Much of the confusion arises because of the link between magnetism and electricity. Maxwell, in the 's, identified that an electric field is accompanied by a. Begin to discuss how magnetism can be used to create electrical current. help to give you an idea of the relationship between magnetism and electricity. Discuss what happens to a compass when a wire with electrical current is near. Describe the relationship between electricity and magnetism. Your browser does .
Shen et al provide some useful insight with regards the role of MLCK outside the muscle contraction effects, relating to pathology, inflammation and microvascular flow.
There certainly appears to be a strong relationship between MLCK and microvascular permeability. Whether this is relevant to therapeutic effects remains to be seen, but it is currently a strong contender. Many references have considered and described the mechanism, or hypothesised about it including the Markov and Funk papers identified previously, plus Rosen, and Volpe and Eremenko, It has also been argued that the effects of the applied energy relate solely to heat generated in the tissues - i.
There is clear and unequivocal evidence that non thermal effects are 'real' and the heat does not have to be generated in the tissues in order to achieve physiological change cellular or gross tissue level. There is an argument that the effects are 'micro-thermal' in nature - beyond the scope of what might be covered here. Whatever the final outcome non-thermal or micro-thermalthere is no significant heating of the tissue with these therapies, even when applied for prolonged periods of time.
Clinical Applications The strongest evidenced clinical application of magnetic fields appears to be related to bone healing, wound healing and facilitated repair in musculoskeletal lesions, pain management and oedema resolution.
One would certainly not want to restrict the clinical applications to these fields, just that they are the strongest evidenced to date. Colbert et al b write some useful notes with regards running clinical trials with magnetic field therapy - and even if you are not inclined to run a trial, they are useful if you, as a reader, want to evaluate the quality of a trial that is in print. The use of EMF type application as a means to stimulate bone healing was initially achieved using electrode systems directly implanted at the fracture site clearly outwith the 'therapy' type of application.
More recently last 20 years or sosystems are applied externally, using a time varying pulsed electric signals, driven through a magnetic coil placed around the limb. Essentially an electric current in the applicator drives an electromagnetic field, and this in turn brings about small electric field changes in the tissues - induced - not direct - which are responsible for the physiological and therapeutic effects.
Typically, these generating currents will be applied at what we will call low frequency, typically up to Hz, though technically, these fall into the 'extreme low frequency' or ELF band.
It is certainly a case of 'more is not necessarily better' or less is more. There are literally hundreds of cell based studies which have reviewed and demonstrated cell level effects from these therapies at these low doses. They include membrane effects like the Ca ion channel changes and cytokine mediated effects e.
Funk et al provide a reasonably succinct summary as do other reviews identified in the ref list. Funk et al identify at least 7 different cell membrane based mechanisms through which magnetic and electric fields can influence activity see figure 34 page Bassett provides a simpler, but none the less useful consideration of how pulsing EM fields influence physiological activity.
Bone Healing This is a massive topic and whole books have been written on it. Most of the work has involved the delivery of PEMF energy using dynamic fields, and it is considered Bassett that it is the electric component rather than the magnetic component that has the primary effect. Pickering et al review this field and identify as have others the complexity of dose, application method and mixed reporting of the intervention making dose estimation problematic and replication of the treatment almost impossible in some cases.
This does not deny the benefit, or at least the potential benefits of magnetic therapy. At the present time, the weight of the evidence falls in favour of PEMF applications, using a dynamic electric current to generate a varying electromagnetic field. This is sent to the tissues in which local bioelectric currents are induced, and it is these that are believed, and most strongly evidenced to positively influence bone repair.
An example of a currently running clinical trial, in humans, evaluating PEMF application fresh scaphoid fractures can be found in Hannemann et al This type of trial should provide useful clinical data on which to base future intervention. OA and Degenerative Conditions Many patients purchase home based magnetic therapy devices for their 'arthritis'.
The adverts web, newspapaer to which they respond make a variety of interesting claims, some of which are probably supportable from the evidence, others rather less so. Sutbeyaz et al evaluated the effect of PEMF based therapy on pain, movement and functional capacity for a patient group with cervical OA.
The therapy was delivered via a mat which the patient used laid on for 30 minutes a session, 2 x daily for 3 weeks.
The treatment group showed significant pain reduction whilst the placebo group did not. Similarly, there were significant changes in range of movement and functional capacity. The mat produced an EM field with a mean strength of 40mT delivered in a pulsed mode at a range of frequencies between 0. There is nothing 'wrong' with pain relief and functional improvement - it is to be welcomed.
Despite some 'popular' claims about magnetic therapy halting the progress of arthritis, or even restoring the joint condition to normal which are not evidenced claimsit remain probable that the benefits of magnetic therapy for this patient group relates to pain relief - which is the primary complaint they have anyway. Their review is primarily related to animal studies, though it does provide potentially useful information relating to therapy effects.
This is an extension update of an earlier review Ohkubo et al, which considers static magnetic fields at 0.
Relation between electricity and magnetism
In animal therapy, the effects of static magnetic fields on local circulation especially in horses is often cited as an 'effect' of treatment.
Steyn evaluated a static magnetic field on blood flow in the horse metacarpus using a magnetic wrap for 48 hours. They were not able to identify any significant difference between treated and control limb blood flow perfusion.
The wraps used were 'commercially available' and whilst the authors do not identify the power output, they do report that at 7mm from the wrap, the magnetic field was not greater than the 0. The lack of significant effect may therefore simply be a demonstration that sufficient magnetic energy needs to be delivered in order for therapy based effects to be achieved.
Wound Healing Aziz et al has provided a Cochrane review on electromagnetic therapy for treating venous leg ulcers. As ever with Cochrane reviews, there is a risk the useful trials are not included and secondly that there is commonly no 'dose' consideration.
The authors conclude almost predictably that there is no strong evidence of benefit. Without trying too hard, it is easy to see that these are not the 'same' treatments. The Kenkre study did not show a difference between treated and sham treated ulcer healing. The Cochrane paper teases these results further, but this is the essentials of it. Other studies provide equivocal evidence.
Isahov et al used static magnetic therapy as a means to influence the healing of stump wounds in diabetic amputee patients. They demonstrated no significant difference in healing times between treated and control groups, though their measurement of healing was 'different' to the normal, based on measured vs estimated repair time. The magnetic therapy was delivered for almost 48 hours on average. Jing et alMilgram et alGlinka et al are amongst a group of researchers who have evaluated mangnetic based therapy in animal healing models, some providing positive results and some not.
It would appear that magnetic based therapy has the potential to positively influence wound healing, though the difference in positive and negative outcomes may simply reflect a dose based function which has yet to be resolved. Musculoskeletal Injury, Soft Tissue Injury and Repair Numerous and varied trials have been conducted on soft tissue type problems. Owegi et al demonstrated a positive effect on tendon problems tendonitis.
Lee et al also evaluated the effects of PEMF based therapy on Achilles tendinitis Both Reeser et al and Mikesky and Hayden failed to demonstrate a beneficial effect for magnetic therapy on DOMS pain - but having looked at all the evidence on DOMS pain, almost nothing makes any real difference to it. There is a lot of anecdotal evidence with regards the efficacy of magnetic based therapies for soft tissue injury, but a dearth of clinical trials in real patients which are a meaningful and b demonstrate positive outcomes.
It may transpire that magnetic based therapiees are effective in this clinical domain, but the evidence is not there yet. Pain Relief Eccles provides a useful critical review for the use of static magnets in trials, looking at pain relief issues. He identified 21 studies for inclusion in the review. The pain types reported in the positive studies included in the Eccles review covered OA mainly kneedysmenorrhoea and menstrual pain, diabetic polyneuropathy foot painRA joint pain, fibromyalgia, chronic back pain, trigger points, pain post surgery, post polio pain.
In terms of dose, the trends appear thus: The magnet power in the positive studies varied from almost G 0. Power of at least G 0. They consider both changes in nociception and analgesia not the same thing. They consider therapy effects together with environmental exposure to EM fields in an insightful review. Hazelwood and Markov review the use of EMF based therapy for trigger points and various other pain related conditions. They consider the options of treating pain locally and using the therapy at trigger points in order to achieve a 'distant' effect.
They also consider in a review style treatment for chronic back pain and soft tissue injury. Trigger points Vallbona et al used a static magnetic field at between and G in a single 45 minute treatment of trigger points for a group of post polio pain sufferers.
The real therapy generated significant reduction in pain over 4 points on a 10 point VAS scale - which is highly clinically significant. The placebo group demonstrated an average reduction of just over 1 point.
Their device delivered a pulsed shortwave The device was battery powered and incorporated into a dressing system. Treatment was for 30 minutes every 4 hours automatic for days30 minutes every 8 hours for the next 3 days then 30 minutes every 12 hours thereafter till 8 days.
The device employed was a SofPulse as per the Heden and Pilla study. Strauch et al review the use of PEMF based therapy in various plastic surgery issues including pain, post op oedema, wound healing and enhanced repair.
The demonstrated significant pain relief in the treated group compared with the placebo group. The device was small, worn on a wrist strap and delivered both static and varying 20Hz magnetic fields. The static field was measured at 0. Therapy was delivered for 2 hours each, twice daily for 2 months.
Various nerve conduction tests were included, though no significant changes were identified between treatment and sham groups. Deveraux et al compared real with placebo PEMF for tennis elbow patients, treating for at least 8 weeks. Patients used the device for at least 8 hours a day overnight.
It was small and portable. The electrical power of the device is identified, but not its applied field strength, thus it is difficult to identify the strength of the PEMF therapy received by the patient.
The results show better improvement in the treatment group compared with the placebo group, though they did not generally reach statistical significance. Therapy was delivered 3 times weekly for three weeks. The treatment group demonstrated significant pain relief compared with the placebo group and functional improvements were also significant for the treatment group.
The treatment was clinic based no a small portable device - more like a classic pulsed shortwave in terms of size. It delivered pulses at 5 and 10Hz for 15 minutes at between 1.
Lo et al report the outcome of a pilot clinical study using magnetic therapy for patients with lumbosacral spondylosis. Treatment was compared with a placebo intervention. This was 'different' in that the treatment was only delivered once.
The machine Medtronic R30 delivers 2T per pulse with trains of 5 pulses delivered at 10Hz. This is not a 'gentle' therapy - the power was adjusted such that visible muscle twitching was minimised!
Clinical Application Summary There is a wide mix of research papers covering clinical applications and potential benefits. It may transpire that this therapy is useful for local vascular and microcirculatory effects and for soft tissue problems after injury but the supportive published evidence is not yet available.
References Al Mandil, M. Electromagnetic therapy for treating venous leg ulcers. Cochrane Database Syst Rev 3: Electricity is a form of energy that is transmitted through the wires especially copper wires for operating the various machines and devices such as lights, fans, refrigerator, computers, television, air conditioner, washing machines, etc.
Electricity is the property of charged particles such as electrons and protons. When these particles are at rest, it is called static electricity. Static electricity occurs due to the existence of charged particles. On the other hand, when charged particles flow through the conductor, it is called current electricity. Because, when the charged particles flow through the conductor, electricity also flows.
We know that current means the flow of anything in a particular direction. For example, the flow of water in a particular direction is called water current. In the similar way, the flow of electricity or charged particles especially free electrons in a particular direction is called current electricity or electric current.
Magnetism is a type of attractive or repulsive force that acts up to certain distance. The distance up to which this attractive or repulsive force acts is called magnetic field. Magnetism is caused by the moving electric charges especially electrons. When two magnetic materials are placed close to each other, they experience an attractive or repulsive force.
We know that all the objects in the universe are made of small particles called atoms. The atoms consist of sub atomic particles such as electrons, protons, and neutrons. The strong nuclear force between the protons and neutrons makes them stick together to form nucleus.