Subarna Debbarma (BPT, DNHE)



Heat therapy,medically used by a Physiotherapist. Heat therapy also called thermotherapy, is the use of heat in treatment.

Mode of action Heat helps in the following ways:

• It reduces pain

• It relieves the stiffness of the joints

• It reduces the muscle tightness

• It increases the blood flow to the area by causing vasodilatation.

Benefits The heat therapy warms up the tissues and readies it for the future exercise therapy. Its action is similar to that of the warm-up exercises before the main exercises by sports persons.

Goal It aims to increase the temperature and increase the blood flow to the area of treatment.

Time Optimal benefits are achieved within 20 minutes of application. Beyond this time, there is no further increase or raise of temperature noted.

Types Two types are described:

1. Superficial heating agents these heat only the skin and

subcutaneous tissue (i.e. structures upto 10 mm beneath

the skin).

2. Deep heating agents these heat the deeper structures like

muscles and bones.


In this category are included the hydrocollator packs, infra-red lamps and paraffin baths. These are the most popular and common form of heat therapy advised after fractures.

Hydrocollator packs these packs contain silica gel which is encased in a canvas bag. This can be contoured to the various body regions.

Note Silica gel is able to maintain a heat of 40°C (104° of Fahrenheit) for a period of about 30-40 minutes.

Hydro collator pack is a form of conductive heat.


• Open wounds

• Anesthetic skin

• Significant edema

• Skin diseases and infections.

Infrared Infrared heating is delivered through an artificial source called the infrared lamp. This heats structures only 10mm beneath the skin.


• It induces relaxation in the patient.

• It mobilizes the skin and subcutaneous tissues.

• It provides no pressure on the body.

• The area under treatment can easily be inspected without

interrupting it.

• It is easy and simple to use even by the patient.

Optimum time Twenty minutes. It may cause burns, if allowed

to heat for long.

Contraindications These are the same as for hydro collator


Paraffin wax bath  this consists of a mixture of one part of liquid petroleum to seven parts of paraffin. It is most often indicated to treat small areas like hands and feet (as in Rheumatoid arthritis, etc.).

Contraindications are the same as for hydro collator packs.


Note Paraffin bath

• Immersion for short time heats only the skin and Subcutaneous tissue.

• Immersion for a longer time heats the deeper Structures like bones and joints.


Other superficial heating methods These include Hot packs,Hot water bottle and a small electric heating pad. They are Found to be equally effective as the other sophisticated methods Described so far. They have the advantage of being simple,Clean and easy to use even by the patients.

                          Fig: Hot pack

Caution Patient should be educated that too hot may be too

Bad and may cause burns.

Mode of action, indications, timing and contraindications are the same as for the other methods mentioned earlier.


These agents include microwave,shortwave,ultrasound etc and they act through the electromagnetic or mechanical waves.

They heat the structures 30-50 mm beneath the skin surface.



• Electromagnetic waves generate heat by tissue’s Resistance to electric current.

• Mechanical waves generate heat by causing tissue vibration.

Deep heating agents

Diathermy This term denotes deep heating by electromagnetic or mechanical waves.

• Heating by electromagnetic waves, e.g. Microwave or short wave.

• Heating by mechanical waves, e.g. ultrasound



• This is more frequently used method than the short wave.

• It is known to selectively heat muscles.

• It is indicated in muscle shortening following fractures.

• It is contraindicated if there is an implanted metal or if the patient has a cardiac pacemaker.


• These waves though called short, have a greater wave length than the microwaves.

• It heats the subcutaneous tissue more effectively than the superficial heat modalities.

• It is indicated in post fracture contractures and subcutaneous adhesions.

• Its usage now has declined in favor of microwave.

• The contraindications are the same as for microwave.


• Ultrasound waves are mechanical unlike shortwave and microwave.

• Ultrasonic waves are not faster than sound but have a greater frequency.

• It heats the bone muscle junction effectively.

• It is indicated in post-fracture muscle shortening and joint capsule contraction.

• Fractures fixed with implants are not suitable for ultrasound therapy.

Deep heat facts

• Microwave—selectively heats the muscle

• Shortwave—selectively heats the subcutaneous tissue

• Ultrasound—effectively heats the bone-muscle junction and the bones.

Other Deep Heat Therapy

 The general purpose of a deep heat therapy is to increase the extensibility of soft tissues, remove toxins from cells, enhance blood flow, increase the functioning of tissue cells, encourage muscle relaxation and help relieve pain.

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