HYDROTHERAPY: Definition of Terms, Effects, Principles, CIs, Examples of Hydrotherapies

What is Hydrotherapy?

Hydrotherapy, or water therapy, uses water in any of its forms to improve health and well-being by taking advantage of its temperature, pressure, and buoyancy properties. This practice dates back to ancient times and is still used today in home self care settings, spas and physical therapy and massage clinics.

Hydrotherapy treatments can range from simple practices such as warm baths or application of heat packs, to specialized treatments requiring facilities such as physical therapy tanks, swimming pools, whirlpool spas, hot tubs, and saunas.

Hydrotherapy Terms Definition

  • Active Hyperemia – caused by increased blood flow demand, such as from heat therapy, enhancing circulation and promoting healing.
  • Chemical Warmth Regulation– combination of efects from retrostasis and derivation. The cold stimulus triggers the heat production center of the brain, resulting in an increase in metabolism and hormone secretion. This is the ody’s way of staying warm with a cool application.
  • Cryotherapy – sometimes known as cold therapy, is the local or general use of low temperatures in medical therapy.
  • Derivation – action of drawing blood from one area to the surface of a distal area in order to relieve congestion elsewwhere.
  • Diaphoretic – an agent that produces perspiration.
  • Hunting’s Response – also known as the Lewis reaction, is the body’s alternating reaction to prolonged cold exposure. Initially, blood vessels constrict to preserve heat (vasoconstriction). After about 5 to 10 minutes, the blood vessels periodically dilate (vasodilation) to increase blood flow and prevent tissue damage. This cycle of constriction and dilation can continue to protect the skin and extremities from cold injury. Iintermittent vasodilation lasting 4-6 minutes. This is a protective mechanism to prevent tissue damage from ischemia.
  • Hydrocollators – gel-filled heat packs.
  • Hyperemia – refers to an increased blood flow to a specific area of the body, resulting in redness, warmth, and sometimes swelling.
  • Passive Hyperemia – occurs when cold application is used to create a temporary restriction in blood flow, followed by a period of
  • unrestricted flow. This “rebound effect” leads to a surge in blood flow to the treated area, causing localized redness (hyperemia).
  • Physical Warmth Regulation – thermoregulators in the skin and the internal rise in temperature stimulate the hypothalamus to trigger the heat loss center (body’s response to remove excess heat from the body.)
  • Retrostasis – diversion of blood from the surface vessels of the skin to the interior of the body.
  • Thermophore – moist electric heating pad.
  • Van Hoff’s Law – with every 10°C rise in temperature, there is an increase in chemical reaction of the blood by 2-3 times.
  • Vasoconstriction – the narrowing (constriction) of blood vessels by small muscles in their walls. When blood vessels constrict, blood flow is slowed or blocked.
  • Vasodilation – the widening of blood vessels as a result of the relaxation of the blood vessel’s muscular walls. Vasodilation is a mechanism to enhance blood flow to areas of the body that are lacking oxygen and/or nutrients.
  • Vasostasis – the stopping or slowing of blood flow within blood vessels.


Principles of Hydrotherapy

1. Temperature and Blood Flow:

  • Warm water (38-42°C or 100-108°F): Promotes vasodilation leading to active hyperemia. This increased blood flow delivers nutrients and oxygen to the targeted area, aiding healing, reducing muscle tension, and improving joint mobility.
  • Cold water (less than 18°C or 64°F): Causes vasoconstriction followed by vasodilation upon removal, creating passive hyperemia. This surge in blood flow helps remove inflammatory byproducts and promotes healing, making it beneficial for managing inflammation and pain.
  • Cryotherapy reduces inflammation, numbs pain, and decreases blood flow.

2. Pressure and Buoyancy:

  • Water pressure: Applied through jets or movement in a pool can improve circulation throughout the body, reduce edema (swelling), and provide gentle resistance for therapeutic exercise.
  • Buoyancy: Buoyancy reduces the weight-bearing load on joints and muscles when submerged in water, making movements easier and less painful. The ability of water to support body weight reduces stress on joints and allows for pain-free movement, facilitating earlier mobilization and exercise in physical therapy programs.

3. Hydrostatic Pressure:

  • Hydrostatic pressure exerted by water on the body helps to reduce swelling and edema by assisting venous and lymphatic return. In physical therapy, hydrostatic pressure of water is used to facilitate exercises and movements that may be difficult or painful on land, especially for individuals with arthritis, musculoskeletal injuries, or mobility impairments.

4. Water Resistance:

  • Water provides resistance to movement, which helps to strengthen muscles, improve cardiovascular fitness, and enhance proprioception. Examples are aquatic exercises, such as water aerobics, swimming, and resistance training, are used to improve strength, endurance, and balance, particularly for individuals with joint pain or weakness.

General Principles of Hydrotherapy:

  • Thermal effects occur with applications of water at temperatures above or below the temperature of the body.
  • The greater the temperature difference, the more pronounced the effects
  • Hydrotherapy may be used over the entire body or locally.
  • Generally, clients should rest following any full-body hydrotherapy treatment, for at least the same length of time as the hydrotherapy was applied.
  • The weight of an individual hydrotherapy application is considered before use.
  • The effects of the application vary depending on the temperature and the length of time it is applied
    for example:

    • a brief application of cold ( <1 min) provokes the body to maintain thermal and circulatory equilibrium. Local vasoconstriction in the skin from the quick cold application is followed by vasodilation.
    • A short application of heat ( < 5 minutes) stimulates circulation with local cutaneous vasodilation followed by vasostasis.

Uses of Hydrotherapy

  • Heat and cold therapies are used to manage pain, stiffness, and inflammation in acute and chronic musculoskeletal conditions, such as sprains, strains, and arthritis.
  • Hydrotherapy techniques promotes healing, reduces pain and inflammation, and facilitates early mobilization, all crucial for post-surgical recovery.
  • The buoyancy and support of water can be particularly beneficial for individuals with neurological conditions, allowing for safe and supported movement to improve balance and coordination.
  • Aquatic exercises utilize the resistance and support of water to improve strength, flexibility, and range of motion in a low-impact environment.
  • Hot compresses or contrast therapy on specific areas can address superficial muscle tension.
  • Soaking in a warm bath can help promote relaxation and reduce muscle soreness.
  • Applying warm water (using heat packs or hydrocollators) before a massage warms up the muscles – making them more pliable and receptive to massage techniques, improving the overall effectiveness of the massage.


Effects of Hot and Cold Hydrotherapy

Effects of Heat

  • Locally, there is an increase in tissue temperature.  Application of heat to the limbs causes a marked increase in blood flow distal to the heat source. There is a also a reflex increase in blood flow in the contralateral limbs.
  • Heat between 42 and 45 °C increase the extensibility of collagen tissue, making joints and muscles more flexible.
  • Promotes the activity of enzymes involved in tissue repair and regeneration, accelerating the healing process.
  • Improves circulation and metabolic activity which facilitates the delivery of nutrients and oxygen to injured tissues, aiding in their recovery.
  • Relaxes muscle fibers and reduce muscle tension by increasing the elasticity of soft tissues. Relaxed muscles can alleviate stiffness, improve flexibility, and reduce pain associated with muscle spasms or tightness.
  • Heat application causes blood vessels to dilate, increasing blood flow to the affected area. Enhanced blood circulation delivers more oxygen, nutrients, and immune cells to tissues, promoting healing and tissue repair.
  • Help alleviate pain by blocking pain signals to the brain and triggering the release of endorphins, the body’s natural painkillers. Heat also reduces the sensitivity of pain receptors and decreases muscle spasm, providing relief from both acute and chronic pain conditions.
  • Stimulates metabolic activity in cells, enhancing tissue metabolism and facilitating the removal of metabolic waste products.
    Improved metabolism can accelerate healing, reduce inflammation, and promote overall tissue health.
  • Induces a feeling of relaxation and comfort, promoting a state of relaxation in both body and mind. Heat therapy can help reduce stress, anxiety, and tension by calming the nervous system and promoting a sense of well-being.

Effects of Cold

  • Cold application causes blood vessels to constrict (vasoconstriction), reducing blood flow to the affected area. Decreased blood flow helps to reduce inflammation, swelling, and pain associated with acute injuries or inflammatory conditions.
  • Causes analgesic (pain-relieving) effect. Cold therapy numbs nerve endings, decreasing the transmission of pain signals to the brain. Cold application can provide immediate pain relief for acute injuries, post-surgical pain, or inflammatory conditions like arthritis.
  • Helps to decrease the production of inflammatory mediators and the permeability of blood vessels, reducing the accumulation of fluid in tissues. Cold therapy is effective in managing swelling, edema, and inflammation following acute injuries or surgical procedures.
  • Application of cold therapy numbs the area, providing a temporary local anesthesia effect. Cold packs or ice massage can be used to numb the skin before minor medical procedures or to reduce pain during physical therapy sessions.
  • Can help relax muscles by reducing muscle spasms and decreasing muscle activity. A brief cold application is beneficial for relieving muscle tension, stiffness, and soreness following intense physical activity or overuse.
  • Cold therapy can help preserve tissue viability and minimize cellular damage in cases of acute injury or trauma by decreasing metabolic activity in cells, slowing down enzymatic reactions.e
  • Slows down nerve conduction velocity, reducing nerve sensitivity and decreasing muscle spasticity. Cold therapy can be used to manage conditions like nerve pain (neuralgia), muscle cramps, and spasticity in neurological disorders.

Contraindications for Hydrotherapy

While heat and cold hydrotherapy can be beneficial for many conditions, there are certain situations where they may not be appropriate or may require caution. Here are some contraindications for heat and cold hydrotherapy:

7 Contraindications for Heat Hydrotherapy:

  1. Avoid heat therapy in the acute phase of injuries, such as sprains, strains, or fractures, as it can increase inflammation and swelling.
  2. Heat should not be applied to open wounds or areas of broken skin, as it can increase the risk of infection and delay wound healing.
  3. Heat therapy should be avoided in individuals with impaired sensation, such as neuropathy or paralysis, as they may not be able to detect or tolerate excessive heat, leading to burns or tissue damage.
  4. Heat therapy may worsen symptoms in individuals with peripheral vascular disease (PVD) or compromised circulation, as it can further dilate blood vessels and increase the risk of tissue damage.
  5. Heat therapy should not be used over areas of active infection, as it can promote bacterial growth and exacerbate the infection.
  6. Avoid heat therapy over areas of acute or chronic skin conditions, such as dermatitis, eczema, or psoriasis, as it can aggravate symptoms and worsen the condition.
  7. Heat therapy should be used with caution during pregnancy, particularly over the abdomen or lower back, as excessive heat can raise core body temperature and potentially harm the developing fetus.

7 Contraindications for Cold Hydrotherapy:

  1. Cold therapy should be avoided in individuals at risk of hypothermia, such as those with poor circulation, elderly individuals, or young children, as prolonged exposure to cold temperatures can lower core body temperature.
  2. Symptoms in individuals with Raynaud’s phenomenon, a condition characterized by exaggerated vasospasm in response to cold exposure, may be exacerbated, leading to pain and discoloration of the fingers and toes.
  3. People with cold urticaria, a condition characterized by hives or skin rash in response to cold exposure, should avoid cold therapy as it can trigger an allergic reaction.
  4. For those with cold sensitivity or intolerance, cold therapy may cause discomfort or pain.
  5. Individuals with cryoglobulinemia, a condition characterized by abnormal proteins in the blood that precipitate in response to cold exposure, should avoid cold therapy as it can lead to blood vessel inflammation and damage.
  6. Those with compromised circulation, such as peripheral vascular disease (PVD) or diabetes, should use cold therapy with caution, as it can further impair blood flow and increase the risk of tissue damage.
  7. Cold therapy should be avoided over areas of nerve injury or neuropathy, as it can exacerbate nerve sensitivity and symptoms such as tingling, numbness, or pain.


Examples of Hydrotherapy Modalities

Hydrotherapy modalities encompass a variety of therapeutic treatments that utilize water to promote healing, relaxation, and overall well-being. These modalities are incorporated into treatment plans based on individual needs and goals.  Here are some common hydrotherapy modalities:

Aquatic Exercise

Performing exercises in a pool or aquatic environment to improve strength, flexibility, and cardiovascular fitness while reducing the impact on joints. Aquatic exercise is beneficial for individuals with arthritis, joint pain, or mobility issues.

Cold Packs/ Cold Compress

Applying cold packs or ice directly to the skin to reduce inflammation, numb pain, and promote vasoconstriction. Cold therapy is commonly used in the treatment of acute injuries, such as sprains and strains.

Contrast Baths

Alternating between hot and cold water baths or showers to stimulate circulation, reduce inflammation, and promote tissue healing. This modality is often used in sports therapy and rehabilitation. The warm water promotes vasodilation (blood vessel widening), followed by vasoconstriction (narrowing) with cold water. This cycle creates a surge in blood flow upon returning to warm water (passive hyperemia), which can further reduce inflammation and muscle tension.

Heat Packs/ Warm Compresses

Applying heat to the body using warm compresses, heating pads, or heat packs to relax muscles, increase circulation, and relieve pain. Heat therapy is often used for chronic conditions, such as arthritis and muscle tension.

Hydro-Massage Tables

Tables equipped with water-filled cushions or jets that provide massage therapy while the client lies comfortably on the surface. Hydro-massage tables are used to relax muscles, relieve tension, and promote relaxation.

Hydrotherapy Showers

Showers equipped with multiple showerheads that deliver various water pressures and temperatures for therapeutic effects. Hydrotherapy showers are used to invigorate the body, promote circulation, and relieve muscle tension.

Ice Massage

Water is frozen in a paper cup; the edge of the cup is peeled back, giving the therapist an easie way to handle the ice than if it were just an ice cube. The ice is rubbed over the skin surface in a circular manner. The duration of the application is around 10 minutes.

Steam Rooms

Steam rooms are enclosed spaces that generate high humidity and heat, typically around 43°C to 49°C (110°F to 120°F), through steam production. They offer various health benefits, including improved respiratory function by relieving congestion and sinus pressure, enhanced skin hydration and detoxification, and muscle relaxation, aiding in pain relief and recovery. The heat also promotes vasodilation, improving circulation and cardiovascular health, while the warm, soothing environment helps reduce stress and anxiety.

Sitz Baths

A shallow bath in which only the hips and buttocks are immersed in water. Sitz baths are commonly used to relieve discomfort and promote healing in the pelvic area, such as after childbirth or for hemorrhoid relief.

Vichy Shower

A Vichy shower is a hydrotherapy treatment that involves multiple shower heads and multi-directional spraying water over the body while the client lies on a treatment table. Named after the spa town of Vichy in France, this therapy is commonly used in spas and wellness centers to provide relaxation and therapeutic benefits.

Warm Soaks/ Baths

Immersing yourself in warm water (around 38-42°C or 100-108°F) promotes relaxation, reduces muscle tension, and improves blood flow (active hyperemia). This can be done at home or in a spa setting.


This form of massage therapy involves passive stretches and manipulations while the client is comfortably supported by the buoyancy of warm water.

Whirlpool Baths

Immersing the body in a bathtub equipped with water jets that provide massage and hydrotherapy. Whirlpool baths are used to relax muscles, reduce pain, and promote circulation.


Other Thermal Applications in Hydrotherapy

Hydrotherapy, or water therapy, originally referred to using water in various forms (like hot or cold baths) for therapeutic purposes. Over time, the term hydrotherapy has expanded to include thermal applications which are not pure water, such as wax baths, thermophores, hydrocollators, and freezable gel packs. The term has expanded to include other thermal treatments that aren’t strictly water-based but still use temperature for healing. Here are some examples:

Wax Baths (Paraffin Baths)

Involves immersing a body part (like hands or feet) into warm, melted paraffin wax. The heat from the wax penetrates deep into the skin and muscles. It helps relieve pain, sooth stiff joints, and moisturize the skin. Paraffin wax baths are used for conditions like arthritis and muscle stiffness.

Thermophores (Moist Electric Heating Pads)

These are electric pads that provide moist heat to specific body areas. Moist heat penetrates deeper into the muscles compared to dry heat.
It reduces muscle pain and spasms, improves blood flow, and helps in relaxation.

Hydrocollators (Gel-Filled Heat Packs)

Hydrocollators are packs filled with a gel that retains heat for a prolonged period. They provide consistent, penetrating heat to relieve muscle pain and stiffness. Commonly used in physical therapy.

Freezable Gel Packs

These packs can be frozen and applied to injuries. Ideal for treating acute injuries, reducing inflammation, and soothing sore muscles. The cold from the gel pack reduces swelling and numbs pain.