Interferential therapy is a form of treatment that involves the use of 2 medium frequency current to bring out the effect of a low frequency current in the tissues. Skin impedance. Principal of IFT. Beat frequency.

1. Interferential therapy
Name :- Shruti
Kumari

2. Introduction
■ It is a type of electrotherapy treatment that uses electric currents to stimulate tissue which
provides pain relief, reduction of swelling and many other health benefits.
■ The principle of interferential therapy is to cause two medium frequency currents of
slightly different frequencies to interfere with one another.
■ It is basically used for the treatment of Chronic, Post Traumatic, and Post-surgical pains.
■ IFT uses a range of frequencies that stimulate the body to get positive reactions such as
increasing the blood supply in an area which in turn increases the healing speed.
■ The major advantage of IFT is that it produces effects in the tissue, exactly where required
without unnecessary and uncomfortable skin stimulation.
■ This technique is widely used to elicit muscle contraction, promote healing and reduce
edema.
■ IFT is the form of the electrical treatment in which two medium frequency currents are
used to produce a low – frequency effect .

3. Skin impedance Interferential therapy
■ Main problem of direct application of faradic or sinusoidal currents to patient is the very high skin impedance.
■ Medium frequency current of around 4000Hz , while able to stimulate motor and sensory nerves, encounter a
much Lower skin impedance .
■ Impedance is inversely proportional to frequency.
Formula of skin impedance :
■ Z= 1/2 pfC
■ where , Z = impedance in ohms
■ f =frequency in hertz
■ C= capacitance of skin in micro farads

4. Principles
■ It is to pass two medium frequency alternating currents which are the slightly
out of phase, through the tissue., where the currents intersect to produce a
low frequency effect.
Duration of treatment :
■ Between 10 – 20 minutes.
■ Mostly used 10 minutes

5. Electrodes placement for Interferential therapy :
El
■ or Interferential therapy use to for electrodes [ 2 pair electrodes ]
■ Each pair indicated by the coloring wire form the machine.
■ 2 electrodes = black and 2 electrodes = red .
■ So in pair = 1 electrode black and 1 electrode red.
■ The electrodes of each pair are placed diagonally opposite one another.
■ So that beat frequency is produced in the tissue where it required.
Testing of the Interferential therapy machine :
■ First of all on the plinth placed 4 electrode in positing of electrode.
■ After that put the hand on center of the electrodes.
■ Then increase to intensity and feel to current.

6. Technique of treatment of Interferential therapy
■ Patient position = comfortable .
■ Skin = washed and apply petroleum jelly on the lesions .
■ After that place the electrode on the site of treatment .
■ Instruct to patient if feel a tingling sensation please tell to therapist .
■ On that time decrease the intensity .
■ Beat frequency of Interferential therapy
■ When to apply Interferential therapy two frequency current is used.
■ If one of the currents is kept in constant of 4000 Hz and other can be varied between 3900 and
4000 Hz
■ And interference effect at the called beat frequency.
■ Beat frequency is equal to difference in frequency between the two currents.
■ It is produce in the tissue at the point where the two current cross.

7. Dosage of Interferential therapy :
:
■ For pain relief = 80 – 100 Hz
■ For reduce swelling = 1 – 10 Hz
■ Reduce edema = 100 Hz
■ For partial tetany contraction = 5 – 20 Hz
■ For tetany contraction = 30 – 100 Hz
■ Apply for 15 minutes

8. Physiological effect of
Interferential therapy
Indication Contraindication
■ Pain relief
■ Motor stimulation
■ Absorption of exudate
■ Increase the local
blood flow
■ Reduction of edema
■ Rheumatoid arthritis.
■ Frozen shoulder.
■ Disc herniation.
■ Spinal canal stenosis.
■ Reduction of Edema
■ Muscle injuries
■ Ligaments injuries
■ Stress incontinence
■ Cervical spondylosis.
■ Osteoarthritis of the knee.
■ Infective condition
■ Malignancy
■ Pacemakers
■ Loss of sensation.
■ Large open wounds
■ Dermatological Conditions
■ Pregnant Uterus
■ Hypertension
■ Thrombosis
■ Hemorrhage
■ Neoplasm
■ Tb
■ Fever

9. Thank you