REVIEW ARTICLE
Year : 2023 | Volume
: 23 | Issue : 1 | Page : 10--16
A review of interferential therapy application in sport physical therapy
Ahmad Khiyami1, Raed Saleh Almalki1, Nadeen Khayame2,
1 Department of Physical Therapy, King Abdulaziz Hospital, Makkah, Saudi Arabia
2 Department of Public Health, Healthcare Cluster, Makkah, Saudi Arabia
Correspondence Address:
Ahmad Khiyami
Department of Physical Therapy, King Abdulaziz Hospital, Makkah
Saudi Arabia
Abstract
Interferential therapy (IFT) is considered to be the most commonly used electrical modality in the management of different cases in the physiotherapy clinic. IFT use of therapeutic frequencies involves the combination of two-medium level frequencies that penetrate deeply through the skin and muscle to the acupuncture point, without causing pain to the patients. In addition, it has many advantages as it is considered safe, easy to use, nonpharmacological, noninvasive, and effective in terms of rehabilitation. It is also effective in most musculoskeletal disorders as well as in sports injuries such as muscle, joint, ligament, tendon, and bone injuries. IFT has five main approaches relating to its effect on pain, muscle stimulation, vasodilatation, edemas, and bone healing. All of these approaches require different frequencies, intensities, and patterns in order to achieve the anticipated outcome. In conclusion, IFT is effective and easy to apply, and many researchers recommend that it should be considered an option in terms of rehabilitation and sports management.
How to cite this article:
Khiyami A, Almalki RS, Khayame N. A review of interferential therapy application in sport physical therapy.Saudi J Sports Med 2023;23:10-16
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How to cite this URL:
Khiyami A, Almalki RS, Khayame N. A review of interferential therapy application in sport physical therapy. Saudi J Sports Med [serial online] 2023 [cited 2023 Sep 29 ];23:10-16
Available from: https://www.sjosm.org/text.asp?2023/23/1/10/383098 |
Full Text
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Introduction and Theory of Interferential Therapy
Interferential therapy (IFT) or interferential current (IFC) is a form of transcutaneous electrical stimulation that uses medium-frequency electrical current. It is a commonly used physical therapy treatment modality used for different forms of therapeutic management and rehabilitation. IFT is a safe therapeutic option for the management of different musculoskeletal disorders. In addition, it has few side effects as a result of being a nonpharmacological and noninvasive form of treatment.[1],[2],[3],[4],[5],[6] Many portable IFT operators have become readily available recently with many magnitudes. These are good for delivering the correct therapeutic IFT current, though some devices have inadequate implementation and ability.[7]
As far as therapeutic effects are concerned, on the one hand, the electrical current has to penetrate deeply through the musculature and skin.[8] The resistance caused by the musculature and skin could be painful for the patient and could reduce the current flow which reduces the anticipated effect.[7],[9] Consequently, a higher frequency current might be required to achieve the predicted outcomes.[7],[9],[10] On the other hand, low-frequency currents result in high skin resistance. In contrast, high-frequency currents result in low skin resistance and pass through the musculature and skin without pain.[10]
However, high- and low-interferential frequency currents are not suitable with regard to stimulating nerves. For that reason, in the 1950s, an Austrian physicist called Nemec developed the IFC by crossing and combining two different medium-frequency waves (4000 and 4100 Hz) to produce a new therapeutic-frequency current known as amplitude modulation effects of 0–250 Hz. These produce lower skin resistance and allow deeper penetration into the skin and muscles.[8],[11],[12],[13] This new combined current is supposed to be produced at the site of the bisection of the two diagonally opposed currents as a result of their interference with each other.[3],[14]
The uses of IFT include enhancing muscle strength and endurance by continuing contraction through the muscles, controlling and reducing pain by pain gate theory and pain mechanism,[15],[16] as well as enhancing tissue healing, managing spasticity, reducing joint swelling, improving the range of motion of joints, and assisting in the use of orthoses.[16],[17],[18],[19],[20],[21] IFT has many advantages including being completely noninvasive, easy to use, cost-effective, and suitable for wide use as it can be self-administered at home.[22] Notable that the main cons of therapeutic interferential are to be considered the placebo effect in many studies in terms of pain which may give false and inaccurate indications.[23],[24]
Interferential Application
There are many IFT application methods, including bipolar (one channel/two electrodes), quad polar (two channels/four electrodes), and the stereodynamic method (three-dimensional).[7],[9] Studies have shown that the bipolar technique may be clinically more effective than the traditional true IFC arrangement (quad polar) in terms of torque production, depth effectiveness, and comfort on the part of the patient,[10] while quad polar is more effective in terms of pain.[7] Moreover, there are five types of frequency sweep: first, constant frequency (1–100 Hz) which produces an analgesic effect conducting with sensory nerve ending to relieve pain, and fine vibrations of ions without a heating effect. Second, rhythmic frequency (1–100 Hz) can produce relaxation in the tissue with hyperemia and increase circulation activity caused by stimulating fine vibrations in the ions that are commonly needed to facilitate the healing process and relieve edema. Third, constant frequency (1–10 Hz) causes muscle contractions as a result of motor nerve facilitating. Fourth, rhythmic frequency (1–10 Hz), which stimulates the motor nerve and causes a vasodilatory effect that facilitates the absorption of exudates. Fifth, rhythmic frequency (90–100 Hz) causes analgesic and vasodilatory effects on tissue and it is commonly used for neuralgic types of pain.[7] The frequency sweep pattern includes triangular, rectangular, and trapezoidal. It is worth noting that the frequency pattern makes a significant difference to the stimulation received by the patient.[7],[9]
IFT has three types of electrodes: (1) plate electrodes which are made of rubber in order to be more comfortable for the patient. A therapist can achieve a deeper penetration by using a large electrode and a superficial one by using a small electrode. (2) Vacuum electrodes which consist of a rubber suction cup. The aim of using vacuum electrodes type is to provide good contact to flat, smooth areas such as the back and plump knees. (3) Combined electrodes which can be applied at the same time in different areas of the body and contain different sizes such as small, medium, and large.[9],[25],[26]
Interferential Parameter and Frequency of Treatment
It had been recommended that IFT should be applied three times per week for 12 weeks (depending on the severity and phase of the injuries) in order to achieve the desired outcome. The intensity of the current should be firm but comfortable to the patients, leading to the tingling sensation, without or with a contraction of the muscles. The duration should be 10–15 min, but no longer than 20 min in the same area. In the event of many areas needing treatment, the overall application should not exceed 30 min.[17],[26],[27],[28],[29]
Interferential Clinical Application in Sports Management
Studies have shown that there are five main IFT approaches that can be used in sports management. These relate to the effect on pain, muscle stimulation, vasodilatation, edemas, and tissue healing. All of these require different frequencies and intensities in order to achieve the desired outcome. These approaches should be considered carefully as part of the management process.[7],[9]
Effect on pain (pain gait theory)
Many studies have shown that IFT should be considered principally for use in the control of pain which markedly reduces the pain.[9],[30] IFT is commonly used clinically in terms of reducing pain in the form of an analgesic effect.[18],[31],[32],[33],[34],[35] The sedative effect of therapeutic IFT involves increasing local vasodilatory on the tissues and the pain gait theory[15] which can be explained as the following. When action potential traveling through large diameter myelinated afferent nerves to the central ascending sensory tracts in the dorsal horn of the spinal cord with small diameter unmyelinated sensory fibers carrying pain information. At a constant frequency of 100 Hz, large-diameter myelinated fibers are stimulated optimally leading to closing the pain gate and reducing the pain markedly.
It has been clinically shown that pain will be reduced at IFT frequencies (90–130 Hz), particularly when applied to acupuncture points. Pain will also diminish as a result of surges in terms of the circulation of body fluid which encourages the efflux of pain-inducing chemicals from the site of any damage.[9],[17],[26],[36],[37],[38],[39]
Furthermore, pain can be diminished by blocking C fiber transmission at >50 Hz.[7] It should be considered that IFT is not effective in posttraumatic phase (acute phase) but highly effective in the chronic phase with or without swelling. One experiment had done on male Wistar rats, approved that IFT can be effective in acute inflammatory pain and acute edema reduction but on the human still questionable.[5],[40]
Muscle stimulation effect
Nerve stimulation can be achieved at a low frequency (1–10 Hz). Such a frequency will lead to a sequence of twitches, while 50 Hz leads to a tetanic contraction. Notably, there is inadequate significant evidence regarding the strengthening effect of the therapeutic interferential unit.[9],[13] However, many researchers have illustrated that such a strengthening may be possible at an 80 Hz frequency.[41],[42] IFT is beneficial when it comes to generating useful voluntary contractions and activating the muscles after injury but may not be effective when it comes to strengthening exercises.[43] Bellew et al.[21] studied the stimulation effects of IFT in terms of the capacity to produce significant muscle contraction. The results showed that IFT could be considered a treatment choice.
The selection of the treatment parameters depends on the anticipated effects. The actual stimulation range of the motor nerve when using IFT appears to be between 10 and 20 Hz or 10 and 25 Hz. Stimulation lower than 10 Hz results in a sequence of twitches which can be clinically beneficial. However, the use of IFT has yet to be unambiguously demonstrated. Stimulation at higher frequencies such as 20 or 25 Hz can generate a robust tetanic contraction, which can be helpful to identify which muscle requires straightening.[9],[27],[44] Many studies have shown that IFT can generate muscle torque and activation and reduce muscle fatigue.[39],[45] Many researchers recommend that an exercise regime should be associated with IFT in order to produce clinical levels of muscle contraction in the muscle under treatment. It is possible to continuously stimulate the muscle beyond the fatigue point because the motor nerve forces contractions. In addition, short stimulation periods with adequate rest can be beneficial. Many IFT operators are capable of producing a surged stimulation mode which can be beneficial in reducing fatigue markedly.[7],[9],[13]
Increased local blood flow
Many experiments had shown that therapeutic interferential can increase blood flow in the targeting area, especially on the superficial parts such as skin and fascia.[7],[8],[46] Deep effect of IFT on blood flow is still questionable. Noble et al.[28] illustrated that the vascular changes at 10–20 Hz showed a significant increase in vascular blood flow. The mechanism of increasing blood flow is due to continuous contraction in the muscle as the effect of therapeutic interferential at 10–20 Hz, which increases the metabolic enzymes. Some evidence showed that the mechanism occurs due to an inhibitor or sympathetic activity, but it is still a theoretical possibility. However, based on the currently existing evidence, the most likely possible explanation for increasing local blood is continuous contraction in the muscle which increases the metabolic enzymes (10–20 or 10–25 Hz frequency sweep).[7]
Edema and tissue healing process
IFT could be used to reduce edemas and joint effusion as a result of muscle contraction and could increase the metabolic changes which encourage the reabsorption of tissue fluid as a result of vasodilatation and rising cell membrane permeability which helps ions movement to and from cells.[40],[47] The most useful frequencies that are used in edema reduction are 1–30 Hz causing electroporation and 1–10 Hz causing vasodilation effect.[7] Studies have shown that using a suction electrode may be beneficial in reducing edema, but the evidence remains limited.[9],[34] Jarit et al.[18] illustrated a change in edema following knee surgery among 87 patients who had different forms of knee surgery such as anterior cruciate ligament repair, meniscectomy, or chondroplasty. The subjects were allocated into three groups and given IFT for 9 weeks. The results showed a significant postoperative reduction in edema by week 4 as measured by circumferential knee tape. Other studies showed a significant reduction in edema size following IFT.[17],[48] IFT can promote and accelerate the tissue healing process including bone, nerve, tendon, and ligament repair by increasing the number of metabolic enzymes including monophosphate, acetylcholine esterase, phosphatase, and lysosomal enzymes which lead to new cell formation in the damaged area.[7],[9],[49],[50]
These five approaches can be used in the management of different sports injuries such as muscle spasm, strain, contusion, hematoma, tendinopathy, and ligamentous lesion as a result of reducing pain, increasing cell formation, reducing edema, and improving functional velocity.[32],[51],[52] Additionally, joint injuries such as arthritis pain can be managed as a result of improved joint functions and increased blood flow.[18],[33],[53],[54],[55] Furthermore, joint edema can be reduced by muscle contraction and improved edema absorption.[7],[9],[34],[41],[44],[54],[56] Moreover, IFT can be beneficial in the management of nonspecific low back pain in terms of pain level, function, and quality of life, as a result of enhancing muscle activity and reducing muscle spasms.[12],[16],[57],[58],[59],[60],[61],[62]
Nazligul et al.[63] reported that IFT could be useful in shoulder disorder management by reducing pain, improving the tissue healing process, and normalizing tissue around the joint. Furthermore, Cheing et al.[64] and Gaba et al.[65] showed that a frozen shoulder could be treated by IFT. Moreover, Taskaynatan et al.[66] illustrated that IFT is effective in cases of bicipital tendonitis by relieving pain and enhancing tendon function. Furthermore, IFT is considered to be effective in terms of musculoskeletal disorder management.[1],[9],[17],[18],[19],[57]
Moreover, it has been demonstrated that IFT can be beneficial in the management of carpal tunnel syndrome,[67] fibromyalgia,[38] accelerating pressure ulcer healing and decreasing ulcer size,[68] treating sports hernia,[56] chronic wound healing as a result of the stimulating effect.[69],[70],[71] It has been reported that IFT can be beneficial in rising mechanical pain threshold after eccentric exercise which can delay muscle soreness.[72] Jarit et al.[18] illustrated that the use of IFT may enhance rehabilitation after sports injuries which may accelerate the return to athletic activities.
Application of Interferential Therapy in Sports Injury Rehabilitation Phases
Different classifications regarding sports injury rehabilitation phases had been described in the literature. However, there is agreement that the phases of sports injury rehabilitation consist of four phases.[73] Phase 1 (acute phase) focuses on reducing pain, swelling, inflammation, and promoting tissue healing. Phase 2 consists of flexibility and restoring range of motion. Treatment may include exercises that are specific to the injured area, as well as electrotherapy modalities to facilitate healing. Phase 3 includes improving strength, agility, balance, and endurance. Phase 4 involves the resumption of sports training and performance. This phase aims to return the athlete to full function and prepare them for sport-specific activities. This phase aims to return the athlete to full function and prepare them for sport specific activities and a gradual return to competition, along with support to prevent re injury.[73],[74]
The application of IFT during these rehabilitation phases may improve and accelerate the return to sports and prevent recurrent injuries. It should be considered that IFT is not effective in the posttraumatic phase (phase 1), but it is highly effective in the chronic phase with or without swelling.[5],[40] IFT can be applied during the subacute phase (phases 2 and 3) to improve circulation and encourage healing of injured tissues as a result of an increase in metabolic enzymes.[7],[28] During the return-to-sport phase (phase 4), IFT can be utilized to help the athlete in recovering strength and flexibility in the injured area.[21],[43] It can also be used to prevent future injuries by improving circulation and promoting tissue healing.[7],[46]
Other Clinical Applications
IFT can be used in treating many other cases such as gastrointestinal dysfunction and stress incontinence.[9],[22],[42],[49],[75],[76] Moreover, a study involved 43 patients who were diagnosed with dysphagia. The results show that using IFT through the neck can enhance airway protection and nutrition in patients who have dysphagia as a result of enhancing saliva production.[77],[78] Furthermore, reducing knee arthritis pain,[16],[79],[80] improving knee functions,[32],[33],[53],[54],[55] and chronic neck pain.[81]
Contraindications and Precautions
There are several contraindications with regard to IFT that should be considered during rehabilitation by either the therapist or the patient. These include arterial disease, deep vein thrombosis, infectious conditions, pregnancy, hemorrhagic patients, malignant tumors, artificial pacemakers, open wounds, and dermatological conditions. Furthermore, many contraindications among athletes should be considered that including sensitive or irritable skin, open wound injuries, after training (due to high circulation and heart rate).[28],[55]
In addition, interferential precautions must be considered which include abnormal skin sensation, patients with abnormal circulation and cardiac diseases, patients with febrile conditions, patients who have epilepsy, and electrode placement over the chest area.[7],[9],[13] Satter[82] and ten Duis[83] reported that therapeutic interferential could lead to an electrical burn. Furthermore, Keramat and Gaughran[84] illustrated that IFT might interfere with the effect of drugs such as tramadol.
Conclusion
IFT is considered to be the most commonly used electrical modality in the management of a variety of cases in physiotherapy clinics. The use of therapeutic frequencies in IFT involves combining two medium-level frequencies that penetrate deeply through the skin and muscle to reach the acupuncture point without causing pain to the patient. In addition, IFT has many advantages as it is considered safe, nonpharmacological, noninvasive, and effective in rehabilitation. IFT has four main approaches that can be used in sports management, including pain relief, muscle stimulation, edema reduction, tissue healing promotion, and blood flow increase. All of these require different electrical frequencies and intensities in order to achieve the desired outcome. IFT is effective in treating a wide range of musculoskeletal disorders, including sports injuries such as muscle strains, spasms, and contusions. Moreover, it can be beneficial in many other disorders, such as dysphagia, gastrointestinal dysfunction, incontinence, low back pain, chronic knee osteoarthritis, and wound management, and accelerate the ulcer healing process. The precautions and contraindications with regard to IFT should be taken into consideration during rehabilitation by either the therapist or the patient.
Acknowledgments
Special thanks to the Saudi Ministry of Health for giving us all the resources that we needed and supporting us.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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