Terminology in aquatic physical therapy

This is the network of aquatic physical therapy. We chose this name in order to be in line with the World Confederation for Physical Therapy. Aquatic physical therapy or aquatic physiotherapy is also still known as hydrotherapy.

The Aquatic Therapy Association of Chartered Physiotherapists (ATACP, United Kingdom) wrote in 2008: "prior to 2008 aquatic physiotherapy was called ‘hydrotherapy’ in the UK. The reason for the change to aquatic physiotherapy was two-fold:

  1. to be in line with the international term aquatic physical therapy, and
  2. to make use of the protected term physiotherapy."

The ATACP defines aquatic physical therapy as: "A therapy programme utilising the properties of water, designed by a suitably qualified physiotherapist specifically for an individual to improve function, carried out by appropriately trained personnel, ideally in a purpose built, and suitably heated hydrotherapy pool" (ATACP, 2008). Also the South African Aquatic Physiotherapy Group (2009) uses a definition which is very much alike: “Aquatic physiotherapy is physiotherapy which uses more than one of the unique properties of water for therapeutic rehabilitation”.

A Dutch definition, used in courses of the Dutch Centre of Allied Health Care (NPI) is: "Aquatic (Physical) Therapy is a programme, using mechanical and thermal characteristics of water during partial or complete immersion, in combination with the effects of movement. It evokes short-term and long-term adaptational mechanisms of a person with a deranged biological system, using specific stimuli to create biological and thus therapeutic effects."

Jenny Geytenbeek, author of the Aquatic Physiotherapy Evidence-Based Practice Guide (2008), published by the National Aquatic Physiotherapy Group of the Australian Physiotherapy Association, gives the following definition and explanation:

""Aquatic Physiotherapy” refers to the special practice of physiotherapy, with therapeutic intent toward the rehabilitation or attainment of specific physical and functional goals of individuals using the medium of water. It differs from the more generic term “hydrotherapy” which connotes any water-based therapy conducted by an array of professional specialties, including immersion in warm water, immersion in mineralized water (balneotherapy and spa therapy), immersion in mechanically turbulent warm water (spa therapy), application of pressurized water to the external body (whirlpool), application of warm water into the colon (colonic irrigation), the application of water of various temperatures and pressures via showers and towels (Kneipp therapy), and movement-based therapy in water (hydrokinesiotherapy). “Aquatic therapy” similarly refers to water-based activity of therapeutic intent, is common among American literature, and includes the practice of eg physical therapists, exercise therapists, nurses and exercise instructors. “Aquatic exercise” has the intention of fitness training in both healthy and symptomatic individuals, and “water exercise” is its synonym."

Aquatic physical therapy can be applied at all three dimensions of the International Classification of Functioning, Disability and Health (World Health Organisation, 2001). A fourth dimension is Quality of Life, also an important goal in Aquatic Physical Therapy.

Aquatic physical therapy might also be supportive in treating some of the modern life-style conditions as well. A special issue of Physiotherapy Theory and Practice titled ‘Physiotherapy practice in the 21st century: a new evidence-informed paradigm and implications’, identified topics like nutrition and weight control, sustainability of physical activity and exercise, management of sleep disturbance and undue life stress. Evidence is still scarce, but issues like obesitas (Nagle 2007), adherence (Kang 2007), management of sleeping patterns (Vitorino 2006)  and stress reduction (Bood 2009) have been addressed in aquatic literature, see also the chapter of the physiology of immersion and the autonomic nervous system.

Aquatic physical therapy exercise

Aquatic physical therapy has a large focus on exercise in water which can include the following used in isolation or in combination:

  • Balance training
  • Strengthening and stabilising
  • Cardiovascular conditioning
  • Adapted swimming
  • Flexibility or exercises for range of movement

Aquatic exercise is prescribed specifically for the participant following an assessment to identify main problems and includes the integration of evidence based practice along with shared goal setting.  Specificity with exercise prescription remains a high priority along with further considering dose response to aquatic physical therapy. Focus must continue on outcome measures for measuring effectiveness and objective measures to improve accuracy of estimating load. Examples are a metronome or music for speed and resistance from turbulence, volume of floatation for buoyancy resisted exercise, repetitions and sets and measures of cardiovascular load. The use of outcome measures and objective measures will facilitate the transition from practice to research and vice versa.  Nearly all aquatic approaches and exercises offer direct benefits to stabilising or strengthening.  Resistance training in aquatic physiotherapy can have excellent outcomes. Clear protocols with progressive load, understanding the physics of the environment and measuring forces is important.

The aquatic environment is ideal for cardiovascular training not only for sporting populations or basic musculoskeletal rehabilitation but also in chronic conditions with support documented in patients with Rheumatoid Arthritis (Hall et al 2004), chronic low back pain (Barker et al 2003) and stroke (Driver et al 2004). The nature of any chronic condition is often reduced mobility and subsequently reduced VO2 max. With continuing research into this area, consideration should be given in all chronic patients to planning part of each session to address improving their VO2 max.  The aquatic environment can be an exercise medium safe from falls or injury, it can also be highly challenging more at the edge of balance limits including practice in single limb stance. Larger movements of the centre of gravity, limbs and trunk are therapeutically useful but it is unclear if any influence on the fear of falling. Balance is specific to the environment and the task but aquatic programs have shown carryover into land based measures.

Adapted swimming covers all strokes that may be in some way modified. Adapted swimming offers not only a cardiovascular training, musculoskeletal challenge in terms of endurance and range of movement but most importantly it offers so much with regard to participation.

The physiology of immersion and the autonomic nervous system

The physiological changes upon immersion in thermoneutral water are well documented including the blood volume shift from the periphery to the central circulation due to hydrostatic pressure (Hall 1990, Becker 2009). The impact of increased stroke volume and cardiac output and reduced heart rate in addition to lung volume changes appears clinically well tolerated and beneficial but needs further investigation in chronic populations for general fitness or rehabilitation following a cardiac event or with pulmonary rehabilitation. The autonomic nervous system is made up of two opposing branches, the sympathetic (ergotropic/fight or flight) component and the parasympathetic (trophotropic/relaxation and recharging) component. Many chronic disease states have autonomic system changes or an imbalance between the two components. Increased sympathetic nervous system activity has been associated with cardiac dysfunction and autonomic imbalance is likely to also have a significant impact during and after prolonged periods of stress and influence mental health. The mechanisms of autonomic nervous system function are complex and the exact influences leading to reduced sympathetic nervous system activity when immersed are unknown. This area of research may help to further understand some physical and mental or emotional health interrelationships with immersion leading to a similar response to relaxation or meditation.

Aquatic physical therapy techniques

Aquatic physical therapy is primarily focused on exercise in water but also includes hands-on techniques. It can include some of the methods mentioned underneath, it can also include joint mobilizing or stretching techniques or other passive relaxation techniques, it can also include gait or postural re-education.  All techniques can be combined depending on the individual’s goals.

In order to achieve specific physical or functional  goals, aquatic physical therapists can choose a number of concepts (methods or techniques). Well-known concepts from Europe are The Halliwick Concept (1949) or the Bad Ragaz Ring Method (1955). The USA  has given us Deep Water Running or Aquajogging (1970) and Watsu (early 1980s). More recently, Ai Chi has been developed in Japan (1993).

The reason for the choice to give a short descriptionof these concepts is the availability of courses, information on the internet and the choice of editors of recent American textbooks on aquatic therapy to include these concepts in their books.


Halliwick is a concept, originally developed to teach clients with a (physical) disability to swim and to make them independent in water. Independence is an important prerequisite for participation in therapeutic, vocational or recreational activities in a group: the willingness to loose balance and knowing how to stand up again are core elements.

A Ten-Point-Programme is used to reach these goals. The most important part of this programme is rotational control, also basis for a second part of the Halliwick Concept: Water Specific Therapy (WST). This part is focused on eg postural control, normalising muscle stiffness and facilitation of movement.

Halliwick is a problem solving approach. Possibilities and constraints of the client are analysed in order to use a systematic intervention (Ten-Point-Programme and/or WST) to help the client gain functional increases.

Mostly Halliwick is dynamic to facilitate movement and sensory input. Halliwick also has a static part, in which e.g. selective activation of muscles and stabilisation of specific joints is exercised.

Halliwick can be used to address objectives at all levels of the International Classification of Functioning, Disability and Health (ICF).

The Halliwick Concept has vast possibilities. In neurological and paediatric rehabilitation, clients can experience early mobility. The mechanical advantages of water support the abilities of the trunk in a mobilising and stabilising way. In this sense Halliwickis a constraint-induced movement therapy without the disadvantage of gravity compensation.

Many activities easily can be repeated and varied and clients can learn balance- and stumble- strategies, which have carry-over effects to dry land.

Halliwick enables also a graded activity programme: with low mechanical impact and increasing physiological demand, chronic low back pain patients and others can increase their functional capacity in a mostly joyful way.

The amount of moderate to even high quality clinical trials has increased enormously in the past decade, giving Halliwick a stable evidence base.

The Bad Ragaz Ring Method

The Bad Ragaz Ring Method (BRRM) is an active technique in which the therapist provides manual resistance to a client, supported by flotation aids. The patient is facilitated, mainly proprioceptively to activate weak muscles. BRRM follows the principles of Proprioceptive Neuromuscular Facilitation (PNF), but is adapted to the possibilities and difficulties of moving in an aquatic environment. BRRM exists of some 23 patterns of arms, trunk and legs. In various patterns, PNF techniques like e.g. combination of isotonics or reversalof antagonists can be used. Apart from that, muscle strengthening physiology has been included the last decade. The main objectives of BRRM are activating weak muscles through the principles of segmental irradiation, increasing muscle power and muscular stabilization of joints. The BRRM therefore is limited to the function level of ICF and has no direct task- or goal oriented objectives.

The evidence is limited, showing only about 4 research articles. Expert opinion still is the base of this method.

Deep Water Running (DWR)

DWR is a technique in which clients, mostly supported by a specific device – wetbelt or aquajogger – walk or run through deep water. The rationale is to use a frontal plane as large as possible in order to achieve maximal impedance. This is the basis of cardiovascular/pulmonal training, in general focused on aerobic conditioning. DWR is not a “typical” aquatic physical therapy application, but many clients treated in physical therapy have a limited stamina/aerobic condition. The aquatic physical therapist should be able to match the reduced carriability of these clients with the proper application of the external load using DWR.

DWR (and many other aquatic physical fitness techniques) are examplesof techniques that both can be used in aquatic physical therapy as well as in aquatic exercise.

The evidence of the value aerobic conditioning in water is huge. The method is not that important, as long as the (ACSM) rules for cardiovascular conditioning are obeyed.


Watsu originates from Zen-Shiatsu in water and started as a wellness technique. The client (or receiver) is completely passive and is moved gently by the practitioner (or giver) through the water. The goal is to stretch meridians and to balance energy flow in the body. This means that the client tends to relax (deeply). Various reasons might explain this deep relaxation, an important one is probably the effect on the autonomous system through cutaneous and kinaesthetic afferent information.

By applying passive motion to a client, the visco-elastic stiffness of connective tissue in arthrogenic, musculotendinogenic and neurogenic tissues can be addressed.

Watsu is highly valued by clients and practitioners claim a large amount of health benefits. The evidence base is small however with only a few clinical trials. Because of the high value, quite an amount of variations exist worldwide.

Ai Chi

Ai Chi is often described as a simple aquatic form of T’aiChi in combination with Qi Gong. There are resemblances, but the basis is Zen-Shaitsu. It is an active technique in which balance, breathing and relaxation come together.

The evidence base still is small, but clinical trials have shown large effect sizes on balance scales (Berg Balance Scale and POMA). Because of this, it is hypothesised that it can be used well in falls prevention, especially in populations that have difficulty to enter in land falls prevention programmes. The repetitive slow movements are thought to positively affect visco-elasticity of connective tissue while at the same time increase coordination.