Thermotherapy: Therapeutic effects depend on

  • method of heat delivery
  • mode of application (convection, conduction, radiation evaporation)
  • intensity and duration of stimulation
  • area and geometry of heat application
  • state of health and the individual reactivity of the patient

Therapies based on heat transfer:

Heat Convections: Packs and compresses are used to either maintain a constant body temperature or lower the body temperature.

Dry, warm or indifferent compresses are often used to maintain constant body temperature after another physical therapeutic method. The average temperature of a dry compress is 45ºC to 55ºC.
Cold and wet compresses are used to directly remove heat from the body surface(For instance, during fever). The average temperature of a wet compress is 60ºC to 70ºC.

Heat Conduction:  Whole Body Baths, Water Massages, and Saunas all have beneficial effects. Hydrotherapy is based on convection(movement of water) and mechanical effects(hydrostatic pressure).

Higher temperature assists in muscle relaxation, decreases pain sensations, and accelerates reabsorption of oedemas.

  • Whole body baths may be cold (<18ºC), cool (18ºC to 24ºC), tepid (24ºC-33ºC), warm (33ºC-36ºC), or hot (37ºC-42ºC).  The time of application depends on the bath type.
  • Water massage can be done using a stream of either cold or warm water, or a whirlpool bath of upper/lower limbs. In any case, both methods increase muscle tonus(passive strech during rest), local tissue metabolism, and activate skin receptors.
  • Sauna is the application of hot air (80ºC to 100ºC) with low humidity (10% to 30%). Followed by rapid cooling in cold water has pronounced activation effects.

Radiation: The radiant heat stimulates skin receptors, causing reflex vasodilatation, and muscle relaxation – a pronounced analgesic effect.

Radiant heat is used for heating the body at a depth of about 3mm. The sun is one natural source of radiant heat. Man-made sources of radiant heat include glowing wire coils and 250W incandescent lamps, emitting infrared light with wavelengths of about λ=0.8 to λ=40 μm.

Therapies based on heat production inside the body:

Reccomended reading:

High-Frequency Currents: At frequencies f>100 kHz AC has a heating effect.

By international agreements, the following frequency bands have been assigned for therapeutic purposes:

  1. short-wave diathermy: 27.12 MHz, λ=11.06 m
  2. ultrashort-wave diathermy: 433.92 MHz, λ=0.69 m
  3. microwave diathermy: 2450 MHz, λ=12.23 cm


  1. The targeted part is placed between two insulated electrodes. Dielectric losses of the newly formed capacitor will produce heat. The total amount of produced heat will depend on the electric properties of the body – maximum amont of heat is produced in muscles.
  2. Heat is produced by electromagnetic induction from a coil placed in the proximity of the surface of the body. Consequently Eddy Currents are also induced.
  3. Microwaves produced in a magnetron are emitted from an antenna, which is placed near the targeted region. The microwaves penetrate deep into the tissues causing movement of electrically charged particles  in the High Frequency electric field.

All the methods of high frequency electric current application are used in the treatment of injuries of the locomotor apparatus.

I suppose that the effects of those treatements are:

  • Higher rate of transpiration
  • Increased metabolism
  • Dilation of veins and arteries, therefore
  • Faster healing and
  • Reduction of pain.

Ultrasound: Is directed towards a tissue to be treated. 30% to 40% of applied acoustic energy is transformed into heat during absorption. Maximum heat production is relative to the different acoustic impendances of tissues.