (accessed 24/06/2008).
  22. Gamper UN, Lambeck J. The bad ragaz ring method. Chapter. 2011;4:109-36.In: Becker, BE and Cole, AJ and (eds). Comprehensive aquatic therapy, 3rd edition. Washington State University Press. 978-0615365671
  23. Johan Lambeck. Bad Ragaz Ring Method leg pattern. Available from : (accessed 20/12/2007)
  24. Neuroaquatics. Feldenkrais. Available from: (accessed 21/02/2019).
  25. Liga Latinoamericana de Fisioterapia Acuática. Feldenkrais. Available from: (accessed 25/07/2009)
  26. Vodakova E, Chatziioannou D, Jesina O, Kudlacek M. The Effect of Halliwick Method on Aquatic Skills of Children with Autism Spectrum Disorder. International journal of environmental research and public health. 2022:19(23):1-14.
  27. Johan Lambeck. Halliwick Critical factors clip 1. Available from: (accessed 11/08/2011)
  28. CanyonRanch. Burdenko water exercise. Available from: (accessed 21/2/2019)
  29. Cape Cod Rehab. Burdenko Pool Exercises. Available from: (accessed 25/09/2009)