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Faradic Stimulation

Original Editor - Abdallah Ahmed Mohamed

Top Contributors - Abdallah Ahmed Mohamed, Misha Ahir, Rachael Lowe, Kim Jackson, Aminat Abolade, Rishika Babburu and Ewa Jaraczewska  

Introduction

Faradic current is a short duration interrupted direct current with a pulse duration ranging from 0.1 to 1 ms with a frequency of 50 to 100 Hz. Faradic current is surged to produce tetanic contraction and relaxation of the muscle. Treatment with faradic current also known as Faradic Electrical Stimulation(FES) or faradism.[1]

Historical Context

Faradic stimulation represents one of the earliest forms of electrical stimulation used in physiotherapy, with its origins dating back to the 19th century when Michael Faraday's discoveries in electromagnetic induction were first applied to medical treatment.[2] Named after Faraday, this modality was widely used throughout the early to mid-20th century for muscle stimulation and re-education.[3]

In contemporary physiotherapy practice, traditional faradic stimulation has been largely superseded by more sophisticated and evidence-based forms of electrical stimulation.[4] Modern neuromuscular electrical stimulation (NMES) and functional electrical stimulation (FES) devices offer greater precision in parameter control, improved patient comfort, and stronger evidence for clinical efficacy.[5][6] These contemporary modalities provide programmable waveforms, adjustable parameters, and treatment protocols based on extensive research into optimal stimulation characteristics for specific therapeutic goals.[7]

While faradic stimulation played an important role in the historical development of electrotherapy, current clinical practice favours electrical stimulation techniques with robust evidence bases, standardised protocols, and demonstrable clinical outcomes.[8] Understanding faradic stimulation remains valuable from a historical perspective and for comprehending the evolution of electrophysical agents in rehabilitation. However, clinicians should be aware that modern alternatives typically offer superior treatment options for the clinical indications previously addressed with faradic current.[9]

This historical context is important when reviewing the information presented on this page, which describes traditional faradic stimulation techniques and applications that may not reflect current best practice in physiotherapy.

Bioelectrical Principles

Faradic is an interrupted direct current that has a frequency of 50:100Hz with a pulse duration from 0.1-1ms. This frequency and duration cause contraction and relaxation in innervated (nerves intact) muscles. It does not work on denervated muscles; to cause the same effect a short pulse duration would be required. When applying faradic stimulation, the stimulation of the sensory nerve can result in the patient experiencing a pricking sensation due to the short duration of the pulse. The stimulated nerve causes a reaction in the motor fibres which makes the muscle contract.

Faradic Vs Galvanic Currents

Understanding the distinction between faradic and galvanic currents is essential for historical context, as these were the two primary forms of therapeutic electrical stimulation used in early physiotherapy practice. While both modalities utilise direct current, they differ significantly in their parameters and physiological effects. The comparison below illustrates why different clinical applications required different forms of electrical stimulation, and helps explain why faradic current was limited to treating innervated muscles whilst galvanic current could stimulate denervated tissue. This distinction was crucial in the era before modern electronically-controlled stimulators, when clinicians needed to select between these two basic current types based on the patient's neuromuscular status. Both faradic and galvanic currents are direct currents. The key differences include:

Feature Faradic Current Galvanic Current
Pulse Duration Short Long
Frequency High Low
Muscle Stimulation Innervated muscles Innervated and denervated muscles
Skin Treatment Not typically used Desincrustation, iontophoresis
Sensation Buzzing/tingling Smooth, continuous

When applying galvanic, the denervated muscle responds to this stimulus because of the long pulse duration. The denervated muscle does not respond to faradic because pulse duration is short.

Types of galvanic waveform

  • Rectangular surging: the current turn on and off intensity abruptly.
  • Trapezoidal surging: it slow rise and slow fall.
  • Triangular surging: it raises slowly, plateau’s and then falls slowly.
  • Saw Tooth surging: the gradual rise of current and abruptly falls.[10]

Physiological Effects

The physiological effects of faradic and galvanic currents are similar in some respects, though faradic current is effective only for innervated muscle whilst galvanic current can stimulate denervated muscle.[11] The reported physiological effects include:*Circulatory changes: Both currents can increase blood flow to the treated area through muscle pumping action, resulting in mild erythema due to vasodilation.[12] The rhythmic muscle contractions produced by electrical stimulation create a pumping effect that enhances venous and lymphatic return.[13] However, evidence for increased metabolism and waste product removal through electrical stimulation alone remains limited and these effects are likely secondary to the improved circulation.[14]*Muscle contraction: Electrically stimulated contractions differ from voluntary contractions in their recruitment pattern. Electrical stimulation preferentially recruits large-diameter motor neurons and fast-twitch muscle fibres, whereas voluntary contractions follow the size principle, recruiting smaller motor units first.[15] To prevent fatigue during faradic stimulation, the current is typically surged to allow periods of muscle relaxation between contractions.[16]

  • Muscle re-education: Electrical stimulation may assist in muscle re-education by providing sensory feedback and facilitating motor relearning, though evidence for this application is primarily historical and modern approaches emphasise active participation in motor learning.[17]
  • Prevention of muscle atrophy: While electrical stimulation can help maintain muscle mass in certain conditions, its effectiveness in preventing atrophy is limited compared to voluntary exercise. Evidence suggests modest benefits in specific populations such as critically ill patients or following orthopaedic surgery.[18]

Indications

The following indications represent historical uses of faradic stimulation. As mentioned above, modern physiotherapy practice employs evidence-based alternatives such as neuromuscular electrical stimulation (NMES), functional electrical stimulation (FES), and active exercise programmes for these clinical presentations.[19]

  • Facilitation of muscle contraction when inhibited by pain
  • Muscle re-education: muscle contraction is needed to restore the sense of movement. In cases of flat foot or muscle transplantation, the brain appreciates movement not muscle actions so current should be applied to restore normal movement
  • Training of new muscle action
  • Improved venous and lymphatic drainage in conditions such as oedema and gravitational ulcers through the pumping action of muscle contraction and relaxation
  • Prevention and loosening of adhesions
  • Painful knee syndrome

For current evidence-based management of these conditions, clinicians should consult contemporary clinical guidelines and systematic reviews relevant to each specific indication.[20]

Contraindications

  • Certain dermatological conditions such as psoriasis, tinea and eczema
  • Infection
  • Inflammation
  • Thrombosis or thrombophlebitis
  • Loss of sensation
  • Cancer or malignancy in the treatment area
  • Cardiac pacemakers or other implanted electronic devices
  • Pregnancy (particularly over the trunk or pelvis)[21]
  • Epilepsy (particularly for treatments near the head or neck)[22]
  • Areas of impaired circulation or compromised blood supply[23]
  • Over the carotid sinus or anterior neck
  • Directly over the eyes or reproductive organs

==Application==#The patient is positioned so that the part to be treated is comfortably supported with the muscles to be stimulated in a shortened position, although this may be modified with movement produced (e.g., slight knee flexion allowing quadriceps stimulation to cause extension)

  1. The skin surface must be examined for any cuts or abrasions; the treatment area should be cleaned with warm water to lower skin resistance
  2. The size of the active electrode should be chosen considering the size of the treatment area
  3. The electrode should be smaller than the pad to prevent the edge of the electrode being bent down on the skin
  4. The pads should be soaked in warm tap water, saline or sodium bicarbonate solution before being applied to the skin
  5. Fixation is achieved with a rubber strap or by body weight
  6. Explain the sensation to the patient
  7. When the muscle has to be stimulated, the active electrode is placed over the motor point and small current is applied. The current may need to be increased and then decreased as the motor point is found and good contraction obtained with less current
  8. When a muscle group has to be stimulated, the active electrode is placed at the end of the muscle group so that the current spreads through the whole group

References

  1. ↑ Purva Nanivadekar and Shivali Kar, “Microcontroller based Rehabilitation Stimulator”, International Journal of Computer Applications 2013
  2. ↑ Payne E. A Short History of Electrotherapy. In: Kitchen S, editor. Electrotherapy: Evidence-Based Practice. 11th ed. Edinburgh: Churchill Livingstone; 2002. p. 3-15.
  3. ↑ Robertson V, Ward A, Low J, Reed A. Electrotherapy Explained: Principles and Practice. 4th ed. Edinburgh: Butterworth-Heinemann; 2006. p. 1-28.
  4. ↑ Watson T. Electrotherapy: evidence-based practice. 12th ed. Edinburgh: Churchill Livingstone; 2008. Available from: https://www.electrotherapy.org/
  5. ↑ Maffiuletti NA, Minetto MA, Farina D, Bottinelli R. Electrical stimulation for neuromuscular testing and training: state-of-the art and unresolved issues. Eur J Appl Physiol. 2011;111(10):2391-2397. Available from: https://pubmed.ncbi.nlm.nih.gov/21866361/
  6. ↑ Doucet BM, Lam A, Griffin L. Neuromuscular electrical stimulation for skeletal muscle function. Yale J Biol Med. 2012;85(2):201-215. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3375668/
  7. ↑ Bax L, Staes F, Verhagen A. Does neuromuscular electrical stimulation strengthen the quadriceps femoris? A systematic review of randomised controlled trials. Sports Med. 2005;35(3):191-212. Available from: https://pubmed.ncbi.nlm.nih.gov/15730336/
  8. ↑ Chartered Society of Physiotherapy. Guidance for the Clinical Use of Electrophysical Agents. London: CSP; 2016. Available from: https://www.csp.org.uk/publications/electrotherapy
  9. ↑ Cameron MH. Physical Agents in Rehabilitation: An Evidence-Based Approach to Practice. 6th ed. St. Louis: Elsevier; 2022. p. 221-268.
  10. ↑ Mangala B. Satardekar and Deepak V. Bhoir “ANALYSIS AND ENHANCEMENT IN THE PERFORMANCE OF ELECTRICAL MUSCLE STIMULATOR.”
  11. ↑ Robertson V, Ward A, Low J, Reed A. Electrotherapy Explained: Principles and Practice. 4th ed. Edinburgh: Butterworth-Heinemann; 2006. p. 179-182.
  12. ↑ Kitchen S, Bazin S, editors. Clayton's Electrotherapy. 11th ed. London: WB Saunders; 2002. p. 234-237.
  13. ↑ Broderick BJ, Breathnach O, Condon F, Masterson E, Olaighin G. Haemodynamic performance of neuromuscular electrical stimulation (NMES) during recovery from total hip arthroplasty. J Orthop Surg Res. 2013;8:3. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3598528/
  14. ↑ Miller BF, Gruben KG, Morgan BJ. Circulatory responses to voluntary and electrically induced muscle contractions in humans. Phys Ther. 2000;80(1):53-60. Available from: https://pubmed.ncbi.nlm.nih.gov/10623960/
  15. ↑ Gregory CM, Bickel CS. Recruitment patterns in human skeletal muscle during electrical stimulation. Phys Ther. 2005;85(4):358-364. Available from: https://pubmed.ncbi.nlm.nih.gov/15794706/
  16. ↑ Binder-Macleod SA, Snyder-Mackler L. Muscle fatigue: clinical implications for fatigue assessment and neuromuscular electrical stimulation. Phys Ther. 1993;73(12):902-910. Available from: https://pubmed.ncbi.nlm.nih.gov/8248298/
  17. ↑ Rushton DN. Functional electrical stimulation and rehabilitation--an hypothesis. Med Eng Phys. 2003;25(1):75-78. Available from: https://pubmed.ncbi.nlm.nih.gov/12485788/
  18. ↑ Maddocks M, Gao W, Higginson IJ, Wilcock A. Neuromuscular electrical stimulation for muscle weakness in adults with advanced disease. Cochrane Database Syst Rev. 2013;(1):CD009419. Available from: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD009419.pub2/full
  19. ↑ Watson T. Electrotherapy: Evidence-Based Practice. 12th ed. Edinburgh: Churchill Livingstone; 2008. Available from: https://www.electrotherapy.org/
  20. ↑ Chartered Society of Physiotherapy. Guidance for the Clinical Use of Electrophysical Agents. London: CSP; 2016. Available from: https://www.csp.org.uk/publications/electrotherapy
  21. ↑ Chartered Society of Physiotherapy. Guidance for the Clinical Use of Electrophysical Agents. London: CSP; 2016. Available from: https://www.csp.org.uk/publications/electrotherapy
  22. ↑ Robertson V, Ward A, Low J, Reed A. Electrotherapy Explained: Principles and Practice. 4th ed. Edinburgh: Butterworth-Heinemann; 2006. p. 131-133.
  23. ↑ Cameron MH. Physical Agents in Rehabilitation: An Evidence-Based Approach to Practice. 6th ed. St. Louis: Elsevier; 2022. p. 251-253.
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