This PowerPoint presentation provides a comprehensive, evidence-based overview of Interferential Therapy (IFT) as part of Electrotherapy for BPT 2nd-year physiotherapy students. Key topics covered include: Principles of Interferential Therapy Production of Interference Current Types of IFT (2-pole and 4-pole) Physiological effects and therapeutic benefits Clinical indications and contraindications Electrode placement techniques Dosage parameters and treatment protocols Recent advances and research evidence This presentation is ideal for physiotherapy students and educators looking to understand the fundamentals and clinical applications of IFT in rehabilitation practice.

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Interferential Therapy (IFT)
P r e p a r e d b y
D r . S O M A B A L A J I P T
M S K & S P O R T S

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Learning Objectives
•U n d er s ta n d the pri nc iple a nd mec h an is m of IF T
•L ea r n th e t e ch nic a l a sp e ct s a nd s et t in gs
•Kn ow th e ph ys io log ic al ef f e ct s
•M as te r the c lin ica l ap pli ca t i ons a nd
c ont r ai nd ica t i ons
•R e v ie w ev id e nce - b as e d e f f ec t iv e ne ss
•O b s er v e pra c t ic a l d emon st r at i on an d el ec t rod e
pl ac e me nt s

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Introduction
•IFT i s a med iu m- f re q ue nc y el e ct r o the r a p y
mo d a lit y
•Pr i ma r i ly u s ed f or pa in re lie f , musc le
st imu la t io n , a n d in cre a sin g circ u lat ion
•Wor k s o n th e pr i n ci p le of int erf ere nc e of
t w o cu rren t s to p r o du c e lo w - f re que n cy
t he rap e ut i c ef f ec t

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Historical Background
•Introduced by Dr. Hans Nemec (Austria, 1950s)
•Popularized in physiotherapy by European researchers
•Evolved with digital interferential units and portable
devices

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Definition
"IFT is the use of two medium-frequency alternating currents which intersect and interfere
within the tissues to produce a therapeutic low-frequency current."

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Basic Principle
•Two medium-frequency currents: 4000 Hz and 4100 Hz
•These cross and interfere in the body tissues
•Results in a beat frequency = 100 Hz
•This beat frequency provides low-frequency stimulation at deeper tissue levels

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Types of Interference
1. Constructive Interference – Enhanced current amplitude
2. Destructive Interference – Reduced amplitude
3. Continuous Interference Pattern – Varies based on frequency and vector

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Types of IFT Application
1. Bipolar – Pre-modulated current (two electrodes)
2. Quadripolar – Classic interference (four electrodes)
3. Vector Scan – Rotating field for larger area coverage
4. Stereodynamic IFT – 3D modulation in advanced units

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Electrode Placement
•Cross pattern (Quadripolar): Diagonal positioning for interference
•Bipolar: Current modulated within the machine
•Targeted placement: Over trigger points, muscle belly, joints

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Parameters of IFT
•Carrier frequency: 4000 Hz (base)
•Beat frequency: 1–150 Hz
•Sweep frequency: Varies the beat (to avoid accommodation)
•Treatment time: 10–20 minutes
•Amplitude: Based on patient tolerance (usually strong but comfortable)

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Frequency Effects (Clinical Relevance)
•0–10 Hz: Muscle stimulation
•10–20 Hz: Increases circulation
•20–50 Hz: Muscle relaxation
•90–100 Hz: Pain relief (gate control theory)
•130–150 Hz: Edema reduction

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Sweep and Vector Mode
•Sweep mode: Prevents accommodation by changing frequency (e.g., 90–100 Hz sweep)
•Vector mode: Moves the current field dynamically in tissues
•Enhances coverage and comfort

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Physiological Effects
•Increases blood flow
•Reduces muscle spasm
•Promotes tissue healing
•Provides pain relief through:
•Gate Control Theory
•Endorphin Release
•Decreased nerve excitability

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Indications
•Musculoskeletal pain (e.g., back pain, OA, sprains)
•Post-operative pain
•Muscle spasm
•Edema management
•Neuralgia, Sciatica
•Trigger point pain etc..

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Contraindications
•Over pacemakers or implanted devices
•Pregnancy (especially abdomen/lower back)
•Cancerous lesions
•Thrombophlebitis
•Open wounds (without protection)
•Over eyes, carotid sinus, or anterior neck

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Precautions
•Check skin integrity
•Proper electrode contact
•Monitor intensity during treatment
•Avoid bony prominences for better comfort

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Advantages of IFT
•Deep tissue penetration
•Comfortable stimulation (medium frequency is better tolerated)
•Versatile use for acute and chronic pain
•Non-invasive and drug-free

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Disadvantages
•Requires careful electrode placement
•Equipment is expensive
•Some patients may not tolerate the sensation
•Not suitable for all areas (e.g., facial nerves)

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Evidence-Based Practice
Systematic Reviews:
•Moderate evidence for chronic low back pain, OA knee
•IFT combined with exercise gives better results
•Effective in reducing post-op pain in orthopedics
Clinical Guidelines:
•Not standalone — best when combined with active rehab

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Recent Research Findings
•IFT with TENS vs. IFT alone: IFT more effective in deep structures
•IFT combined with manual therapy shows faster recovery
•Smart IFT devices with programmable waveforms available

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IFT vs Other Modalities
Modality Frequency Depth Comfort Common Use
IFT Medium Deep High Pain, spasm
TENS Low Superficial Medium Pain
Russian Currents Medium Deep Low Strength
Ultrasound NA Deep Comfortable Healing

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Case Study Example
• Patient: 45-year-old female with chronic knee OA
• Treatment: IFT 90–100 Hz + quads strengthening
• Outcome: Reduced VAS score from 8 to 3 in 2 weeks
• Functional improvements noted

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Demonstration & Practical Tips (IN LAB)
•Show unit
•Electrode prep
•Intensity setting tips
•Communication with patient during session

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Key Points
•IFT = Interference + Medium Frequency + Pain Modulation
•Comfortable, deep stimulation
•Clinical application must be goal-specific
•Combine with exercise for best results

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VIVA QUESTIONS

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What is the carrier frequency used in IFT?

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Name two physiological effects of IFT.

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Why is sweep frequency important?

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What is the difference between bipolar and
quadripolar application?

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References
•Kumar, G.K. (2020). Electrotherapy: Evidence-Based Practice. Jaypee.
•Low & Reed. (2014). Electrotherapy Explained.
•Cochrane Database Reviews on IFT.
•APTA Guidelines for Electrotherapeutic Modalities.
•Peer-reviewed articles from PubMed and Google Scholar.

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Thank You